After finally picking up their dream bike and blazing through the honeymoon period with the perfect new rig, many cyclists inevitably begin tinkering.

The perfect bike they spent months researching before pulling the trigger now seems like it could be even better. One of the first places many riders go when looking for upgrades is a new wheelset. Wheels can provide an astonishingly different feel and ride experience.

Depending on construction, they can also play a huge role in efficiency and performance. There’s no shortage of metrics to consider when choosing a new wheelset, but one of the bigger questions to answer is whether a new wheel will be hookless, or a traditional “hooked” wheel.

Both have their benefits and drawbacks, but even as hookless wheels have exploded in popularity in recent years, many folks may be unaware of exactly what they are, or what they can bring to the table.

What are hookless wheels?

In the old days of the early to mid-2010s, wheelset designs, including the expanding tubeless compatible options erupting onto the market, featured an edge of the rim that curved into a sort of hook.

The hook allows a tire’s bead to snap and lock into place with added security as it is essentially being gripped by the hook. The hooked design also helped inner tubes mold into the correct position to interface with the rim and tire.

However, as carbon and tubeless wheels grew ever more popular, manufacturers began to ditch the traditional hook in favor of a flat, or straight-wall design that we now refer to as hookless. You may also hear hookless referred to as TSS, or Tubeless Straight Side. Designers build these wheels specifically for modern tubeless setups, making them ideal platforms to run at much lower pressures.

How do hookless rims work?

Instead of a hooked bead, tires fitted to hookless rims rely on pressure to lock into place.

Hunt Bike Wheels was among the first pioneers to begin bringing hookless technology to bike tires in 2016.

According to Hunt, the key factors for a tire to fit a hookless rim properly include ensuring that the rim is of the right diameter at the bead seat (the flat section that the tire sits on), that the bead seat is wide enough that the tire can sit square, and that the bead is not folded over and can work optimally. 

“When the tire is inflated and in service [on a hooked rim], it is not sitting on the bead seat but pressed into the side wall a few millimeters up the hook, and it is the bead core on the tire that is providing the reactive force to keep the tire in place,” Hunt said. “When using tubeless for this reason it is important that your tubeless tape does go up the hook a few mm just to make a good seal.”

These types of wheels have been the norm in cars and motorcycles for a long time. But with the higher pressures historically associated with road riding and to some extent, gravel riding, cycling was initially hesitant to jump on the train. That, however, has been changing.

What are the benefits of hookless wheels?

The hookless trend gained particular popularity in the mountain bike realm, where riders moved long ago toward lower tire pressures that are well suited to hookless systems.

But Hunt brought the hookless party to its road wheels too, offering what was then its H_LOCK Wedge technology on its 55 Carbon Wide Aero and 30/50 Carbon Aero Disc wheels from 2016 through 2018.

Hunt said its early iterations of hookless wheels produced rims that were 10 to 15 grams lighter at a lower price. That trend has continued into its modern hookless products, which it said feature stronger rim construction, lighter weight, lower manufacturing costs, and a more aerodynamic profile.

“Hookless rims [side walls] help reduce drag because they don’t pinch the tire sidewall inward, thus leading to the tire profile sitting slightly taller and creating a more seamless transition between the tire and rim,” Hunt said. “As a result, you get a slightly faster shape for the tire in most setups.”

Likewise, lower pressures associated with hookless wheels allow for better grip, and since there are no inner tubes and a more natural tire surface, flats should happen less frequently.

What are the drawbacks to hookless wheels?

While hookless wheels come with the benefits of aerodynamics and strength, they are not without their drawbacks.

Since pressure keeps a tire seated in position on a hookless rim, the interface between the tire and rim has to be precise in order to function properly. Even a tenth of a millimeter can cause problems, so not all tires can fit any hookless wheel. That turned a lot of cyclists off in the early days of hookless technology, as some would not be able to run the tire they wanted on a particular rim. However, as time has gone on, the range of tires suitable for hookless wheels has grown considerably.

“With the ETRTO [European Tire & Rim Technical Organization] having standardized the internal rim contour for hookless rims for the last few years, it has allowed the tire manufacturers to bring a range of tires out that match this internal shape,” Hunt said. “With ‘standardized’ rims, riders have more choice, easier fitment, and better performance out of the combination.”

Most brands include lists of tires that they’ve tested and confirmed perform as intended on their wheels.

But still, hookless tires have some limits to which tires will work, and whether they can accommodate a tube in a pinch or not.

Current standards for hookless wheels also require considerably lower pressures. Hookless wheels shouldn’t reach above 72.5 PSI, according to Hunt, so anyone who favors a higher PSI may want a rim that can accommodate higher pressures.

That may not seem like an issue for mountain bikers or gravel cyclists, whose PSIs usually sit well below 70, but road cyclists whose pressures often reach well above 70 and above may prefer something that can firm up more.

Which to choose

Almost every major wheel manufacturer makes both hooked and hookless options, and both can be stellar. Making the right choice comes down to each rider’s particular discipline, style, and needs.

Riders who enjoy the benefits of lower pressures, slight aerodynamic advantages, and who aren’t extremely particular about tire choice would probably be more than happy on a hookless wheel. Those who absolutely have to have a particular tire, who prefer to run their tires at high PSIs, or who often find themselves using tubes, may prefer a hooked option.

This post is sponsored by Hunt Bike Wheels. Learn more about Hunts hookless wheels at us.huntbikewheels.com.

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Every rider comes to a point in their trail, enduro, or downhill journey when they begin to seriously consider protecting their face, rather than just the top, back, and sides of their head.

Sometimes it takes getting whipped in the face by a stick or rock, or kissing the ground on a drop or jump for a rider to wish they had a chin bar to keep their money-maker out of trouble.

Many brands have gone to market with helmets that cater to these folks. And nearly anyone who has ever been in the market for a full-face helmet has had to decide between models that convert to a half-shell design, or traditional helmets that don’t.

Each has its benefits and drawbacks. Deciding which one is right for you usually comes down to a rider’s ability, style, and personal preferences.

So, how does one decide?

The folks at MET have been in the business of helmets for more than 30 years. They have a helmet for everyone ranging from fast XC types, to downhill thrill seekers. Two of their helmets, the convertible MET Parachute MCR, and the Bluegrass Vanguard Core, perfectly illustrate each helmet’s intended use, and for whom they are designed.

Why choose a convertible full-face helmet?

Unless you’re a world tour rider, you probably don’t spend most of your time doing the same type of riding. Mountain bikers frequently engage in widely varying types of riding, including cross country, enduro, downhill, and even commuting, often on the same bike.

Each of these ride styles generally calls for a different type of helmet for maximum comfort and protection. However, helmets can be pricey, so a lot of people opt for versatile options that can do it all.

This is where modular or convertible helmets like the MET Parachute MCR shine.

Since it is convertible, the Parachute MCR, which stands for Magnetic Chin Bar Release, functions as two helmets in one. In its full-face mode, it provides extra protection for the face when riders expect to encounter gnarlier terrain. That peace of mind goes a long way to helping riders push themselves.

That same added protection, however, can feel like overkill during more mellow rides, especially commutes. Rather than having to stick with a bulky, full-face option, modular helmets like the Parachute MCR allow riders to remove the chin bar and make the helmet into a half-shell, which makes more sense for casual rides.

The beauty of the Parachute MCR and similar helmets is that they still offer protection for riders in either mode. The Parachute MCR is ASTM-certified for the shell and Chinbar. This certification is not mandatory, but essential, as it’s the ONLY cert that tests the Chinbar, which guarantees the safety of the product for an Enduro style riding.

People who sporadically visit a bike park, but spend most of their time on tamer trails, get the benefit of a lightweight and cooler open-face design, with the option for increased full-face protection when they want it, or vice versa.

It also comes equipped with an adjustable two-position visor, which is common across most mountain bike trail or enduro helmets and gives riders more options to fight sun and trail debris.

The Parachute MCR has an MSRP of about $375.

Why choose a traditional enduro full-face helmet?

Traditional full-face helmets can be an ideal selection for those who spend most of their time racing in enduro or downhill arenas.

While convertible helmets still offer great protection, many unconvertible full-face helmets have added protection and extra features tailored to aggressive riding styles. For example, the Bluegrass Vanguard Core helmet, like the Parachute MCR, comes with an ASTM certification. But it’s also NTA certified, which means it can handle a higher impact velocity and has more impact tested coverage around the two most sensitive brain areas (the back and the temples).

If you’d like to learn more about helmet testing, we did a deep dive last year covering MET’s process.

It also cuts weight compared to the Parachute MCR and increases ventilation to keep riders cooler. So, for those who spend most of their time with a chin bar, the Bluegrass Core is beefier but lighter.

Additional features of the Bluegrass Core helmet not included in the Parachute MCR include:

• Fixed visor with safety release
• Reduced weight
• C-shaped cheek pads to maximize ventilation
• Removable mud grill

The Vanguard Core costs roughly $355.

Key similarities and important differences

Like many traditional and convertible full-face helmets, the Met Parachute MCR and Bluegrass Core have numerous similarities. These include ASTM certification, flexible visors that can absorb impact, a fit system with a 360-degree belt and micrometric and vertical adjustment, MIPS C2 technology, and in-mold construction.

The key difference in the helmets is their intended use. Enduro full-face helmets offer the best protection, DH-like coverage, ventilation, and low weight for long days of racing. They have racing-inspired features (safety release visors, mud grill, etc.) that make them ideal for the job.

Meanwhile, convertible helmets lean toward versatility. They are made to offer the protection of an enduro full face when needed, but are less concerned with being lightweight and offer less coverage than an enduro full face helmet. Their features are aimed toward adventure and are perfect for riders that enjoy a variety of terrains and crave a two-in-one option.

Helmets are the most important piece of equipment riders have, and they are not cheap. Before purchasing a full-face helmet, riders should think about the type of riding they do, then spend money accordingly.

Regardless, it’s important to choose a full face helmet that’s ASTM-certified (Chinbar and shell) to maximize your safety.

This post is sponsored by MET. Learn more about MET helmet at met-helmets.com/en/.

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The tinkerers and weight weenies that scour the internet for the latest tech to shave off a few grams or conserve a couple of watts know that there is no shortage of upgrades that can bring marginal gains to their ride.

Weight-saving upgrades come at a price, and that price increases exponentially as cyclists refine their equipment to make their bikes as fast, light, and efficient as possible. Saving just a couple of grams can cost hundreds and hundreds of dollars – have you looked at any Titanium, high-end carbon, or electronic components lately? They’re not exactly cheap.

In this economy, more riders may find themselves pinching pennies while still hoping to find an affordable upgrade that will take their riding to the next level.

According to Hayes Bicycle Components, dollar for dollar, that upgrade is brakes.

Why should you upgrade brakes?

Sure, a shiny-new electronic drivetrain will make a bike more efficient and carbon wheels will change the feel of the road or trail considerably, but new brakes can make riders feel incredibly well connected to a bike and confident to push themselves to the next level.

It’s difficult to ride confidently if you don’t trust your stopping power. Sadly, many brakes that come on new bikes, especially on the entry-level side of things, tend to be a little underpowered. Now, that doesn’t mean they don’t work, but they’re often not as responsive as some of the other options out there.

Brakes are an upgrade that all levels of riders can appreciate. While certain creature comforts and technologies may be more valued by high-level riders, reliable and powerful brakes provide real benefits to riders of all levels – from the newer untrained riders all the way up to World Cup champions. Poorly functioning brakes aren’t just a safety risk; they can also be a huge nuisance. Constant bleeding, unreliable performance, and low power are a few pitfalls that can completely ruin the riding experience for the novice and the pro alike. Better brakes can completely change the experience in the saddle.

Instead of racking up a few thousand dollars in carbon or electronic upgrades, most brake systems will only set a rider back a few hundred bucks, so if you’re looking for the best dollar-for-dollar upgrade to your ride, look no further.

What makes a good brake system?

Stopping power is the most important aspect of brakes, and there’s a lot that goes into it. Since most riders weigh between 100 – 250 pounds, there is a tremendous amount of force required to slow that momentum down.

Hayes Bicycle Components has been manufacturing high-end brake systems since the late 1990s, slowly refining its designs over more than two decades to create a product that does exactly what it is supposed to do: stop.

Hayes’ latest range of the Dominion family of brakes, including the A4, T4, T2, and A2, provides a great snapshot of the impact new brakes can have on a ride. The Dominion A4, which has long been a staple of the brand, uses a motorsports-inspired two-stroke dual-port bleed system, along with a hydraulic system that works consistently in a wide variety of temperatures and conditions. Whether you’re in the heat of the desert or the cold of the mountains, your brakes will function as expected.

The T4 and T2 models include titanium hardware and carbon-fiber levers to keep weight at a bare minimum. The A2, the newest offering in the lineup, also includes a compact two-piston caliper designed for XC and trail riders.

The Dominion line features a master cylinder that is fine-tuned to eliminate the dead space riders can feel from when they first squeeze the brake lever to when the brake pads actually clamp down on the caliper. This means riders will feel an immediate response, a powerful bite without hesitation, and modulation all through the way through the stroke.

Fit and feel

While the stopping power is the most critical element of any brake system, it’s important to remember that brakes are also a vital contact and interface point on the bike. The ergonomic qualities and handlebar position of brake levers and how a rider engages them can lead to fatigue, pain, or even injury. They also can prevent it.

For brakes with less power, riders often have to use multiple fingers, or all of them, to squeeze as hard as they can to come to a stop. This is especially true on downhill courses. The Hayes Dominion line comes with an ergonomic finger lever that doesn’t require extreme levels of force. It also comes with an optional Short Reach Lever that brings the lever closer to the bar for easy single-finger braking for riders with smaller hands. Its design also enables riders to adjust the reach of the lever with no tools for quick, no-hassle tuning even while on the trail.

Considering the amount of time folks spend interacting with their brake levers, they really need to be well-designed to ensure they remain comfortable and easy to use, even during long rides.

Style

Aside from the aforementioned performance improvements a new set of brakes can bring to a bike, they also can bring a touch of flare that can take a bike from something that looks like it came off of a shelf to a custom build. The Dominion A4 brake comes in a handful of colors including Bronze, Stealth Black / Grey, and an eye-popping limited edition Purple Hayes.

Hayes Brakes are a component that checks all of the boxes of performance, fit, and style all in one package.

The Hayes Dominion line sells for an MSRP ranging from $250 to $350, making it one of the places to look for riders aiming to get the most bang for their buck when upgrading their ride. Even after adding new rotors, a complete set could still come in well under $1,000 and completely revamp the feeling of any bike.

The post AASQ: What is the Best Bike Upgrade for the Least Amount of Money? appeared first on Bikerumor.

Over the 21 stages of the Tour de France, riders of the Pro Peloton may ride a number of different models from their frame sponsor. They will switch between the brand’s dedicated aero road bike, time-trial bike, and lightweight climbing bike, making a decision based on what that stage will bring on the day; elevation profile, wind conditions, mileage, terrain, etc., all need to be carefully considered to ensure the rider is optimally equipped. The team looks to control any factor that is controllable.

We recently received a thought-provoking question from a reader on this very topic, a question that was the inspiration for this feature. Not being aerodynamics specialists or engineers ourselves, we have recruited expertise from some of the top road frame manufacturers whose bikes can be seen throughout any Pro Peloton. Specialized, Trek, Cervélo, and Cannondale all bring some interesting and insightful discussion on the topic, ranging from the succinct and easily digestible to the results of some rather revealing virtual simulations.

The Reader’s Question

“The gradient at which it is said that weight begins to trump aero is typically around 8% for pro riders. Obviously, the slower one can ride and climb must affect this transition point in gradient. How does this gradient transition reduce as the available power output reduces for those of us who are not pros?”

The answer to that question is, it depends, as we will soon find out from our team of experts. The discussions offer some insight into bike choice in the Pro Peloton but also deliver some golden nuggets of advice as to what kind of bike we amateur cyclists would go best on.

Our contributors are:

• Marcel Keyser, an engineer with the Specialized Human Performance Team
• The Cervélo Engineering Department
• Trek Senior Aerodynamicist, John Davis
• Dr. Nathan Barry, Cannondale engineer and aerodynamicist

Dr. Nathan Barry, Cannondale Engineer, and Aerodynamicist

The simple answer is that the less power to weight a rider has, the slower they climb, and the lower the gradient of the tipping point between aerodynamic and weight savings. But that only scratches the surface of this phenomenon. To fully address this question, it’s important to go back to the fundamental science that underpins this concept to make sure there are no misconceptions. The statement of one specific gradient where weight trumps aerodynamics is an oversimplification from some arbitrary specific set of parameters.

The underlying mechanics of cycling, described by the cycling power equation, show that aerodynamics is a function of velocity, with no dependence on gradient or mass. Conversely, climbing power is a strong function of mass, gradient, and velocity. Taking the extreme edge cases; on a flat road (0% gradient) a rider expends 0 W of climbing power. At a constant speed, mass has a minimal impact on the power required, thus most of a rider’s power is spent overcoming aerodynamic drag. As the road gets steeper, the rider must expend climbing power, leaving less power to overcome drag, therefore their speed drops. So at some very steep gradients, a rider will have very low velocity such that aerodynamic resistance becomes minimal and the majority of the rider’s power is spent overcoming the gradient.

It stands to reason then, there will be some cross-over point along this gradient spectrum at which the rider expends an equal amount of power overcoming both drag and climbing power. However, this still isn’t the full picture. The question of interest isn’t about the magnitude of power, but rather differences in performance. What we are really interested in is how changes in drag or mass affect performance. A simple example might be a choice of wheels. A shallow wheelset might be lighter but sacrifices aerodynamic efficiency compared to a well-engineered deeper rim. Clearly, on a flat road the deeper, low-drag wheelset is preferable. The question becomes, how steep does the road need to be before the lightweight wheels are faster than the heavier but lower-drag wheels? Often this is referred to as the tipping point.

What becomes clear from this example is that the gradient at which the tipping point occurs will depend on the relative difference in drag and mass. A big drag savings with a small weight penalty will have a much higher tipping point than a change that has a small drag savings but large weight savings. The tipping point is also a function of velocity. Even when climbing, a rider is pushing through the air so there is always a component of aerodynamic drag. While it is reduced at lower speeds while climbing, it never drops to zero, so long as you are moving. As noted in the question statement, this is the reason why the tipping point is higher for professionals. Due to their higher power (and power to weight), they climb faster, and at a given gradient, they are traveling faster than an amateur and so have higher aerodynamic resistance to overcome. Aerodynamic savings have a larger influence on performance.

A second concept to layer on top of this is that these differences in rider performance are related to the system as a whole, not just the component, or the bike. Consider a wheelset upgrade that saves 100 g of weight — ignoring any aerodynamic differences for now. For a high-performance wheelset in the range of 1,600 g, a 100g reduction is a big saving (6.3%). For a complete bike of ~7.5 kg that would be a 1.3% weight reduction. However, cycling performance is determined by the total system mass — including the rider.

Typically, the bike is only about 10% of the total system weight. For a 75kg rider on this bike, the 100g weight savings is only a 0.1% reduction in system mass. As such, the climbing performance improvement from such a change will be proportionally small. The same is true of differences in aerodynamic drag. Changes in drag need to be considered as a function of the whole system. However, a 10% reduction in system mass is impossible when considering only the bike, this is not out of the realm of possibility when you consider a bike with no aerodynamic optimisation versus one dedicated to lowering drag.

How does rider power affect the gradient transition? There is no one answer to this; it comes down to those three key variables: change in drag, change in mass, and rider power to weight. For a given configuration (a given difference in drag and mass) you can model a curve for tipping point versus rider power to weight. This will show how your performance with a given setup compares to that of a pro who might have significantly higher power to weight. But that will only apply to that specific equipment configuration. As soon as you change the relative differences in drag and mass, the model will no longer be relevant. It is hard to simplify this since differences can vary widely. Between wheelsets, frames, cockpits, helmets, and clothing, there can be big differences in both drag and mass.

To try and provide some insight to those who don’t want to build all this into a spreadsheet, we can frame some of these principles in a less complex way using a very simple case study. Consider what happens when you add 1 kg of dead mass to your bike, i.e. with no benefit from reduced drag. In the context of high-performance road bikes, this is a big change in bike weight. Certainly, something that a rider will feel when they hold or pick up the bike. Most road riders would consider this to have a dramatic impact on performance. If we take a case study for an amateur rider: a 75kg rider, 7.5kg bike, 7% gradient climb, 15km/h road speed. Climbing at this speed and slope would require ~275 W. An amount sustainable for a fit amateur rider of this size (3.7 W/kg). The addition of the 1kg dead weight would add only 3W resistance under these conditions. This is not nothing, but it is just a little over a 1% increase in resistance. For a rider who isn’t competing at a high level, this difference is not going to make or break their ride. In fact, this equates to less than 0.5-second time loss over a 5km climb. If we reduce that performance to 2.5 W/kg the power difference is 2 W and the time difference is 0.5 seconds to the same significant figures. Basically, less power available reduces road speeds, which reduces the magnitude of power differential but increases the time saved — since the rider’s total time over the segment is proportionally longer.

Weight is not as significant as most riders probably believe. Even with no aerodynamic improvement, a 1 kg difference has a relatively small impact on road speed. Conversely, if you start with a setup that has relatively high drag, a 1kg mass difference could be spent on a huge amount of aerodynamic optimisation. For the same rider and power output you could see at least 20W power savings on a flat road when comparing a classic round tube frame with low-profile wheels to a modern race bike. So perhaps a simpler question to address this phenomenon is how much should a rider care about weight or aerodynamics? While it is much easier to feel and measure the weight of a bike, for almost all riders and scenarios, aerodynamic optimisation will have a much greater impact on your on-road speed than reducing the weight of the bike.

If we revisit the wheel comparison from earlier, we can consider one specific equipment choice and examine the calculation of the tipping point for our 75kg rider at 275 W. Take two wheelsets: the first is lightweight at 1,300 g but has a shallow rim and high drag. The second uses a deep aerodynamic rim with a weight of 1,500 g and a drag reduction of 0.010 m². This represents a realistic figure based on wind tunnel test results for a pair of wheels on a complete bike.

The power distribution as a function of gradient for this rider is plotted below. This model effectively has the rider maintaining a constant power output and redistributes that power based on the requirements at each gradient. From experience, we know that the increase in gradient is coupled with a decrease in speed. At 0% the rider is moving very quickly (~38 km/h), compared to very slowly (~11 km/h) at 10%. This plot highlights how the rider’s power distribution changes as the road becomes steeper. With increasing gradient, there is more power required to overcome the elevation gain, leaving less power available to maintain the speed seen on the flat. As speed drops, so does the aerodynamic power requirement.

For the two wheels, we can calculate these power distributions for each configuration. Comparing the two sets we can derive the tipping point to occur at a gradient of 6%. Remember that this is the inflection point. At any gradient up to 6%, the heavier, lower-drag wheelset is faster. Only once the gradient exceeds 6% is there any advantage for the lighter wheelset. Note, in the above graph, that at a gradient of 6% significantly more of the rider’s power is distributed to climbing compared to air resistance, and yet the performance of the two configurations is equal at this gradient. This comes down to the relative impact of those differences on the performance balance. As described earlier, changing rider power, drag savings, or weight savings will change the value of the tipping point.

The figure above shows the power difference based on a fixed velocity (as calculated for the first configuration with the heavier, lower drag setup). In this case, positive values indicate the additional power required by the lighter wheelset, negative values indicate where the lighter wheelset is saving power over the heavier wheelset. The horizontal intercept at 6% indicates the tipping point. Note that the magnitude of power difference between the two configurations is not equivalent. Whilst the lighter wheelset is faster above 6% the power saved is an order of magnitude smaller than the savings seen with the low drag wheelset on low gradients.

Cervélo Engineering Department

Aerodynamic impact grows non-linearly as speed increases. Pro riders produce more watts and weigh less, which results in a faster average speed — which also means the absolute aerodynamic impact is greater.

Relatively speaking, on flat ground, an amateur rider will benefit more from an aerodynamic frame than the pro rider because they produce less power and typically weigh more, and the aerodynamic reduction in drag is a greater percentage of their total power output.

Once the road goes uphill, though, weight becomes the determining factor, and speeds drop. A pro rider will still produce more power and weigh less than an amateur rider, so they will maintain a higher speed, which maintains aerodynamic performance. An amateur rider will weigh more and produce less power, so their speed will drop more quickly than a pro, also reducing the aerodynamic impact of the bike.

Assuming bike weights are the same, along with the assumptions stated above regarding power output and rider weight, the weight versus aero tipping point for the average rider is likely around a 4-5% gradient versus approximately 8% for the pro rider.

John Davis, Trek Senior Aerodynamicist

The reader’s 8% tipping point was accurate several years ago for the trade-off between typical aero and lightweight bikes at pro speeds. However, with most race bikes receiving aero treatment nowadays, that tipping point has been reduced.

Keep in mind that on a loop course, you must descend what you climb. Factoring in descending, the Emonda versus Madone tipping point for an out-and-back climb and descent changes from ~3% to ~6% for the 150W rider (this simplistic calculation neglects braking losses).

Now, almost all race bikes receive some aerodynamic treatment, which has reduced the tipping point from the ~8% level the reader asked about. This example compares our 2018 Emonda versus our 2021 Emonda, but the same trend is often seen across the industry.

Other factors that come into play:

• I assumed no wind; headwinds and most crosswinds will push the tipping point in favor of the aero bike while tailwinds will push the tipping point in favor of the climbing bike
• Increasing rider weight will push the tipping point in favor of the climbing bike and decreasing weight will push the tipping point in favor of the aero bike (roughly by 0.2% grade for every 10 kg in this example)

Marcel Keyser, Engineer With the Specialized Human Performance Team

For the simulation, we created three “virtual” bikes — weight, CdA (coefficient of aerodynamic drag), and a consistent rolling resistance — and ran them in a number of scenarios. We used our Tarmac SL7, the Aethos, and then a “pure” aero bike based on what we know from many dedicated aero road platforms from a variety of manufacturers. 

The rider has 70 kg + 1 kg of gear. Rolling resistance is similar to a nice Turbo tire.

Conclusions

A. General

1. The stronger a rider is, the steeper the road needs to be to hit the break-even between aero and weight. 
2. Stronger riders work more against aero due to higher average speeds.

B. Tarmac SL7 vs. Aethos (Lightweight)

1. Climbs need to be steeper than approximately 5% to see the advantage of the lower weight.
2. It’s interesting to see how different rider speeds play a big role in when the Aethos versus the Tarmac choice delivers an advantage.

Based on 3 W/kg, 4.5 W/kg, and 6 W/kg, representing amateur, strong amateur, and pro riders, respectively — we know it starts to matter beyond 5% grade for all riders, but the big-time gaps don’t occur until steeper slopes, so we calculated the time delta (change) over an hour of riding a 10% slope on a Tarmac versus an Aethos for each of these riders. Essentially, how much faster the Aethos covers the distance that a Tarmac SL7 does in an hour. You’ll see that, and watts saved, in the below summary graphs.

• At 3 W/kg, the Aethos is 25 seconds ahead after an hour over the Tarmac SL7 on a 10% slope. 
• At 4.5 W/kg, the Aethos is 19 seconds ahead after an hour over the Tarmac SL7 on a 10% slope.  
• At 6 W/kg the Aethos is 14 seconds ahead after an hour over the Tarmac SL7 on a 10% slope.  

It’s important to note that with today’s races, the aero advantage over an entire day and the rarity of any race with sustained 10% slopes, combined with the need to add ballast to make an Aethos UCI legal, make the Tarmac SL7 the undeniable race choice for our riders.

We did the Tarmac SL7 versus a “Classic” aero road bike for fun too. The results were pretty incredible. The Tarmac SL7 gives up almost nothing on the flats and gains 4X that time back on a climb.

C. Tarmac vs. “Classic” Aero Bike

1. There is almost no disadvantage on FLAT road.
2. The delta power plot shows approx. 1 W disadvantage on flat and 2 W advantage on climbs for the Tarmac. This sounds like 50%/100%.
3. BUT! Look at the TIME savings per hour bar graphs in the summary plots above:

• The Tarmac loses 5 seconds in 1 hour on the FLAT and wins 20-25 seconds in 1 hour on a CLIMB versus the “Classic” Aero Bike.
• This delta is huge, validating the incredible combination of lightweight and aero that the Tarmac delivers.

Thank you again to Specialized Bicycles, Trek Bikes, Cervélo, and Cannondale for contributing to this feature.

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Rear shocks come in a wide variety of shapes and sizes that manufacturers tailor to very specific needs of riders ranging from XC racers to downhill shredders.

For many, swapping out a shock is an expensive and anxiety-inducing task that involves a bit of math, and a whole lot of research to find the right rear-end trail partner.

That question is not necessarily a simple one. Local trails are littered with strong riders sporting both options. In most cases, they will all tell you their setup is superior.

In the end, the debate over air or coil shocks comes down to fit, feel and ride style.

What are the benefits of an air shock?

Air shocks are pretty much the only thing you’ll see on lower-travel mountain bikes. As a rule, they are lighter than their coil counterparts and more progressive in their travel.

That means that as the shock compresses, it takes more force to move through travel, reducing the frequency with which they bottom out.

However, because of the internal pressurized components of air shocks, there usually are more friction points that can cause minor kinks as the shock progresses through its full travel.

Additionally, oil inside air shocks tends to heat up during rides, particularly those in which the shock sees a lot of motion. Extended technical downhill sections or rock gardens create friction inside the shock that heats oil and air inside. Less viscous oil means a shock will move a bit more freely, so it may not feel as dialed as when the ride began.

Shocks like the Fox Float X and Float X2 are among many that ease this issue with a piggyback system. But shocks with piggybacks generally only go on longer-travel bikes, not on lower-travel XC rigs.

What applications or ride types are better suited to air?

Air shocks are ideal for cross-country riders and anyone who is looking to save weight. Coil shocks tend to be heavier than air shocks, so running them is pretty much a no-go for many racers. However, air shocks don’t solely cater to XC race types.

Even seasoned downhillers use air shocks. One of the biggest benefits of air shocks is their adjustability. Bikes are so versatile now that many are right at home at the downhill park and still fun to cruise flat singletrack or hike-and-bike trails.

Being able to dial in the suspension to account for that much variability in trail conditions is incredibly important in a do-it-all bike.

What are the benefits of a coil shock?

What coil shocks lack in at-home adjustability, they make up for in their smoothness and responsiveness. Most people use the word “supple” to refer to coil shocks.

Unlike the progressive nature of air shocks, coil shocks usually have a linear travel profile, meaning the same amount of force is required to move the shock through particular points deeper in the travel. That provides consistency and uniform responses to rider input.

Keep in mind, not all bikes can accommodate a coil shock. To get the best benefit from a coil shock, riders should select a bike that is designed to accept that type of suspension and compensate for the linear profile.

While not as easy to adjust, coil shocks still have some tunability. It’s just a bit more complicated to dial in.

To significantly change the pressure of a coil shock, riders usually have to buy a new coil. It’s not necessarily cheap and can involve some trial and error before finding the perfect spring.

Since coil shocks are built around an exterior spring, they do not usually see the same issues with friction and heated oil as air shocks.

What applications or ride types are better suited to Coil?

For the most part, coil springs thrive in the downhill arena. Their responsiveness helps riders feel more connected to the bike and stuck to the ground. Enduro riders, too, often run coil shocks. Since the speed of climbs doesn’t really matter, many are happy to find a shock that is smooth and supple when headed downhill, as long as it isn’t a complete slog when the trail points upward.

With the right coil shock, climbing should still feel relatively efficient. Coil shocks come with a bit of a weight penalty. But even for everyday trail riding, those who are not concerned with a little extra weight can often find a more consistent cushioned feel with a coil.

Which is more tunable for the at-home mechanic?

Air shocks easily win the at-home tuneability category, especially for bikes on the lower end of the travel spectrum. They provide more versatility that can help riders dial in feel for different trail or weather conditions and account for added weight.

With a shock pump, riders can dial in resistance based on their body weight, and quickly make changes to account for the added weight of things like large water bladders or bike-packing luggage. Air volume (not pressure) is also fairly easy to tune with the use of volume spacers. These spacers go inside the air chamber of the shock, and change the amount of mid-stroke and bottom-out resistance.

They also utilize rebound controls and lockout switches that typically include two or three stages for full-open, mid-open, and locked-out positions to make climbing or tame trail riding more efficient.

For example, the Fox Float X2 includes eight different click settings for high-speed compression, 16 for low-speed compression, eight for high-speed rebound, and 16 for low-speed rebound. That’s a lot of wiggle room.

However, Fox’s DHX and DHX2 are not without tuneability. Both come with an option two-position open/firm lever to tighten things up in climbs. The DHX offers an adjustment range of 16 clicks for low-speed rebound and 11 for low-speed compression. The DHX2 offers eight clicks for high-speed compression and 16 for low-speed compression. It also offers 16 clicks for low-speed rebound, and eight clicks for high-speed rebound with Fox’s proprietary VCC technology.

This post was sponsored by Fox Factory. 

ridefox.com

The post AASQ: What’s the Difference Between Air and Coil Rear Shocks? appeared first on Bikerumor.

We know, there’s no such thing as a stupid question. But there are some questions you might not want to ask your local shop or riding buddies. AASQ is our weekly series where we get to the bottom of your questions – serious or otherwise. Hit the link at the bottom of the post to submit your own question.

This week we are joined by hub design experts at Tairin Wheels, Onyx, TrailMech and Stan’s NoTubes, to take on a reader’s question about silent hubs. Aside from the absence of the sound of a swarm of angry wasps (which many folk are into), what are the actual benefits, if any, of a silent rear hub? Your contributors are as follows:

• Daniel Orellana, Jim Gerhardt and Shannon Hansen at Onyx Racing Products
• Jose Hsu, Design Engineer at Tairin Wheels
• Alexander Ivanov, Managing Director and Lead Designer at TrailMech
• Stan’s NoTubes – this was a collaborative effort from multiple engineers

Are there any advantages to a silent hub? Brands are going to great lengths to make quiet or completely silent hubs, but are there actually any durability advantages, or drag reduction to benefit from as a bonus?

Tairin Wheels: While there aren’t many designs of completely silent hubs out there compared to the abundance of ratcheting hub designs, a silent clutch design can be approached in many different ways. Aside from the benefits of being silent when freewheeling, one of the goals for a silent clutch design is to reduce the wear in the engaging mechanism, should it be a roller clutch, sprag, or an interference clutch with retracting elements.

The ratcheting you hear on standard hubs comes from the potential energy stored in the pawl or ratchet spring converting into kinetic mechanical energy in the form of sound waves. The first and most obvious observation is the energy loss, referred to as friction in the clutch against freewheeling; but another occurring consequence is wear at the point of contact. If the ratcheting element/geometry is the same used for engaging and torque transfer, eventually, at some point there will be significant wear to impede or lower the torque transfer rating. A slipping ratcheting mechanism most often leads to complete failure soon after.

For those that would say that they never had problems with wear on their mechanisms or ratchet rings, the effect of wear is more evident the smaller the teeth, the higher the engagement points in a revolution.

An interference mechanism with retracting elements is the approach we take in our upcoming silent hub design, where we separate the friction bearing element out of the engaging mechanism, with the benefit of silent freewheeling. Interference mechanisms, like seen in all ratcheting designs, offer the best weight to strength ratio for torque transfer. This is especially true in face gears (star ratchets), which are fantastic when the teeth are of adequate size, but can suffer from wear failures at a higher teeth count per same ring diameter (higher POE) just from freewheeling. With an initiator/retracting mechanism, the wear of the teeth is spared.

Onyx: There can be many advantages to a silent rear hub. Some of the feedback we’ve gathered over the years has aimed at silent hubs offering a more pleasant ride and connection with nature on the trail. This also allows the rider to hear all the other noises on the bike, albeit good and bad, such as tires working, suspension moving, brakes rubbing, and even cable rattle against the frame. 

The mechanical relation to a silent hub is usually the drag coefficient of the engagement system. At many times the rider is coasting/freewheeling and many high engagement hub systems have a large amount of drag in this motion from the pawl/ratchet assemblies moving over their engagement teeth. On the Onyx Design, the Sprag clutch glides on a smooth surface which provides minimal drag and gives the byproduct of silence. A lack of drag helps riders sustain speed and efficiency when freewheeling. Durability would not be related to the noise in our hub, but it may be on other designs.

TrailMech: One must be clear about what the term “advantage” means in this context. We will stick with these two: durability and reduced drag. And in both cases, there is no universal answer. It depends on the design. It is not possible to derive these characteristics based on a single attribute: silence. Indeed, it is also a characteristic of the design – whether the hub is silent or not.

Recently, there was an attempt to introduce retractable “ratchets”. That is, to completely remove whatever contact may be between ratchet parts in the disengaged mode. If there is progress with this approach – drag will be lower, compared with similar ratchet designs. Durability? Hard to say. One can think that ratchets themselves will do better. Possible, yes.

What about that retracting mechanism? How durable it will be? What about ratchets: how well they will operate? Especially at the “about to engage” point? Without an in-depth analysis of a particular design and its embodiment, it’s hard to tell.

On the other known design, there is a one-way bearing type. If one were to use bearings theory, drag losses depend on the bearing’s diameter. It is not the only component, but it does contribute there. The larger it becomes the greater the resulting drag losses. The diameter of such mechanisms is comparable, or larger, to the size of a typical bearing used in rear hubs. Thus, it’s like an extra bearing that one needs to account for from a drag loss perspective. We haven’t done our own study to suggest any real comparative data.

In our view – it is not obvious, to say the least, that such designs bring a benefit there. What about the durability of such designs? Even though hardened steel is the material of choice there, it still wears out. And we all know that weight is an important factor. Thus, making a part “beefier” as a way to drive up durability is hardly an option. Wear hardening caused by normal operations gradually kicks in. It may not render the part unusable but will affect performance. E.g. engagement angle increases over time. Again, one needs to put things into perspective. These systems are durable in our view. At the same time, we do not consider that the design “per se” offers higher durability.

Stan’s: The main appeal of silent hubs seems to be creating a more quiet, natural riding experience. How you go about making a hub silent depends on engagement type, subtle design features, and component qualities. Some quiet hubs drag more than some loud hubs, and there’s no actual correlation between noise reduction and drag reduction or durability.

With the new M-pulse, we didn’t set out to prioritize the sound. We thought some degree of “hub sound” was acceptable, with the main focus on exceptional durability, and relatively low drag. Form followed function for us, and function wasn’t silent.

Got a question of your own? Click here to use the Ask A Stupid Question form to submit questions on any cycling-related topic of your choice, and we’ll get the experts to answer them for you!

The post AASQ #156: Are silent hubs better? appeared first on Bikerumor.

We know, there’s no such thing as a stupid question. But there are some questions you might not want to ask your local shop or riding buddies. AASQ is our weekly series where we get to the bottom of your questions – serious or otherwise. Hit the link at the bottom of the post to submit your own question.

This week we’re turing our attention to the asphalt, looking at why road bikes with rim brakes and thru-axle wheels are a rather uncommon sight. To tackle the question, we have experts from Felt Bicycles and Argonaut Cycles. They are:

• Jeremiah Smith, Engineering Manager at Felt Bicycles
• Ben Farver, Owner of Argonaut Cycles

Why can’t I have a road bike with rim brakes AND thru axle wheels?

Felt: Another way to consider this question would be to ask, “Why do road bikes have disc brakes and thru-axles”? There is no technical reason why they could not have rim brakes and thru-axles or, alternatively, disc brakes and quick releases. Disc brakes with quick releases were utilized on mountain bikes for quite a few years. The push for disc brakes on road bikes came around the same time that mountain bikes were moving away from quick releases and to the 142×12 thru-axle standard. Thru-axles were developed for mountain bikes, as quick releases did not offer a stiff enough interface between the wheel and frame, especially on full-suspension mountain bikes.

Road bikes traditionally used 130 OLD (the distance between the inside faces of the dropouts, sometimes referred to as “spacing”) quick release hubs, while mountain bikes had used 135 quick release hubs. While there were some rare 130 disc hubs that were made for some early disc road and cyclocross bikes, they were not ideal. Because the disc brake mounting flange occupies a substantial area, the spoke flange has to move towards the center of the hub, which decreases the spoke angle and the strength of the wheel. The 135 OLD width hubs are wide enough to support a disc brake flange and still maintain acceptable spoke angles. (Note that 142×12 is the same 135 OLD width hub with different end caps for thru-axles.)

Road bikes could have moved to 135 quick release hubs, but because mountain bikes were already moving to thru-axles and all of the manufacturers were gearing up for that, we got 142×12 as the standard for all road and cyclocross bikes. While wheel changes aren’t quite as fast with thru-axles, they offer a much more robust connection between the frame and wheel.

So, back to the original question. “Why can’t I have a road bike with rim brakes and thru-axle wheels?” As I explained above, it is partially about timing and functionality. The timing part is that the push of disc brake-equipped road bikes came at a time when mountain bikes had, for the most part, moved to 142×12. Because it was an existing functional standard it was just adopted for disc brake-equipped road bikes. The functionality issue is that thru-axles never offered a significant enough advantage for road bikes on their own to cause the industry to move to it. The change had to come along with disc brakes as the primary driver.

Argonaut: From a performance standpoint there’s no reason you can’t run a thru-axle on a rim brake bike. It’s not like the axle interface would impede rim braking performance. In fact, it would likely be a big improvement.

But, no one makes a thru-axle, rim brake hub, that I know of anyway. I’m not sure if DT-Swiss end caps are swappable between their TA disc hubs and rim brake hubs, but I don’t think so. That being said, I can’t think of a reason you couldn’t build up a rim brake rim around a disc brake hub. You would have a rotor interface hanging out not being used that would be a little weird, but that would hurt anything.

You’d need a custom fork, though, maybe Wound Up would make one for you? The rear spacing is easier, but again, you’d need a custom frame that could take a 142mm x 12mm thru-axle. I bet Aaron at Mosaic would build you one! Haha. Where there’s a will, there’s always a way.

Got a question of your own? Click here to use the Ask A Stupid Question form to submit questions on any cycling-related topic of your choice, and we’ll get the experts to answer them for you!

The post AASQ #155: Why can’t I have a road bike with rim brakes and thru-axle wheels? appeared first on Bikerumor.

We know, there’s no such thing as a stupid question. But there are some questions you might not want to ask your local shop or riding buddies. AASQ is our weekly series where we get to the bottom of your questions – serious or otherwise. Hit the link at the bottom of the post to submit your own question.

This week, the good folks from Race Face, absoluteBLACK and Wolf Tooth Components are on hand to answer your questions on all things oval chainring. How oval is too oval? Does an oval chainring expedite wear on other components of your drivetrain? These questions and more are answered by the following:

• Technical Department at absoluteBLACK
• Doug Chalmers, Design Engineer at Race Face
• Kurt Stafki, Marketing Manager at Wolf Tooth Components
• Lori Barrett, Managing Director at Rotor Bike

What’s the advantage of a double-cam/twin-cam chainring over a regular oval chainring?

Editor’s Note: We did contact the folks at Cruel Components and Osymetric for comment on this but they weren’t available to provide a response at this time.

Wolf Tooth Components: Going to a more complex shape allows for further adjusting of the torque required based on the crank arm position, but this will lead to noticeable and unnatural transitions through the pedal stroke. While this may work fine in controlled environments (like trainers or a flat time trial), you don’t want abrupt changes when dealing with mixed surface riding – gravel, adventure, MTB, and most roads.

Also, to be clear, the mathematical shape used to define oval rings is actually an ellipse, which is why Wolf Tooth chainrings of this shape are called PowerTrac Elliptical chainrings. To nerd out a bit, all ellipses, which are defined as a curve on plane having two symmetric axes, are oval. An oval is defined as a shape that can have one or two symmetric axes. So, all ellipses are ovals, but not all ovals are ellipses.

Race Face: Oval chainrings work by changing the leverage on the chain through the crank stroke. The rider gets a more consistent force at the pedal through the whole pedal stroke. This means they can apply more force in the optimal power zone and less in the dead spots on the pedal stroke, reducing rider fatigue and helping to maintain traction on technical terrain by pedaling smoothly.

Race Face field testing has shown that slightly elliptical style oval rings are the sweet spot for most riders who want to try non-round rings. This relatively slight change in shape doesn’t result in having to learn to pedal all over again and typically results in improved traction and reduced fatigue without feeling odd when spinning fast on smoother trails at higher speeds.

There are specific advantages/disadvantages to more complicated variations of non-round chainring designs but there are technical challenges of meshing the chain to complex shapes as well as mitigating premature wear at sharper transitions on the ring perimeter. If they’re not overcome, there’s a higher potential for chain drop and short ring life. Low aspect ovals are similar to round rings in these respects.

absoluteBLACK: We can’t find any advantage. As a matter of a fact, it is rather the opposite. We have measured over one thousand cyclists in our laboratory (over time) with our state-of-the-art equipment ranging from amateurs up to the Winner of the Tour the France to study bio-mechanical movement. The shape of our oval chainrings comes from the scientific measurements and optimization rather than the “design” preference.

The shape was determined based on the output cyclists give to the pedals which differs between riding styles (e.g. MTB, road, TT) hence our MTB chainrings differ slightly in shape and timing compared to our road version. All of this requires a lot of bio-mechanical knowledge and a very unique tool to record 3-dimensional forces and torques at the pedals. In our Laboratory in Slovenia we have a bio-mechanical scientist and proprietary state-of-the-art equipment to do just that. More information can be found on our page under “science” tab.

Rotor: First, let’s clear up the difference between an oval ring, like the ROTOR Q Rings, and a double cam chainring: an oval ring has a single percentage curve (ovality) for the whole ring, where a double-cam chainring has a percentage ovality on either end with a connection in the middle that is lacking a matching curve.

Since the majority of studies show a greater benefit to oval Q Rings, ROTOR doubled down on this technology with our Optimal Chainring Position (OCP) system. This is a patented technology allowing riders to position the oval ring in accordance with their point of maximum power in the pedal stroke. With the ability to adjust the position of the oval, the rider is able to take full advantage of the reduction of drag in the pedal stroke’s dead spot and fully capture the additional leverage provided by the extended part of the oval.

Do oval chainrings put undue pressure on a derailleur clutch, thus leading to expedited wear?

absoluteBLACK: Well-designed oval chainrings have the same pull of the chain at every stage of the crank revolution. Our oval shape is a geometrical ellipse which means that no matter how you cut it through the middle it always produces 2 equal parts.

In real life however, there are some manufacturing tolerances on the crank – chainring connection resulting in small variation. This variation, however, is well within the engineered “play” of the clutch. We have been selling our oval chainrings for over 9 years now and still haven’t heard of a single clutch being worn out because of them. This is simply an unsubstantiated myth that is circulating on the internet since the clutch mechanisms entered the market and has been repeated ever since.

Wolf Tooth Components: This is a good question, but oval chainrings do not lead to expedited wear on a derailleur clutch. The beating that the clutch takes trying to control the chain over bumps far exceeds what a bit of cyclical movement does to it. There are some pretty great high-speed videos of suspension bottom-out that show how far the rear derailleur is whipped around–that is a worst-case, but imagine thousands of smaller impacts.

Rotor: While there can be a slight amount of movement in the derailleur cage with an oval ring, there is more movement demanded by variety of inherent bike movements, such as shifting on a standard round ring setup, a full-suspension bike moving through its travel, or the vibration accorded a hardtail or rigid bike passing over rough terrain. We have a number of customers who love riding an oval ring on a single speed cyclocross or mountain bike setup with no noticeable problems in chain tension.

Race Face: Depends on how sensitive the clutch design is. Most have a slight amount of lash that allows for an oval. Ovals do not vary the chain length as much as is commonly thought. The number of teeth on the chainring always remains constant.

However, a result of having a ring with a changing radius is a very, very small change of the angle at which the chain leaves the cassette and arrives at the chainring (and the distance the chain is having to span). An angle change of this amount has a nearly negligible effect on the total length of the chain between these points and does not result in excessive clutch use. It might be unintuitive, but it is possible to run an Race Face elliptical oval ring on a single speed bike.

How oval is too oval?

Race Face: This is subjective, but we have found that around 10% ovality is a reasonable number for most users, e.g., a 32t ring with 10% ovality has a major radius of a theoretical 33.6t round ring and a minor radius of a 30.4t round ring, a 3.2t total radius change). However, some riders run highly specific rings with parabolic paths, perhaps due to asymmetric leg injuries etc. And, some folks just prefer good old round rings!

In addition to ovality, timing must also be considered – relative angle between the major axis of the oval ring and the crank arm. The correct timing will depend on BB drop, seat tube angle, reach, and if the bike has an idler or not. Between 110-115° typically works for a standard drivetrain on an MTB with current geometry. Almost all MTB oval rings are in this range. Gravel and road rings may be different due to the different riding positions, so the rider is pushing on the crank at a different angle relative to the ground. 

Note: If you have an idler, you must rotate the oval forwards to match the angle of the chain arriving onto the ring, treat the idler as the “cassette.”  

Rotor: The studies we have consulted indicate there is a “sweet spot” of ovality, currently adopted at 12.5%. The point of an oval ring is not that one feels the oval, but rather that the pedal stroke becomes smoother with no conscious effort from the rider. It’s worth noting that the original ROTOR Q Rings ovals were at 10% ovality, with an option for QXL at 16%. After more research showed that we could improve upon the positive impact for pedal stroke efficiency, we adjusted all ring production to the more effective oval percentage of 12.5% and discontinued the rings that provided less advantage.

absoluteBLACK: There is no single answer that determines it because Ovality is a function of measurement and optimization per size and per intended use. It strongly relates to the first question. We performed over one thousand measurements and tested various ovalities throughout our development. We managed to determine the optimal ovality and timing based on objective scientific optimization.

As a rule of thumb, it is usually too oval (or not oval enough) if a designer does not have any bio-mechanical data from cyclists to base their knowledge on. There is also a second aspect that is just as important as the amount of ovality but sadly is often neglected. It’s the timing – when in the crank cycle the chainring has the biggest radius. You need to get those two aspects right in order to make a great oval chainring. 

Wolf Tooth Components: The fundamental idea behind oval chainrings is to translate human biomechanics into power for pedaling a bike. An oval chainring shape syncs natural movements with crank arm positions for efficient pedaling. When the crank arms are near vertical, you have less leverage and therefore you can’t transmit as much power to the pedals. An oval chainring provides more mechanical advantage in that portion of the pedal stroke, e.g., like having a chainring that is two teeth smaller.

Conversely, when the crank arms are near horizontal, you have more leverage and can transmit more power to the pedals. Based on those positions, you’d want a smaller chainring for when you have less leverage in the vertical crank arm position and a larger chainring when you have more leverage in the horizontal chainring position.

Our oval chainrings use a 10% ovality. With this shape, a Wolf Tooth PowerTrac Elliptical 34T chainring behaves like a 32T when crank arms are vertical and a 36T when crank arms are horizontal. This 10% ovality also offers optimized advantages of oval with the main ones being better traction and acceleration form a more even torque profile.

Am I more likely to snap a chain under high torque with an oval chainring as opposed to a round one? As the chain is cycled and, thus, the top chain line is pushed up and down relative to the ground, the amount of chain wrap around the cassette varies throughout the pedal stroke. Can this put more stress on the chain links?

Rotor: Short answer: there is no additional strain on a chain from using an oval ring. One of the metrics of increased performance on an oval Q Ring is improved pedal smoothness, which leads to more consistent and even application of power across the whole drivetrain, including the chain. Something that may be of interest in this vein; ROTOR power meters come with a free INpower software that allows riders to visually see their pedal stroke efficiency. It quantifies the smoothing of power output offered by a Q Ring.

Wolf Tooth Components: An oval chainring will not add any stress to the chain links beyond that of a round chainring. If anything, the chain will be stressed less with more even torque applied at the cranks (and thus more even pull force on the chain). When talking about the cassette, much like the clutch explanation, that chain is bouncing around already so the exact tooth engagement is dynamic from riding. Any additional movement of the chain from ovality as it comes off the top of the cassette is negligible.

absoluteBLACK: The amount of chain wrap does not vary on the cassette nor on the chainring in any meaningful way (comparing round vs oval). The angle of the chain leaving the cassette varies less than 2° – this is a negligible difference, meaning there is no correlation between the shape of the chainring and the likelihood of snapping the chain.

Regardless of the chainring shape, chains may snap in general if the quick link/pin was wrongly installed. But the most common cause is actually shifting under the full load. When a chain changes gears on the cassette under load, chain plates are pulled from an angle while being hooked only on 1-3 teeth, and this may lead to decoupling of the outer plate from the pin. So, the best way to avoid potential chain failures is simply to avoid shifting under load. During gear shifts just reduce the load on the crank for one full pedal revolution. 

Race Face: No. Race Face oval rings only increase the mechanical advantage of the rider in the portion of the pedal stroke where they are weakest, sometimes described as the “dead spot,” when the rider’s feet are at the top and bottom of their stroke. Using an oval chainring will typically result in more consistent chain tension through the pedal stroke compared to a round ring, due to the balancing effect of the ring leverage varying inversely with the rider’s power stroke position.

In answer to the question on chain-wrap, a change in chain-wrap of this small amount does not result in a notable change in the stress the chain links experience. The key is to have smooth transitions between each link, and a standard oval is one of the most efficient ways to do this on a non-round ring. 

Got a question of your own? Click here to use the Ask A Stupid Question form to submit questions on any cycling-related topic of your choice, and we’ll get the experts to answer them for you!

The post AASQ #154: Your Oval Chainring Questions Answered by absoluteBLACK, Wolf Tooth, Race Face and Rotor appeared first on Bikerumor.

We know, there’s no such thing as a stupid question. But there are some questions you might not want to ask your local shop or riding buddies. AASQ is our weekly series where we get to the bottom of your questions – serious or otherwise. Hit the link at the bottom of the post to submit your own question.

This week we’re taking on some serious suspension tech, delving into the world of rebound and compression damping adjustments. What actually happens inside the cartridge when you turn those external adjustment knobs? How does that change the suspension’s behaviour? Should you lock out your fork while climbing? What to do when the external adjustments simply aren’t enough? These questions and more are answered by the following experts:

• Giancarlo Vezzoli, Luca Rossi and Andrea Terzi at Formula
• Cornelius Kapfinger at Intend Bicycle Components
• Matt Hornland at FOX and Marzocchi
• Engineering Office at BOS Suspension

What actually happens inside a fork damper cartridge when you turn the compression and rebound dials?

BOS Suspension: In 75% of the technology, the clickers are moving a needle which has a cone form. This will affect the bleed section of the adjuster you are playing with. Some of the technologies have a valve and a spring. When you are changing the clicks, you are adjusting the preload of the spring and this will affect the threshold of the valve’s movement.
To make it simple, the adjuster offers more possibility to the oil for avoiding the piston and the shim stack resistance.

Intend: The so-called “Low Speed Adjusters” are only an orifice with adjustable size. But, the size does not change while you are riding. You can see that here on the example of my rebound assembly.

There is a small hole, which is open in the first picture (left) and closed in the second picture (right). The red adjuster on the inside is going to be threaded in when you turn your rebound adjuster.

FOX: The exact way this works will depend on your fork, but the simple answer is fluid travel is modified. Low-speed compression and rebound is usually controlled by using an orifice valve. This controls small amounts of oil that is allowed to flow freely around the shim stack. High-speed compression and rebound is usually controlled by using preload. This controls oil flow through shims that block ports on the piston by changing the force required to initiate the use of this valve. With something like FOX’s Variable Valve Control, the adjuster knob changes the leverage that the shim stack has over the leaf spring, instead of preload, reducing harshness as the initial force doesn’t change, but the slope of the damping curve can change.

Formula (Andrea Terzi): By turning dials in a fork cartridge, we can reach the best feeling for every condition and terrain with our bike. Technically, when we use it, we modify an oil flow that passes through a hole.

The mechanism of regulation is traditionally operated by a needle (conical or ogive shape) which flows in rectilinear motion controlled by a positioner. The more you turn the knob (in clockwise direction) the more the needle closes the hole.

This increases the pressure value with the result to force the oil to flow through the piston holes, elastically deforming the shim stack. Deforming shims requires more force instead of passing through a free hole, so for this reason we feel the fork is harsh when we close the compression register.

My fork doesn’t rebound fast enough at the low pressures I need to run to achieve the desired 25% sag. I find it packs down, even with the rebound set to fully open. What can be done?

Intend: In this case, the rebound tune is to hard for your riding weight. This is a common problem with stock suspension. Even if you have a high-speed rebound adjuster it can be that the rebound stack does not fit. In this case it is best you take it  to a tuning shop and get a proper setting according to your weight. Or you can simply use thinner oil in the damping. This also influences the compression damping, but is a cheap way to solve the problem. Or, you can buy an Intend fork. We can tune the fork based on your weight from the beginning.

FOX: Unfortunately, there isn’t a simple answer for this one. What fork is it? When was the last time it was serviced? There are lots of factors at play and they would benefit from speaking to a service tech at their LBS or touching base with a service tech at FOX about what they might need to do.

Formula (Luca Rossi): We know there are many riding styles and some riders don’t find the “perfect bike” until they adjust it for the way they ride. It is precisely for this reason that we also have a cartridge with a high rebound flow in the spare parts list. While you wait for the cartridge with faster rebound, though, you can try to change the CTS to get a more shifted damping curve at high speeds (like a blue or a red one) or add more than one NEOPOS to keep the fork higher.

BOS Suspension: Changing the clicks or the shim stack of the rebound will not always be enough in this case. Basically, you will have to change the balance of compression/rebound to be able to reach the right dynamic ride height with lower pressures in the cartridge or with lower spring rates. You will have to compensate for the lack of support from the spring by adding some compression damping rate.

Should I fully close the compression dial on my fork for climbing?

FOX: This depends on your fork and your desired ride quality. On a more technical ascent, we would recommend riding in trail mode, or slightly less than “locked out” to get the benefit of some bump compliance. If you’re climbing on the road or on a fire road, locking it out is great.

Formula (Giancarlo Vezzoli): I assume we are talking here about a fork (or shock) without a lockout; switching to a firmer compression helps if it acts on low speed damping. However, it is really unusual because actuating a compression knob is not really an “on-the-fly” operation; it usually requires the rider to stop riding and adjust. Moreover, some of the products on the market don’t have a compression knob, so the operation requires a tool (which hopefully you’re carrying all the time).

You will need to set it back before the descent, to a proper value (remember it or sign it on the suspension chart, usually present on the fork). That being said, we at Formula strongly believe in lockout, very firm actually: it drastically improves the climbing performance, and is available on almost all of our suspensions products.

The Formula blow-off valve prevents suspension damages even with the lock-out on, and furthermore saves you in case you forget to unlock it before a descent.

BOS Suspension: It depends how the dials affect the damping. If your fork is too stiff, you will lose stability on the uphills. The transmissibility in the frame of the holes, bumps on the ground will be too high. The aim of closing compression is to have a stiffer fork and avoid losing energy. An example, in hard slopes, at low speed, your fork should work to avoid wheelie.

Intend: You can do that, but there are no figures that show you can save a significant amount of power if you lock out your fork. If you are in search of a single Watt, then yes, probably. For the normal rider, it does not really matter.

Is there any reason not to run HSC and LSC damping fully open while descending?

Formula (Luca Rossi): Yes, if you keep the compression with zero damping (fully open) on the descent, in order to have support and prevent diving on the front you would have to increase the elastic force (air or spring). At this point, when the track changes slope and returns to the flat or uphill, you will find a vehicle totally unbalanced and loaded on the rear.

Intend: Depends on your fitness. Some riders say, they are faster with harder damping. In this case it is counterproductive to open your compression damping. But, more compression damping also means more fatigue on your hands. If you are riding the whole day in a bike park, it is nice to get the first two runs at full speed with hard compression, and then you are done and… in this case it is better for your average riding to open the compression to be able to ride the whole day, not only the first two runs.

BOS Suspension: There are no reasons at all to go this way. First, you lose the support that you can get from the hydraulics; this will affect the dynamic ride height a lot.

Secondly, and most importantly, softer doesn’t mean moire comfort. Your bike needs to have a minimum of damping. There is a range of damping where the suspension works best depending on the type of tracks. Being too soft or too stiff is uncomfortable for the rider and not good for the tire grip. You have to find the “sweet spot”. Getting the tire on the ground a maximum of the time and maintaining the ride height is the key.

If you are too soft you can have some overshoot of the wheel. This means your suspension will use more travel than needed. Your tires will spend lots of time in the air. The bottoming-out will be an issue as well. A the opposite end of the spectrum, if you are too stiff, you will transfer the energy to the chassis and your tires will be in the air for most of the time as well.

Why do forks come with such a massive range of compression and rebound adjustment when the vast majority of settings make for a completely awful ride feel?

BOS Suspension: The reason is to be able to cover a large panel of riders and track type. This will depend of the weight of the rider and the riding style, for example. As there are a large range of pressures or spring rates, the adjusters allow the suspension to adapt to the widest range of riders, even if each rider will use a small range of the adjusters.

FOX: At FOX Factory, we engineer and build race suspension. The massive range of adjustments are available to allow for the puzzlers and tinkerers to fine-tune their suspension through testing, training and observation. While not every rider will need this, we want our end users to have the same range of adjustment that our racers do so they can fine tune themselves; HSC, LSC, HSR, LSR, with clear settings to achieve the exact feel you want every time. It’s the same tuning philosophy we take.

Formula (Giancarlo Vezzoli): Suspensions are designed for a very wide crowd, with multiple riding styles, skills, weights, fitness, bike type and trail/terrain conformation, not to mention the temperature, altitude and latitude. The meaning of ample range settings is to let people find their preferred feeling, which is obviously not unique even in the same exact conditions. You surely have experienced the ride of your friend’s bike and judged it unusable. You for sure would need to change the settings between a hot summer and a freezing winter; the oil behavior, the rubber seals, the lubes in general work differently if you drop the temperature by 20°C.

Actually the adjustment range is never enough: indeed, people need to work on the shim stack in order to tune the suspension even more finely; that’s why here at Formula we introduced the CTS system, the simplest way of tailoring the suspension behavior without being a pro mech, at a very limited cost.

Intend: This is important to give the customer the feeling that the adjuster works.

Let’s take the following as an example: you buy a fork for a normal average rider weight of 70-90 kg and it has 4 clicks of rebound adjustment.

If you are 80kg, two clicks are perfect for you, and the fork feels nice. If you are 70kg or 90kg and you need 0 clicks (=open) or 4 clicks (=closed), respectively, to adjust it to your riding style. This may feel strange, though, because you get the feeling that you are already on the limit of the fork’s adjustments.

Really, you want to have the feeling, that whether you weigh 70kg or 90kg, that you can run 2 of 8 clicks as the lighter rider, or run 6 of 8 clicks for the heavier. In this scenario, you will feel you are more in the middle of the range, although you will never use 0, 1, or 7, 8 clicks (respectively). The possibilities give you confidence that you are in the middle of the range and the setting is a better fit for you.

Marzocchi: Simplicity is why Marzocchi has a more “set it and forget it” tuning philosophy. We don’t count clicks, and we think that more time fiddling with adjustments means less time shredding the trails. We keep adjustments simple with intuitive compression sweep, from locked-out to full open and simple rebound adjustment covers the range from fast to slow rebound for a full range of rider weights and preferences without over complicating things.

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The post AASQ 153: How do Suspension Rebound and Compression Damping Adjustments Work? appeared first on Bikerumor.

We know, there’s no such thing as a stupid question. But there are some questions you might not want to ask your local shop or riding buddies. AASQ is our weekly series where we get to the bottom of your questions – serious or otherwise. Hit the link at the bottom of the post to submit your own question.

Welcome back to the Bikerumor Ask A Stupid Question series. This week, we’re taking a closer look at the lesser-spotted usage of Truss Systems in bicycle frame design. One of our readers is interested to know why the use of trussing, in particular internal trussing, hasn’t been more widely taken up by the industry. To tackle this question, we’ve approached several frame designers who have, in various forms, used a Truss System in production of their frame. Having made use of Truss Systems themselves, they are perhaps best placed to comment on why this unusual frame design has remained, well… unusual.

• Sam Wilding, Director of Sales and Engineering at IsoTruss
• Ryan Johnson, Frame Designer at Galaxy Gear Works
• Bernd Iwanow, Frame Designer and Engineer at Frace Bike

Why is there no internal truss system in modern bike frames? Yes, we need to keep the surface smooth but why isn’t there more talk about individual strands of fiber taking a carrying load in a truss system? There could be potential weight savings in stiff areas like BBs and head tubes.

IsoTruss: Truss systems do offer advantages in weight and stiffness, but there are some challenges incorporating the truss system with the rest of the bike frame. First, some advantages. When it comes to hollow composite tubes/sections, the most efficient designs have thin walls and a large surface area. This makes the walls prone to puncture and such structures can be prone to shell buckling. Think of an empty soda can. You can stand on it, but the slightest touch to the wall of the can results in collapse.

With a truss system, individual members of the truss are more robust than the thin walls of the tube and less damage prone. The failure modes of a truss are typically easier to predict, too. Trusses are more efficient, from a strength-to-weight standpoint, than hollow tubes resulting in stiffer, lighter structures.

Now some of the challenges. The most pressing challenge, and the likely reason truss systems haven’t been adopted more readily, is manufacturing. The truss sections require complex manufacturing. Each section is made separately and then integrated with other frame components manually. This process is slow and expensive. For many, the additional cost doesn’t justify the boost in performance. Investment into better manufacturing methods would likely yield more consistent, less expensive products.

Galaxy Gear Works: First and foremost, any internal trussing/bridging/etc may be very difficult or impossible to accomplish in a meaningful or cost effective way on any production scale. The existing production methods that produce thin-walled metal tubing common in the bicycle industry (aluminum, steel, titanium, or otherwise) preclude the inclusion of internal features. While we can manipulate wall thickness with butting processes and shapes with various forming methods, we can only produce hollow tubes i.e. no trussing. Carbon tubing production as we know it in this industry would also (usually) preclude the creation of internal features whether the tubes are formed on a mandrel or inside a mold.

However… I have seen internal bridging in the steerer on a few carbon forks in the last few years. I don’t believe it is common practice. Why not, you might ask? Firstly, I’m certain that it’s an enormous pain in the ass to mold the steerer with a web dividing the tube. Layup precision and laminate compaction would be complicated to say the least. Bladder equalization and post-cure removal could also be significant hurdles. Here’s another thought that is perhaps the real reason why it is not common; a fork steerer has to meet certain structural criteria that perhaps define the wall thickness to a degree that an internal web/bridge is superfluous. Shear and bending forces at the fork crown aside, the top of the steerer tube has to resist the clamping forces of the stem and ham-fisted mechanics.

Even supposing everyone ritually abides by the manufacturer’s torque specifications and uses a torque wrench to install the fasteners, it has to withstand a fair bit of crushing force. Add the real-world stresses with the “fudge factor” that the engineer calculates in there to keep the lawyers happy, and the steerer has to have a pretty hefty wall – certainly burly enough to handle normal torsional, shear, and bending loads as well.

The steerer also has to have that “hefty” wall thickness through so much of its length to accommodate the stem clamp height for an extreme range of bike sizes, assuming a production fork. So… does it really make any sense for internal trussing/webbing/bridging on a production made fork? In my opinion, it would require too much effort for far too little reward. I don’t believe it could add measurable performance benefits or reduce weight at a meaningful level.

I have also seen a few examples of internal features on steel bikes, and I’m currently riding an MTB with internal bridging in the chainstays. The point of the aforementioned features is stiffness. Dario Pegoretti created the Big Leg Emma with a series of flat sheet bridges in the downtube. They are inserted into slots cut into the sides of the tube, brazed into place and covered with a tidy, brazed-on gusset. You can see these features clearly on the model page on the Pegoretti website.

The tubes on this bike are fairly large in diameter for steel tubing, and I’m sure that the walls are pretty thin. In my opinion, the bridging plates are long enough (in reference to the long axis of the tube) to act as a truss to increase the tube’s resistance to side-to-side bending forces i.e. all-out sprinting for city limit signs on Tuesday nights. How much stiffer is it due to these internal features? I have no idea. It could be measured of course.

My current MTB was built as a “shreddy hardtail” so it needed to be somewhat burly. Strength and stiffness were paramount, and those attributes had to marry with a kinda short chainstay length and 2.8″ tires. With all that in mind, the chainstays were pretty narrow where they were formed around the tire. I felt like this narrow cross section wasn’t going to produce enough lateral stiffness in the stays.

Part of my concern was the real possibility of tube deformation and bending under pedaling loads. Like the advantages I believe to be present on the Pegoretti downtube, I think I added strength and stiffness to the tubes by adding horizontally oriented plate bridges across the interior of the narrow, forward portion of the stays. I executed these additions by slicing the tubes, inserting the sheet-metal plates (about four inches long), and welding the plate’s edge along the tube intersection.

Now we ask the question, “was it worth all the effort?” I don’t know the answer. I didn’t do any lab type testing or calculations. I’m no engineer. What I do know is that the bike rides well and is going strong after more than two years of hard riding. I also know that I damn sure didn’t save any weight by adding those bridges.

Is it possible that internal bridging/trussing could allow thinner walls on the tubes? I’d say heck yeah! How would we do it? Perhaps 3D printing somehow rather than laborious hand work or a combination of both? And would it come at a cost to durability and therefore practicality? The answer might be yes. Use the massive, but not surprising proliferation of carbon repair services springing up all over the country now that the volume of out-of-warranty carbon bikes has reached critical mass as evidence. The tubes on ultralight carbon road bikes don’t need to get much thinner unless we see more volume of tougher materials like Dyneema incorporated into the laminates. That stuff is expensive though!

In the real sense, internal trussing does not commonly exist in this industry. With carbon production frames routinely coming to market below 900g, is there really a need to try and make them lighter? I’m not sure. And more often than not, these ultralight bikes are plenty stiff thanks to high modulus carbon and smart laminate engineering.

Frace Bike: A tube compared to the truss system is having always less weight for having the same stiff characteristic. So it is for sure more weight saving to have a tube – but it is also a lot more boring. Everybody is doing tubes – but we want to have something different from all the others. And, for having a fully milled frame out of aluminum there is no other opportunity than choosing such a style as the truss system. But this truss system is more expensive – but it is looking great. Sure you have to pay more but then you are getting a unique style.

Got a question of your own? Click here to use the Ask A Stupid Question form to submit questions on any cycling-related topic of your choice, and we’ll get the experts to answer them for you!

The post AASQ #152: Why is there no internal Truss System in modern bike frames? appeared first on Bikerumor.