Myth 4: Stiffer Frames Are Faster

To celebrate 15 years of Bicycle Quarterly, we are examining 12 myths in cycling – things we (and most others) used to believe, but which we have found to be not true. Today, we’ll look at frame stiffness.

When we started Bicycle Quarterly, the thinking about frame stiffness fell into two camps. The majority of cyclists subscribed to the notion that frame flex wastes energy and that stiffer frames are faster. A few scientific types believed that the energy lost to frame flex was small, and thus frame stiffness probably does not matter. There were a few builders, like Bill Davidson, who extolled the ‘lively ride’ of lightweight tubes, but they were mostly ignored.

At Bicycle Quarterly, we mostly subscribed to the notion that it didn’t matter. And so we were happy riding relatively flexible frames… Sure, stiffer frames might offer marginally better performance, but seeing pros win on Vitus and Alan frames that had a reputation for being ‘noodles,’ we figured that if a frame was stiff enough for Tony Rominger and Sean Kelly, it would be stiff enough for us.

Then we tested a bike that didn’t perform well for us. It seemed to bog down on the climbs. It was harder to maintain a high cadence. It wasn’t as much fun to ride. I described this to the framebuilder Peter Weigle, adding: “The frame is made from heavy-wall, oversized tubing, so it must be plenty stiff. I can’t figure out why it doesn’t perform.” Peter paused for a while, then he said: “What if the frame is too stiff for you?”

That was something I’d never considered! It was like saying that my bike was too light, or that I had too much power. But it got me thinking.

Along came another Bicycle Quarterly test bike (above). This one performed better than expected. It wasn’t particularly lightweight, and our initial expectations weren’t all that high. And yet, whether it was me or Mark (our second tester) riding it, this bike climbed faster than our other bikes. It turned out that it was made from very thinwall, and thus flexible, tubing.

So we had tested one bike that was stiffer than our own, and it didn’t perform as well. A second one was more flexible, yet it performed better. Even more startling was the difference in feel. On the flexible bike, pedaling faster didn’t seem as hard. We were out of breath, but our legs didn’t hurt. Once we got in sync with the frame, its response to our pedal strokes felt like a boat rising out of the water, going faster with only a little extra energy input. “You mean, it ‘planes’,” said Matthew Grimm of Kogswell, when I described the phenomenon to him. Deciding that the phenomenon needed a name, we used the term ‘planing’ to describe it.

We could only guess at the physical explanations for what we observed, so a term that was purely descriptive of our observations seemed best and most honest. Sort of like saying that a bike ‘flies’ up a hill, when in reality, its tires don’t leave the ground…

How to test whether our experience was real, and not just our perception? (Perhaps Mark and I just liked red bikes?) All the other magazines were still talking about ‘laterally stiff and vertically compliant frames’ as the ultimate goal… We decided to do a double-blind test with four identical frames, made from three different tubesets. (The duplicate frame served as a control.) Apart from the top and down tubes, the bikes were identical down to the last component. Their weights were equalized to make them truly the same – except that their flex characteristics were different.

The only way to identify them was by their stem cap, and that was switched by the test adminstrator between test runs. And of course, the testers weren’t allowed to talk to each other until the experiment was unblinded at the very end. This test was a huge (and expensive) undertaking for a small magazine, but we felt it was important to do this right.

The results confirmed our previous impressions: Two of our three testers could identify which frame they were riding with 100% accuracy, just based on how the frames performed under hard pedaling. Not only that, these riders were consistently faster on the more flexible frames. Power meters showed that they put out up to 12% more power on the frames that ‘planed’ best for them, yet they felt easier to ride hard. (Our third tester couldn’t tell the – very small – differences. All the bikes in this test were relatively flexible by today’s standards.)

Whether it’s 12% more (for Mark) or a bit less (for me), the difference in power output was very significant! What is happening when a frame planes? A frame that is too stiff apparently ‘pushes back’ against the rider’s pedaling. The rider cannot apply maximum power during the downstroke before their legs start hurting. Imagine pushing against a brick wall – the wall doesn’t move, so no work is done, yet your legs fatigue quickly.

If the bike ‘planes’ in sync with your pedal strokes, then your legs no longer are the limiting factor. Now your cardiovascular system determines how fast you can go: Your maximum heart rate is the limit.

On the stiffer bikes, our legs hurt, but we never reached our maximum heart rate. On the more flexible bikes, our legs didn’t hurt, but we were completely out of breath when we reached the top after putting out significantly more power on the climb.

In the decade since we published our double-blind tests, the belief that stiffer frames are better has lost a lot of traction. Experts finally have tried to measure the energy lost to frame flex, and they came up empty-handed. When Damon Rinard, Road Engineering Manager at Cannondale, proclaims, “I no longer believe that the ultimate rigidity defines the ultimate bike!” you know that the world is changing.

The challenge for the future is to fine-tune frame stiffness to the rider. It’s not simply that ‘more flex is better.’ Our tests indicate that more powerful riders may benefit from (slightly) stiffer frames. It all depends on your pedal stroke and power output.

Our subsequent research shows that flex needs to be in the right places for the frame to get in sync with the pedal strokes, so that the rider can reach their maximum power output. We now realize that the frame doesn’t just serve to connect the parts, but that it is literally the heart of the bike. Like the right amount of flex in a gym floor allows you to jump higher, or the right amount of flex allows pole vaulters to reach incredible heights, the right amount of frame flex allows cyclists to reach their maximum potential.

Further reading:

Acknowledgments: We thank framebuilder Jeff Lyon who made the frames for the double-blind test, Hank Folsom of Henry James who donated the True Temper tubing, and Hahn Rossman who administered the experiment.

Posted in Bicycle Quarterly Back Issues, Testing and Tech | 40 Comments

Back in Stock and New Products

For us, cycling is part of our lives. Our bikes are the most important tools we own. We use them for transportation, and we use them for enjoyment, often combining the two. That means our bikes need to be ready at a moment’s notice. If we can’t get a part, it leaves us stranded. The same applies to most of our customers, who consider the components we sell essential.

That is why we work hard to keep our parts in stock. Usually we are successful, but sometimes an item runs out before a new shipment arrives. It might be that demand is greater than we anticipated. Or there could be a delay at the manufacturer – often because a supplier is running behind schedule. Or a shipment can be held up somewhere. We’ve encountered all these issues in recent months, but we are glad that 98% of Compass parts are back in stock as we prepare our bikes for the next cycling season. Here are a few things that just arrived:

As one of the key contact points, good handlebars are key to a comfortable ride. Many modern bars are very shallow and short, leaving your hands cramped and uncomfortable during long hours in the saddle. The classic handlebars we offer were designed for long days on rough roads, where comfort is paramount. The Maes Parallel (above) give you lots of room to roam, and the Randonneur provides a super-comfortable position on the ramps.

All Compass handlebars are available with 25.4 and 31.8 mm clamp diameters. If you have a 26.0 mm stem, we offer a shim to reduce the diameter to 25.4 mm. We have added wider models, so all our bars now come in widths between 400 and 460 mm.

Saddles are the other important contact point with your bike. We’ve found Berthoud saddles to offer superior comfort and quality. The composite frame is lightweight and flexes a bit to improve the comfort of a traditional leather saddle even further.

Berthoud’s leather quality is second to none. We carry the medium-width touring and the narrow racing saddle, plus a shorter women’s model (above). They are available in different colors, with titanium or steel rails, and also in an ‘open’ version to alleviate pressure. All models are in stock again.

Handlebar tape is a matter of personal taste. Riders with a light touch on the bars often prefer thin bar tape, but most modern tape is heavily padded and too thick for our liking. Maware’s beautiful leather tape is made in Japan from pigskin, so it’s thinner than the others we’ve tried. It’s also superlight, so we used it on the J. P. Weigle for the Concours de Machines technical trials last summer.

Compass now distributes Maware’s bar tape and their leather frame protectors in North America, but the small company was overwhelmed by the demand. Now they’ve caught up, and all products are in stock again.

And if you prefer thicker handlebar tape, we also stock Berthoud’s excellent cowhide tape.

Tires change the feel of your bike more than any other component, and tires are why we got into the component business in the first place: There were no wide tires that offered the ride and performance we wanted. We offer tires in many sizes and models, and a few of them have been in short supply lately. We always make sure that at least one or two models in every size are in stock, so your bike won’t be left immobilized for lack of tires. In time for the new season, all models are on hand again.

We developed the new René Herse cantilever brakes for the Concours de Machines, where the prototypes helped J. P. Weigle’s bike win the prize for the lightest bike. We began to offer the production version last autumn. These are made in small numbers, and sometimes, demand overwhelms supply. They are back in stock, but since they are assembled to order, allow a few extra days for delivery.

We appreciate your patience while some of these components were in short supply. Most parts are back in stock now, and we’ll work on keeping it that way, so you can enjoy your cycling season without worrying about spare parts. Click on the links above for more information, or click here to go directly to

Posted in Uncategorized | 10 Comments

Myth 3: Fenders Slow You Down

To celebrate 15 years of Bicycle Quarterly, we are looking at ‘12 Myths in Cycling’ – things that aren’t quite what we (and most other cyclists) used to believe. Part 3 of the series is about fenders.

Many cyclists here in Seattle install fenders when the rainy season starts, and remove them for the dry summer months. British time trialists even had quick-release fenders that they used on the ride to the start; then they took off the fenders for the actual competition. Our research indicates that this isn’t necessary – fenders don’t slow you down. Here is why:


Bicycle Quarterly did extensive wind tunnel research on the aerodynamics of real-world bicycles. Among things like riding position, clothing and bags, we tested the aerodynamics of fenders. We made a telescoping front fender, which allowed us to test various configurations. Here is what we found:

  • The portion of the fender in front of the fork crown reduces the drag. This is because the tire rotates at twice the speed of the bike, and the fender acts as a fairing that shields it. This works only if the fender extends beyond the top of the tire and drops down in front. (We found that it’s not necessary to extend the fender as far as shown in the photo above.)
  • The portion behind the fork crown adds a little drag. So does a mudflap.
  • The overall effect of the full fender and (small) mudflap neither increases nor decreases the wind resistance of the bike.

If this comes as a surprise, check out modern Moto GP racing motorcycles (below). They all have fenders covering the forward-facing portions of their tires to improve their aerodynamics. Bicycle racing specifically prohibits fairings, otherwise we might see similar fenders in the Tour de France


What about the added weight of the fenders? The best fenders don’t weigh much: Honjo aluminum fenders provide generous coverage, yet they weigh between 423 and 540 g, depending on the width, including all the hardware to attach them. That is roughly the weight of half a bottle of water. The increased versatility of having fenders on your bike is well worth the extra weight – just like a water bottle will slow you down, but you still carry one.

Plastic fenders weigh more – they are more flexible, so they need heavier stays made from steel, whereas the stiffer Honjo fenders use lightweight aluminum stays. Weight-wise, the worst are aluminum fenders with heavy stays designed for plastic fenders – the Planet Bike Cascadia ALX fenders weigh 50% more than their Honjo equivalents, despite offering less coverage.

Reasons not to Use Fenders

There were other reasons why I used to take my fenders off the bike every spring. The plastic fenders I used back then resonated on rough roads. They tended to rub on the tires. The gaps around the tires were uneven, making the fenders look like an afterthought. And every few thousand miles, the rear fender broke and needed replacement. During the summer months, I wanted to enjoy a quiet, smooth and sleek-looking bike. And if that meant getting soaked during the occasional downpour, it seemed worth the trade-off.

With a bike that is designed from the get-go for fenders, like the J. P. Weigle from the Concours de Machines (above), those drawbacks no longer exist. The metal fenders are stiff, so they are quiet. The bike is designed with sufficient clearances, so the tire never rubs on the fender. The fenders follow the outlines of the tires, so they enhance the appearance of the bike. And since the fenders are securely mounted without stresses, they will last as long as the bike. (And the whole bike weighs just 9.1 kg/20.0 lb, so the weight isn’t an issue, either.)

There are some conditions where bikes without fenders work better: deep mud and snow – the same conditions that call for knobby tires. For all other rides, I prefer a bike with fenders, because it gives me the option of heading out even when the weather forecast is uncertain. And I am glad to know now that the fenders won’t slow me down.

Further reading:

Photo credits: Maindru (Photo 1), Alex Wetmore (Photo 2), Motoracereports (Photo 3), Nicolas Joly (Photo 4), Mariposa Bicycles/Walter Lai (@onlywalt, Photo 5).

Posted in Bicycle Quarterly Back Issues, Testing and Tech | 64 Comments

Berthoud Saddlebags

Gilles Berthoud’s are my favorite under-seat bags: lightweight, beautiful and functional. Since using one on a tandem in the 2003 Paris-Brest-Paris, I’ve found them useful whenever my handlebar bag doesn’t have enough capacity, or as the only bag on bikes without a front rack. Berthoud now offers a version that attaches neatly to their saddles with the KlickFix system. We’ve added these bags to the Compass Cycles program.

Like the other Gilles Berthoud bags, the saddlebags are made from waterproof canvas and edged with leather. These traditional materials work well, keeping the contents dry even during my rainy 50-hour ride in the 2007 Paris-Brest-Paris, a year that remains infamous for its wet conditions. The canvas is lighter than most ‘modern’ materials, too – the Berthoud saddlebag weighs just 242 g (254 g for the KlickFix model). And yet it has enough room for two spare tubes, a spare tire, a few tools, a wallet and a pair of arm warmers. The elastic loop closure is easy to open with one hand. I usually run both ends of the elastic loop through the hook for an ultra-secure closure.


The KlickFix attaches to Gilles Berthoud saddles (except the superlight Galibier) with two screws. The saddlebag then slides into the attachment and locks firmly into place. A strap around the seatpost further stabilizes it. To remove it, you open the strap, push the two red tabs inward, and then pull the bag upward. It’s an elegant solution that is simple to use. The second version attaches to the saddle rails of (almost) any saddle with a toestrap.

Like all products we sell, we’ve tested these bags for thousands of kilometers – including the Volcano High Pass Challenge – to make sure they work well even on the roughest roads. I’m sure you’ll find them as useful as I do.

Click here for more information about Berthoud bags.

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Myth 2: Titanium is Lighter than Steel

In part 2 of our series ’12 Myths in Cycling,’ we’ll look at why titanium isn’t always lighter than steel. I can hear you saying, “What? Everybody knows that titanium has half the density of steel.”

That much is true: The same part made from titanium will weigh half as much as the equivalent from steel. But titanium has only half the stiffness, so the part will be half as stiff. To make the parts of the same stiffness, you need to use twice as much material with titanium, and the weight will be equal. The same applies to aluminum, which is one-third as heavy and one-third as stiff. (These numbers are for the high-strength alloys; raw aluminum, titanium and iron are not strong enough to be used for cycling applications.)

For example, if you made a titanium rack, it would weigh the same as a steel rack with the same load capacity. That is why the best racks are made from steel: Other materials don’t offer any advantages.

So why do people use titanium at all? There are other considerations than stiffness. Frame tubes are a good example. The larger the diameter of a tube, the greater its stiffness-to-weight ratio. However, with steel tubes, you run into limits, because a frame tube cannot be made with walls much thinner than 0.4 mm. Otherwise, it becomes too easy to dent, and braze-ons will just rip out of the ultra-thin tube.

A way around that problem is to use titanium. With half the density of steel, if you double the wall thickness, you get a tube with the same stiffness and weight as a steel tube. But you don’t need the walls to be that thick, so you can use larger-diameter tubes. Many titanium frames are both a little lighter and a little more flexible than steel frames. Especially with smaller frames that often can be too stiff for their riders, this can make for a better-performing frame.

The advantage of titanium frame tubes turns into a liability in the one place where you cannot increase the tubing diameter: at the chainstays. Chainstays have to fit the narrow space between the tire and the cranks. Because of this, making titanium chainstays as stiff as their steel equivalents is difficult, especially on a bike with wide tires. My Firefly (above) uses super-beefy chainstays that probably contribute to its excellent performance, but as a result, standard road cranks don’t fit. The photo above shows it with its original CNC-machined cranks, which resulted in a wide Q factor and cross-chaining in the gears I use most. Since then, I installed forged René Herse cranks and filed the ends of the cranks, so I can use a shorter BB spindle. That improved the chainline and (almost) eliminated the cross-chaining, and the Q factor is acceptable, too. Everything had to be optimized very carefully to make it work to my satisfaction, because it is such a tight fit.

Will a titanium frame provide superior performance for you? My Firefly (above) feels very similar to my steel bikes, and the small weight advantage of the frame is lost amongst other factors, such as the added weight of the disc brakes. I love the bike, but a similar one made from steel would perform the same. It may be a different matter for small riders: Even a lightweight steel frame may be too stiff (small frames inherently are stiffer than larger ones). A carefully designed titanium frame may offer more flex in the right places and thus ‘plane’ better…

What about titanium bolts and other small parts? If you just replace a steel part, say a bolt or a bottom bracket spindle, with a titanium one, it’ll be far less strong. That is what Campagnolo found out when they introduced their Super Record bottom bracket – many of these broke. Of course, all parts have a margin of safety built in, and sometimes, you can reduce that margin without failure. A smoother-than-average rider probably can ride a titanium bottom bracket without failure.

The same applies to titanium bolts – if tightened carefully, they can work OK. But then you wonder why you don’t redesign the part with smaller steel bolts. They have the same strength, but go into a smaller hole, which allows you to make the mating part smaller, saving further weight… It’s one example where a well-designed part with steel bolts actually is lighter than one using titanium hardware.

There are a few places where titanium bolts make sense. The eyebolts that hold the brake pads of our brakes (upper bolt in the photo above) are large not because they need extreme strength, but because the post of the brake pad needs to fit through the head. This means that a titanium eyebolt weighs half as much, yet has sufficient strength. And that is why we offer them as an option to reduce the weight of our brakes to just 75 g per wheel. That is lighter than any currently made brake, and yet we don’t give up any strength.

That eyebolt is an exception. Most bolts are dimensioned for the loads they need to withstand, like the bolt that attaches the brake to the pivot (lower bolt in the photo). We won’t offer a titanium version of that bolt because it might break, with disastrous consequences.


Titanium’s stiffness-to-weight ratio is the same as steel’s. Titanium’s density is lower, which can be an advantage when you need or want to make large parts (oversize frame tubes, eyebolts), or a disadvantage when space is limited (chainstays, bottom bracket spindles). Titanium’s lower density saves weight only in places where the dimensions of steel parts are constrained by other factors.

Further reading:

Posted in Framebuilding supplies, Testing and Tech | 60 Comments

Lyli Herse, 1928 – 2018

Lyli Herse would have turned 90 years old today (January 6) – and this post was written to celebrate her life that has inspired so many of us. But alas, I have to report instead that Lyli died on Thursday after a very short illness. Despite the great sadness of losing her, let’s celebrate her anyway, because that is what she would have wanted.

Until just a few days ago, she remained healthy and happy, living with her dog in the house built by her father, the famous constructeur René Herse, near the finish line of the Poly de Chanteloup hillclimb race. These two elements – her father’s bikes and cycling competition – were the defining elements of Lyli’s life.

Lyli first entered top-tier competition at the tender age of 16 years, when she raced in the 1944 Poly hillclimb race, which had categories for professional racers, randonneurs and mixed tandems. She told me: “Some people said that I was too young to compete… The famous Docteur Ruffier gave me a medical exam before and after the Poly.” Her heart rate actually was lower after the race, because she had been so nervous before the event! Partnering with Simon Feuillie, she placed fourth against many strong teams.

It was in the Poly where Lyli made her mark. For nine years, from 1948 until 1956, she was unbeatable in this tough event. Except when the team crashed in the sharp turn at the bottom of the ultra-fast descent… Lyli broke her collarbone, but that didn’t prevent them from finishing the race – only to be disqualified because their rear fender had broken in the crash. Lyli recalled: “My father then designed his fender reinforcement. He didn’t want that problem to happen again!”

She has many memories from that event: “My best captain was Prestat. He worked as a porteur de presse [newspaper courier]. One year, we set the fastest lap of the day, ahead of the professional racers.” The photo above shows her and Prestat during that record-setting ride, climbing the 14% grade smoothly with a single 46-tooth chainring on the front. And they never even used their largest (22-tooth) cog on the rear!

In 1955, Jean Lheuillot was organizing the first Tour de France Féminin, and he wanted Lyli to be part of the international field. It took some persuading, but he didn’t regret the effort: Lyli won two stages and wore the leader’s jersey for much of the race, before finally finishing fourth overall against accomplished riders like the British stars Beryl French and Millie Robinson. Despite her success, Lyli longed for her days as a cyclotourist: “I always felt more at home with the cyclos. The cutthroat competition of racing wasn’t to my liking.”

The best way to stay out of the fray was to ride off the front, which she did with much success, winning no fewer than eight French championships. She wanted to retire in 1966, but she placed third in that year’s championships. She recalled: “I didn’t want to stop racing after a defeat. […] So I said: ‘Papa, I’d like to give it another try.’ Papa had to make some sacrifices to give me more free time for training and such. That year, I won.”

Just before Lyli retired from racing, a few young women asked her if she could coach them. Lyli formed a team that was sponsored by her father. One of the racers, Geneviève Gambillon, told me, “Lyli was a tough master.” Lyli confirmed: “I told them, ‘Training for me starts at 5 o’clock in the morning, because I have to go to the shop afterward.'” When Gambillon complained about the hard workouts, Lyli told her, “I am 18 years older than you, and I am riding with you, not following in a car behind. If I can do it, so can you!” Lyli’s methods were questioned by some in the French Cycling Federation, but they brought results: Gambillon won two world championships and more than 20 French championships on road and track.

All her adult life, Lyli worked in her father’s shop, shown above in 1962 with Lyli’s first five French championship victories proudly listed on the window. As a teenager, she rode across Paris to pick up parts from distributors. Then she learned to build wheels, and from then on, she was responsible for this important part of the magical bikes her father created. She also ran the shop and distributed Velosolex mopeds on the side to augment the meagre bike sales during the difficult years of the 1960s, when most French dreamed of a car, and not a custom bicycle.

When her father died in 1976, followed a few years later by her mother, she took over. She married Herse’s master framebuilder, Jean Desbois, and together they kept the shop running until 1986. When the word spread that Cycles René Herse was closing, many customers placed orders for one more bike. Lyli and her husband worked for two more years out of the garage of their house until all the orders were filled, and they finally could retire.

I first met Lyli after riding a 1946 René Herse tandem in the 2003 Paris-Brest-Paris. She was delighted that we had continued the legacy she had worked so hard to build. As I visited her many times during the research for my book on her father and his bikes, we became friends, and she asked me to carry the René Herse name forward. I learned a lot from her and her late husband about the machines her father built. We organized annual reunions with the old riders of her father’s team, who also had much information to share.

Five years ago, to celebrate her 85th birthday, she asked to ride one more lap of the Poly. We found a René Herse tandem, and I had the honor to pilot her around the course together with a number of riders from her father’s team. I was apprehensive about climbing the famous 14% hill on a tandem with an 85-year-old lady, but Lyli had trained by riding thousands of kilometers on her stationary bike. On the climb, we dropped all the others, except my friend Christophe, who had been an strong amateur racer. And even he had to work hard to keep up. The slack upper connecting chain in the photo above says it all: Lyli was contributing more than her share of the power. 14% climbs have rarely felt so easy, and I suddenly could almost imagine how, 55 years earlier, she had ridden eight laps of this difficult course at an average speed of 35 km/h (22 mph).

Lyli continued to train every day, and she kept a log of every ride. When I called her on the phone, she often was out of breath: “Excuse me – I was training,” she explained. Always the champion, she wasn’t slowing down even as she approached the age of 90.

I had hoped to go for another tandem ride with her during my next visit – above a ride we took on our René Herse tandem two summers ago. Now Lyli is gone, but she’ll continue to inspire us!

Posted in books, People who inspired us, Rides | 24 Comments

12 Myths in Cycling (1): Wider Tires Are Slower

When we started to publish Bicycle Quarterly 15 years ago, it seemed that most of the technical aspects of bicycles were well-established. And yet, as we tested many different bikes, we started to question many of the things we had accepted as ‘facts.’ To celebrate our 15th anniversary, we’ll look at some of these myths. We’ll explain why we (and everybody else) used to believe them, and how things really work. Let’s start this series with the biggest one:

Myth 1: Wider Tires Are Slower

For almost a century, cyclists ‘knew’ that narrower tires roll faster. Some people realized that in theory, wider tires are faster due to their shorter contact patch, which deforms less as they roll. But the thinking was that in practice, the lower pressure at which wider tires must run limited their performance. If you wanted to go fast, you chose narrow tires.

That is what we thought when we started testing tires almost 12 years ago. And yet, as long-distance riders, we wondered whether the narrowest tires, pumped to the highest pressures, really were optimal for us. What if wider tires were a few percent slower, but their greater comfort reduced our fatigue? Remaining fresh toward the end of a long ride would help us put out more power, so we might go faster in the end. What we needed to know was how much speed we would give up by going to wider tires.

Real-Road Testing

So we started by testing 20, 23 and 25 mm tires (same tire model). Imagine our surprise when the 20 mm were slowest, and the 25 mm fastest. This wasn’t what we expected! And yet, when we repeated our tests with a different methodology (power meter vs. roll-down), the results remained the same. There was no doubt that the narrowest tires are slower than slightly wider ones.

Then we tested wider tires, and realized that, once you go wider than 25 mm, the performance of tires doesn’t change as they get wider. Since then, we’ve tried to figure out how wide a tire can be before its performance begins to drop off.

We’ve used the results of our testing to develop our Compass tires, which are optimized for performance and comfort on real roads. And since we now have very similar tires in widths from 26 to 54 mm, we could do controlled testing of all these sizes. We found that they all perform the same. Even on very smooth asphalt, you don’t lose anything by going to wider tires (at least up to 54 mm). And on rough roads, wider tires are definitely faster.

As we did more research, we realized that cyclists used to know this. When pneumatic tires were first invented, the fast-riding ‘scorchers’ used wide tires, because they rolled over road irregularities better. And in the 1920s, Vélocio, the editor of the French magazine Le Cycliste, discovered that as long as wide tires had supple casings, they rolled as fast as narrow ones. But all this was forgotten in later decades, as racers went to narrower and narrower tires.

Why did it take almost a century to rediscover this? There are two reasons why cyclists used to believe that narrower tires were faster:

1. Laboratory tests on steel drums eliminate the rider and thus the suspension losses. If you look at hysteretic losses alone, narrower tires run at higher pressures and thus flex less, meaning they absorb less energy.

We tested on real roads, with a rider on the bike, and found that the increased vibrations of the narrower tires caused energy losses that canceled out the gains from the reduced flex. These suspension losses are mostly absorbed in the rider’s body. Imagine a bean bag that drops on the ground without bouncing back – all the energy is absorbed by friction between the beans. The human body works similarly. Studies by the U.S. Army found that the more discomfort vibrations cause, the more energy is being absorbed.

2. Placebo effect: The faster we ride, the higher the frequency at which our bike vibrates, because our tires encounter road irregularities at a higher speed. However, narrower tires also increase the frequency of the vibrations they transmit. Basically, a bike with narrow tires feels faster even though it may actually be slower. Inflating your tires harder is a simple way of tricking your brain into feeling that you are going faster, but if you have a bike computer, it’ll tell you that you haven’t actually increased your speed. Conversely, wide tires vibrate less, and thus feel slow to most cyclists.

So for almost a century, narrow tires felt faster, and they tested faster in the laboratory. There was little reason to question whether they actually were faster. It took Bicycle Quarterly‘s real-road tests to show that a vibrating bike (and rider) is absorbing energy that reduces the bike’s speed.

What all this means is that you can have your cake and eat it, too. If you run wider tires at lower pressures, you increase the flex of the tire (negative), but you reduce the suspension losses (positive): the two effects cancel each other, and your speed remains the same.

This also explains why supple casings make such a huge difference in tire performance: They are easier to flex, so they absorb less energy. And they absorb vibrations better, which reduces the suspension losses. So they use less energy on both counts. Talk about a win-win scenario! And of course, since they absorb vibrations better, they are more comfortable, too.


What about the aerodynamics of wider tires? Many riders believe that wider tires will be slower, because they have more wind resistance. We tested this in the wind tunnel and found that the difference between 25 and 32 mm tires was too small to measure reliably in a real-world scenario. The German magazine TOUR built a sophisticated setup with a motorized dummy rider and found that a 28 mm-wide tire had the same wind resistance as a 25 mm tire when the wind was coming from straight ahead. With a crosswind, the wider tire was very slightly less aerodynamic. Even then, the wider tires required only 5 watt more – on real roads, the reduced suspension losses probably make up for that.

We tested our tires on smooth pavement at 29.5 km/h (18.3 mph), and found no speed difference between narrow and wide tires. If you ride much faster, then it’s possible that wider tires roll a little slower, but the difference will be so small that it’ll get lost in all the other factors that influence your bike’s speed. On the other hand, if you ride slower, then the advantage of wider tires will be even greater.

Spinning up

Wider tires are a little heavier than narrow ones. The difference is smaller than many cyclists imagine – air doesn’t weigh anything – but a wide tire has a little more rubber and casing. Won’t this make the wider tires harder to accelerate? The answer is “No.” The reason is simple: Bicycles don’t accelerate very quickly. Even a professional bike racer’s power-to-weight ratio is far less than that of the slowest economy cars, and those don’t exactly push you back in the seat when you floor the throttle. Bikes don’t accelerate fast enough for small changes in wheel weight to make a difference. That is why professional sprinters can use relatively large wheels (which inherently are heavier) and still win races.

The UCI requires a minimum wheel size of 55 cm, yet racers use 700C wheels that are 10 cm larger than required. If wheel weight mattered as much as most cyclists imagine, then pros using the smallest wheels would win every race. And yet, even though many have tried smaller wheels, all have returned to 700C wheels – probably because the larger wheels handle better due to their optimized rotational inertia. (But that is a topic for another post.)


What this means for us riders is that we can choose our tire width freely, without having to worry about performance. Of course, this doesn’t mean that a wide ‘touring’ tire will perform as well as a narrow ‘racing’ tire. Casing performance determines 95% of a road tire’s speed, and to get good performance, you need a supple high-performance casing. (The other 5% come from the thickness of the tread.)

Tire width influences the feel of the bike, but not its speed. If you like the buzzy, connected-to-the-road feel of a racing bike, choose narrower tires. If you want superior cornering grip and the ability to go fast even when the roads get rough, choose wider tires.

Further reading:

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