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.

Aerodynamics

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.)

Conclusion

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:

About Jan Heine, Editor, Bicycle Quarterly

Spirited rides that zig-zag across mountain ranges. Bicycle Quarterly magazine and its sister company, Compass Cycles, that turns our research into the high-performance components we need for our adventures.
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53 Responses to 12 Myths in Cycling (1): Wider Tires Are Slower

  1. Eli says:

    Please excuse the tangential question, but what bar tape is pictured at the top of this post?

  2. Nelson Zornitta says:

    Hi, Jan

    Can you tell me the total diameter of a Switchback Hill?
    I´ll use a rim with 21 or 25mm internal (if that change anything) and I have clearance for a tire until 690mm.

    Thanks,

    • That will be a tight fit. Depending on the rim, on the casing (Extralights tend to be wider) and whether you mount it tubeless (which also makes the tire ‘grow’ a bit), the Switchback Hill 650B x 48 mm will be about 691 mm in diameter, give or take 2-3 mm… The Babyshoe Pass should fit fine, of course, as it’s about 12 mm smaller in diameter.

  3. Michael Martinov says:

    I compared wide and narrow tires, 42 and 32 mm Clement X’plor MSO, on my cyclocross bike and found one drawback with wide tires – the handling of the bike is worse, I think because contact patch of the front tire is almost square on the wide tires and more elongated in narrower tires. This is especially evident in mud, rough surface, and for a light cyclist (60 kg).

    • You are right – wider tires change the handling of the bike because the wider tires stabilize the bike – this works a bit like the geometric trail of the front-end geometry, and thus it’s called pneumatic trail. The ideal bike for wide tires has a front-end geometry that is designed for the wider tires, usually by reducing the geometric trail. Then, a bike with wide tires can handle the same as a bike with narrower tires. We’ll cover that in another part of this series about ’12 Myths of Cycling.’

  4. peterthelibrarian says:

    Do you have any knowledge or predictions about how this applies to fat-bike tires?

    • At some point, tire performance must get worse as tires get wider. In our testing, we’ve only gone to 54 mm – we need tires that have the same casing, same tread pattern, same tread rubber and thickness, etc., but come in different widths. Our Compass tires meet these criteria, but they come only in widths up to 54 mm, so that is the widest we’ve tested. We can say that 54 mm tires aren’t slower than 25 mm tires, but what happens beyond that – nobody knows!

      For tire performance, the casing construction is more important than all other factors. I don’t know of any fat-bike tires that have a high-performance casing, so at least for now, we can say that fat-bike tires will be slower – if not due to their width, then due to their construction.

      • Andy Stow says:

        My long-term average speed on my Surly Pugsley, with knobby 3.8″ (96 mm) tires is 10 MPH. On my steel touring bike with 38 mm and 32 mm Compass tires, it’s 12 MPH. Part of the difference is that I mostly ride the Pugsley in the winter, including in snow, so they’re actually closer than those numbers imply.

        Right now I’m struggling with tire rolling resistance in the cold. I’ve been riding in -14 °F to +10 °F temperatures, and the air density is obviously part of it, but I feel like I’m riding on molasses. I averaged about 7 MPH on a recent ride, which would be fine if it was due to snow, but even on the cleared road sections I could only cruise at 9 MPH on the fatbike, where I know I’ve done 12-14 MPH in the summer with the same bike and tires.

      • The rolling resistance of tires increases significantly with cold temperatures. The reason appears to be that the rubber gets stiffer when it’s cold. For the same reason, tires have less grip in cold weather.

        We haven’t tested this, but it stands to reason that sturdy tires with more rubber suffer more from this effect than tires with supple, thin casings. Of course, one other factor may be the human body performing best at a certain temperature. And then there is the added clothing that constricts your movements.

  5. wayne says:

    What width have you found to be the sweet spot for a tire from a ‘fastest tire there is’ perspective? All I hear is wider is faster, but when does a wider tire actually become slower? At some point tires have diminishing returns based on how wide they are, otherwise we would be all racing on fat bike tires on the road.

    I get there are a lot of variables at play here such as aerodynamics, casing, tread, weight, etc so lets use the bon jon tread/ casing as an example. What would be the fastest width of this tire all the way from 19mm to 50+ mm, what is the fastest width given all the variables?

    cheers.

    • Good question! What we know is that up to 25 mm, tires get faster as they get wider. So 19 mm is probably the slowest you can ride. Beyond 25 mm, you reach a big plateau, where tire performance doesn’t change – at least on smooth paved roads and at moderately high speeds. We don’t yet know where the plateau ends – 54 mm tires are as fast as 25 mm tires. On rough roads, they are faster, on a super-smooth wooden track, they may be a bit slower…

      For pro racers, it makes sense to use 25 mm tires for most races. The roads are smooth, they are lightweight, and they use tubulars anyhow. A wider tires won’t be much slower, but it’ll be a little heavier, and even if the difference is mostly psychologic, it can make a difference. And if you lose 5 seconds up the 20-minute climb a big mountain pass, that can make the difference between getting dropped or staying with the bunch. For the rest of us, those five seconds aren’t that important compared to improved comfort and better grip, plus the ability to go on rough roads. Even races sometimes go over rougher roads, so it’ll be interesting to see how the pro’s tire choice evolves. I wouldn’t be surprised if they soon would ride 28 or even 30 mm tires, especially if their sponsors are starting to push wider tires on road bikes.

      For the cobblestone races like Paris-Roubaix, they already are using much wider tires. There, it seems that the pros are limited by the bikes and tires they can get. Wider certainly makes sense there: Global Cycling Network tested a mountain bike against a cross bike and a racing bike on a sector of pavés, and found that the mountain bike was fastest, despite the rider not being able to put out as much power – all due to the wider tires. Now imagine if the rider had put out their max power on a frame with better performance and had been riding supple tires designed for speed – the difference would have been even greater.

      • wayne says:

        thanks for the reply.

        When you say a 25mm tire is as fast as a 54mm tire, are you talking on average paved flat roads?

        Others comments got me thinking more, now Im curious what the ‘fastest’ width tire would be for like a 40 mile ride with average (2000ft ) of climbing would be. I for one can definitely notice when im climbing with my racing wheels and racing tires vs heavier wheels and tires, but I don’t think the weight difference between a 25mm and 54mm tire would be inconsequential.

      • We tested on very smooth asphalt – the apron of an outdoor velodrome. As to the actual on-the-road speed of your bike, there are many factors – see also the previous comment about climbing speed. When I raced, my race wheels used superlight rims, extra-thin spokes and were shod with cotton tubulars. On my training wheels, I had stiff, kevlar-belted tires. Of course, the racing wheels were much faster, but it wasn’t because the tires were 6 mm narrower!

        Regarding tire weight, consider that you need a smaller wheel with the wider tire to keep the handling the same (and to fit it into a frame). A 700C Compass Cayuse Pass Extralight 26 mm tire weighs 183 g, a 26″ Rat Trap Pass Extralight in 54 mm width comes in at 418 g. Even for two tires, that difference is only 470 g, or half a water bottle. Deduct the smaller, lighter rims and shorter spokes, and the difference is even smaller.

  6. Rick Harker says:

    I often hear the big negative tire/speed/aero comments when riders look at my wheels but lately I ask if they have documented evidence to support their claim.

    • Ian says:

      Don’t underestimate the persuasion of anecdotal evidence- the best argument you could make would be dropping them. And the worst argument would be getting dropped, evidence be damned.
      When it comes to speed, engine size matters a lot more than tire size.

  7. Mike C says:

    I’m a firm believer in your approach to dispel these myths and appreciate the time and effort that you have taken to do this in a careful empirical manner. You often pose the question of why it has taken so long for the cycling community to realize that wider is not slower. I get that. But, I have not seen a good explanation as to why cyclists started riding narrower pneumatic tires in the first place. Are there reasons beyond the perception that the narrower tires are faster based on feel?

    • It’s hard to know why riders started to ride narrower tires as soon as the memories of the ‘boneshakers’ with their solid or hollow (but airless) rubber faded from memory. We know that already in the 1920s, the young riders from Paris who came to southern France to meet the mythical Vélocio rode what they called ‘pencil tires.’ They were surprised how fast the wide, supple tires of the ‘master’ rolled…

      That doesn’t answer why riders believed that narrower tires are faster. I suspect it was indeed the placebo effect of the increased vibrations.

  8. Lawrie Cranley says:

    Thanks for your informative article. I realise your article is about tyre width specifically but don’t you think TPI (threads per inch) is also very important in handling and speed of a tyre. The suppleness of the casing has to have a big role to play in this. It would be interesting to see an article that covered both topics and either prove or dispel the idea of the higher the TPI, the better the tyre. I think it would probably prove a big bag tyre with high TPI is the best.

  9. larryatcycleitalia says:

    As usual, thanks for pointing this out. As an old moto guy I guess I “knew” this based on the motorsports experience, especially with two-wheels. More rubber on the road is better than less while less pressure is better than more. And with bicycles, the tires are pretty much the only suspension one has. Every motor sport that races on rubber tires uses the biggest ones the rules allow and puts in as little air pressure as they can get away with.
    Getting bicycle riders to accept this concept was like yelling into a hurricane for years, but thanks to you and Josh of Zipp/Silca it’s finally being accepted.
    Looking forward to the other 11 myths being destroyed.

  10. Adam Heintz says:

    Perhaps I have misunderstood your statement, but “– air doesn’t weigh anything –” is incorrect. Air has mass. I’ve long forgotten the gas equations, but a skinny high pressure tire and a fat low pressure tire may have the same mass of air within, but that air absolutely has mass. A tire with 125 psi will weigh more than when it has 30 psi. I doubt that the actual difference is much of a factor, but there is a difference.

    • Joe Wein says:

      Yes, air does have mass, but it is pretty negligible. Air at room temperature and sea level pressure weighs about 1 g per liter. A 650B tire at 42 mm width inflated to 3 bar holds about 8 liters of air more than it displaces. A 700C tire at 25 mm width inflated to 6 bar holds about 6 liters of air (6 g). The weight of air is negligible compared to the weight of the rubber that encloses it or the weight of steel and aluminium that supports it, let alone the weight of the engine.

      • Grant says:

        Calculating the mass of the air via formulas would be the gold-standard, but I have a practical way of measuring it. My road bike is “about right” after taking a 12g cartridge of co2, and my mountain bike takes a 16g cartridge. co2 weighs 1.52 times as much as air, so that correlates to air weights of 7.9 and 10.5 grams.

  11. Mark says:

    I not so sure it is a myth, as MIT university did studies on bike science quite a while ago. As with most things in cycling, the products sold are also driven by marketing forces with pseudo science to back it up. If you look at tires from the first Tour de France to today, the tires in the 1900s are narrow compared to mtb width tires today. Roads were worse back then too. From what I can see, you can see tires getting narrower in the 1930’s. Probably Michelin or some other tire company decided to make tires narrower to conserve resources or to make more money per tire sale. In the 40’s and 50’s you can see tires getting narrower. I doubt it was just because people thought narrow was faster. Narrower is lighter for racing in hills but you also can make more tires with given material quantity. Bikes frames were also getting better, and designed to fit narrow tires, so once you had a bike that can’t fit wide tires, you are stuck with narrow tires. Basically, a lot more going on than a myth or belief.

  12. Mitch Harris says:

    Can you say anything else about climbing, long slow climbing on wider tires? That’s the challenge I frequently hear about wider tires in my riding area with long canyon climbs. Your points about weight and spinning up certainly apply. Since overall bike weight affects climbing speed, the small extra weight of a wider tire will cost a little speed. However, the slow climbing speed means any small aero loss is that much less important, and any rolling resistance advantage of wide tires is that much more important. Once you’re descending the canyon there’s another speed advantage of a wider tire, but I’m curious about how to explain the wider tire’s affect on the long slow climb. Thanks

    • If you look at simple physics, then it shouldn’t matter. The weight difference is too small to be noticeable – nobody ever said they got dropped on a climb because their water bottle was half-full, while the next rider had an empty bottle.

      But bikes aren’t simple. If you climb out of the saddle, then you rock the bike from side to side, and there, the weight and rotational inertia suddenly become important. As an extreme example, the Rawland Ulv we tested in the current Bicycle Quarterly with its 80 mm-wide tires was almost impossible to rock from side to side while climbing out of the saddle. Going to a smaller wheel can compensate for the larger, heavier tire: My Firefly with its 54 mm-wide 26″ wheels feels very similar to a racing bike with 700C x 25 mm tires.

      Then you have issues such as ‘planing,’ where frame flex can either be beneficial or detrimental. Some people have talked about ‘micro-accelerations’ that make lighter wheels climb better – perhaps especially with stiff frames that don’t have much give to smooth out the rider’s power stroke. On the other hand, at the right pressure, a wide tire also can provide the flex that we like in the best high-performance frames – the Open U.P. with its very stiff frame climbed better for me with the tires at ‘gravel’ pressure than at the higher ‘road’ pressure. So it’s a complex issue, and isolating the tires is difficult, as they are always part of the system of the entire bike and the rider. It’s conceivable that your bike will climb slightly slower (or faster) if you go to wider tires.

      That said, when everything is optimized, there is no reason why a bike with wider tires should climb slower. We’ve put my Firefly through our back-to-back hillclimb tests, and its performance matches that of the best bikes we’ve tested.

      • Mitch Harris says:

        Thanks. Matches my own impression– I can’t find any evidence that wider tires climb slower (comparing Compass EL to Compass EL). Like you say, other aspects of the bike do seem to make noticeable differences in climbing.

  13. Mark says:

    After doing research on just Schwinn, its obvious narrow tires are a product of marketing and reducing weight. Schwinn marketed all skinny tire bikes as racers and as light bikes. Even though some weighed over 40 pounds. Obviously the frame material and parts weight of racer bikes versus balloon tire bikes was similar. So to make bike lighter, narrow wheels and tires was an important key. Compared to a balloon tire bike, any skinny tire would be faster. So not really a myth, but just the way it was when bikes were made of heavy material. Would be true of bikes made in Europe too except for different wheel sizes.

  14. Dr J says:

    Myth #1 is not a myth… on velodrome. The track is smooth, suspension losses are negligible so wide tires aren’t needed. Also, aerodynamics matters a lot, lot more, which is why narrower tires are better.
    But obviously, most of us don’t ride bikes on velodromes.

    • No flats on a velodrome, either, which is another reason to ride wider tires (fewer flats).

      However, even on a velodrome, suspension losses may be greater than we used to think – witness many pro track riders going to slightly wider tires and lower pressures. Testing tire performance on an indoor track is easy in the age of power meters – no wind, constant temperature, etc. – so unlike on the road, the ‘perfect’ tire width shouldn’t take long to establish.

    • Mitch Harris says:

      Suspension losses are evident on velodromes too. The typical outdoor velodromes people usually ride have rough areas, poor joints, or are generally rough surfaced, sometimes more rough than a typical smoothly paved road. Even high quality indoor wood tracks age and get rough enough to notice, like the old Ghent track that had lots of boards you feel and areas you avoid lap after lap if you can. Many indoor wood tracks have rough joints you feel four times a lap–wump wump, pause wump wump, every lap. This is a regular part of racer conversation at a velodrome, how the surface is, where the rougher and less rough parts are. On every track where I’ve raced I was aware of how much better and faster a good supple tubular (eg Vittoria CX) feels compared to a cheaper vulcanized tub. If you can feel that difference, then there are suspension losses you’re coping with (absorbing physically).
      Your comment is true I think if you’re talking about a surface without suspension losses but real world Velodromes aren’t that.

  15. Thanks, this is interesting, and it takes a while to understand what the results mean in practice.

    When you say that performance was constant between 25–54mm, what is the measurement error at that interval? Performance is constant plus minus how many percent?

    Better yet, would it be possible to have the raw data for reanalysis? 🙂

    Do you think the result generalizes well to other kind of tires that are identical except for the width, whatever that means, or are there certain kind of tires where things would likely be different?

    And last one that comes to my mind, what about say 2”–4” tires on mountain bikes. I guess it depends on the terrain and everything…

    • For the actual data, please check the back issues of Bicycle Quarterly. It’s too much for a simple blog post.

      As to the measurement error, there is some noise in the data. You also have to remember that while we use tires that in theory use the same casing, tread thickness, etc. in the various widths, in practice, they are different tires. And with all tires, there are variations in rubber coating of the sidewalls, etc. To get around that problem, we tested lots of tires. If the wider ones were slower, we’d expect to see a general trend in our data. As it was, the 32 and 51 mm tires actually were fastest, while the 38 and 52 mm tires were slowest.

      We rode on very smooth asphalt for this test. We’ve tested on rougher surfaces in the past, and there, wider tires are significantly faster. The biggest issue is making a high-performance frame that fits the widest tires – I think that limits performance more than the tire itself.

  16. 2 Wheeled Wanderer says:

    Overall excellent article, and I myself prefer wider tires (32mm). I do question a statement in the last section. Specifically, “Won’t this make the wider tires harder to accelerate? The answer is ‘No.’ The reason is simple: Bicycles don’t accelerate very quickly.” On the face of it, this is a true statement. But it doesn’t tell the whole story, namely, of the effect of the greater rotational weight during the frequent climbs that are part and parcel of road riding. While it is true that the small weight difference felt a single acceleration would be negligible, only the absolute smoothest of pedalers don’t actually accelerate (and decelerate) slightly with every stroke when going uphill. Thus, every climb is a long series of small accelerations, resulting in what I believe would be a more significant cumulative effect of the otherwise insignificant weight difference felt in a single acceleration. (I.e., All other things being equal, I think wider tires do actually CLIMB more slowly.)

    • Mitch Harris says:

      Lighter wheels/tires decelerate faster too.

    • Sam Atkinson says:

      >”Thus, every climb is a long series of small accelerations, resulting in what I believe would be a more significant cumulative effect of the otherwise insignificant weight difference felt in a single acceleration.”

      Inertia works both ways. A wheel with a heavier rim is slower to accelerate uphill, but also decelerates slower.

      My guess is that climbing performance loss from heavier wheels would have to come primarily from the simple increase to gravitational drag, and effects on the rider’s form.

      • You’d expect a heavier wheel to smooth out the rider’s power stroke, but reality seems to be more complex – nobody ever claims to have climbed better on heavier wheels! It might be a fun subject to test: Add invisible weights to one set of test wheels but not to the other (identical one), and then ride both wheels up a hill, measuring power and speed. Equalize the bike weight using water bottles filled with weight for the lighter wheels, empty bottles for the heavier wheels. Keep the test double-blind and use several testers… Similar to our tests of frame stiffness, but actually less involved – no need to build four identical frames and get identical parts kits to build them up. We’ve been talking about this one for a while now…

    • Mark says:

      Another aspect to consider is the wheel diameter. A 32mm tire will give a wheel a larger diameter than a 20mm tire. This will affect performance perception and ride quality. I have a bike with 28c wide tires, and it sure does feel different than my 23c tires since they are noir the same tire brand, its hard to say what the difference is though. But in theory, a larger diameter wheel due to wider tire will make the bike ride differently. Generally the larger tired wheel will accelerate slower, but will maintain a higher speed at the same power output. Climbing would feel different to. I have a folding bike with 20 x 1.5 tires and it accelerates real easily, and climbs really well. It feels fast, but because the wheel size is smaller, the speed per power output is slower. It is harder to maintain the same speed as someone on a 700c wheeled bike. So tire performance is also affected by the fact that wider tires are also taller tires.

      • The difference in wheel diameter due to larger tires is relatively small. The only thing it changes is the gearing. The same gear rolls further with wider tires, making it harder to pedal, which may contribute to the perception that wider tires are slower…

  17. 2 Wheeled Wanderer says:

    Sorry. Just read the request for real names. Mine is Chuck.

    • Thank you for adding your name – it helps to keep the conversation civil. As to your comment above:

      The ‘micro-acceleration’ argument is interesting. However, the same logic applies as to sprinting: If lighter wheels climbed much faster, all pro racers would use the smallest wheels allowed by the rules – currently 55 cm outer diameter. Yet Froome and Co. all ride 700C wheels that are 10 cm larger than required…

      As I mentioned in an earlier comment, I think the situation is more complex: When you climb out of the saddle, the lateral acceleration of the bike is actually quite large – at 90 rpm, the bike has to go from zero to maximum and back to zero three times every second! I am sure that in that scenario, wheel weight matters a lot. However, the fact that pros all chose the same (larger than necessary) wheel size indicates that there may be an optimal rotational inertia. After all, you rock the bike to get more power, and you need something to push against. If the bike rocks too easily, it may not perform well, and if it is too hard to move, it’s also not optimal…

      To keep the rotational inertia constant with wider tires, you go to smaller wheels. I’ve mentioned my Firefly before – with 54 mm tires on 26″ wheels, it feels the same as a racing bike with 28s…

  18. Tim Nielsen says:

    The professional preference for 700c wheels might well be related to the logistics of running different sized wheels, it would seem prohibitive. Luckily, we are not bound by such factors!
    Additionally, Some of the bigger climbs encountered in racing are immediately followed by descents. Is it a question of familiarity? A transition from a special climbing bike to a dangerous downhill on unfamiliar equipment could spell disaster.

    • Quite a few pros tried smaller wheels. In one of our calendars, we featured a lovely 1982 Colnago built for Guiseppe Saronni, who won the world championships that year, with 650C wheels. The thinking probably was that as a sprinter, Saronni would benefit from the smaller and lighter wheels. He raced an almost identical bike, but with 700C wheels, instead – and won. Clearly, the smaller wheels didn’t offer a worth-while advantage – as a high-level racer in a field of similar strength, you know that you win only if all the stars align. If you can get a 5% advantage due to smaller wheels, you’ll take the risk that your race is over if you have a flat and can’t get a wheel in your size. If you flat in every 10th race, but win half of the other 9 due to the better-accelerating wheels, you are way ahead of the odds!

      As to climbing and descending, David Levy of Ti Cycles used to race a 650C bike in the hilly road races of the Pacific Northwest. I raced against him many times. The smaller wheels seem to have caused few problems on the descents – I don’t remember him crashing more than anybody else. In fact, I don’t remember him crashing at all…

  19. Piaw Na says:

    I think the “myth” is mostly due to the difficulty (and expense) of finding high quality wide tires. I can certainly believe that the Michelin Pro 4 28mm isn’t (much) slower than the Michelin Pro 4 25mm. But the 28mm tire is not the same as say, the 25mm Pro 4 Race tire because it’s got a thicker thread. The wide tires referred to on this post cost north of $50 each, while I can get my 25mm Michelins for $30 or so (sometimes in a bundle that includes inner tubes!). If you’re spending the same $30 on say, Panaracer Pasela 32s, there’s no way you’re going to get similar performance to the 25mm Michelins.

    • You make a good point – wide tires with excellent performance are few and far between. We introduced our Compass tires because existing tires didn’t offer the performance, comfort and grip that we knew was possible from our testing. As you point out, even today, most tire makers don’t offer their wider tires with the same specs as their high-performance racing tires.

      Regarding cost, the cost-per-mile of wide tires actually is far lower than that of narrow ones, because wide tires wear so much slower. When I rode and raced on 20 mm tires, it was rare to get 1000 miles out of a set of tires. Now, with my 42s, 5000 miles is normal, and often, they last even longer. That means at the same initial cost, the wider tires are five times cheaper per mile – putting the best Compass Extralights on par with budget narrow tires that offer poor performance, a harsh ride and will puncture far more frequently.

  20. Fraser says:

    Thanks for the interesting article. I’ve been riding wider tires (28c) on my road bike for years now because of some of your testing, and have enjoyed the comfort advantage. I’ve recently purchased a Hook EXT_C which will take up to 2.1″ 650b tires. I’m dreaming of (and dreading) riding this bike from Tuktoyaktuk to Whitehorse this spring. It’s half gravel road (with a reputation for wrecking car tires) and half rough paved road, about 1400 km in total. Would you recommend a set of your tires for the trip? or do you think I’d be better going with a stiff touring tires to avoid flats, sidewall tears etc. Cheers,

    As a Post Script Andy Stow asked above about fat bike tires and his feeling of “riding on molasses”. While fat tires are heavy and stiff, Cardiovascular and metabolic inefficiencies are an important consideration for riding in cold weather. Your body is simply not as efficient of producing watts at cold temperatures.

  21. David Bump says:

    I’ve settled on 25mm for my commute into downtown Denver, which has some amazingly rough pavement. One issue I face is pinch flats on rough spots if my tire pressure is lower than 80psi or so (in 20 years of commuting, I’ve bent 3 rims irreparably on road “imperfections”–I love Denver, but our pavement sucks). In theory, a wider tire at a lower pressure will survive the same sharp jolt as a narrower/higher pressure tire, but I wonder if the pressure required, even on a wider tire, narrows the overall performance gap between the two? That’s a much more excruciating scenario to test, I realize. In ideal circumstances and lighting, avoiding those sharp jolts is the best option, but in practice, that’s not always an option.

    • I think you’ll find that a wider tire not only won’t get pinch flats, but it’ll also roll over those jolts much better. For urban riding, wide tires really are a win-win-win scenario: Same or better performance, more comfort and fewer flats. Add a fourth ‘win’: lower cost, because you get more miles out of them.

      I commute on 42 mm tires. I sometimes ride a test bike with narrower tires in the city, but I always wish for wider ones…

    • Jacob Musha says:

      There’s no situation where I want to ride any tire as narrow as 25mm, especially not commuting. Wide tires are just as fast and the reduced mental (and physical) effort spent on avoiding bumps is such a relief. I’ve been commuting on 38mm and 53mm Compass tires this year. The 53s are probably overkill (I only weigh 140lbs) but they’re my favorite. Cracks, potholes, railroad tracks… All can be almost completely ignored. I don’t even bother to un-weight the bike most of the time. Off-road excursions are always an option.

      If you’re getting pinch flats and bending rims that’s a sure sign your tires are way too narrow. Give wider tires a try. As long as you choose high performance ones, you’ll never go back.

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