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I’ve ridden 25mm to 32mm tyres on the same bike, in the same season, and my (absolutely amateur, I’m 250lb and did 125 miles at 16mph) experience is that 32mm t

I’ve ridden 25mm to 32mm tyres on the same bike, in the same season, and my (absolutely amateur, I’m 250lb and did 125 miles at 16mph) experience is that 32mm tyres are no slower, but are significantly more comfortable, and allow me to ride significantly longer with less fatigue. Does anyone else have any other data points?

haswell 5y ago
I've spent a lot of time with 28mm tires, but I'm absolutely in love with my 38mm GravelKing slicks. I don't really notice much speed difference (if any), and the comfort level makes up for it if there is. I ride for fitness, so I'm happy. More details in my other comment (I actually ride a gravel bike so I have the extra clearance for big fat tires if I need).
- kazinator 5y ago
  The comfort level you feel is also a form of efficiency that makes you faster. Vibration absorbs energy and saps your momentum.
twoWhlsGud 5y ago
This is all anecdotal, but a couple of decades ago I was riding road bikes with standard 622 rims shod with 23 mm tires. In the 2000s I shifted to riding road bikes with 584 rims and 42mm tires because they were frankly just more fun for me (lower pressure = greater comfort and better suspension meant better handling on our rough Northwest roads). The outer diameter was about the same, so I didn’t have to do something weird with the geometry of the bikes. When Jan came out with 55mm super-supple tires on 559 rims (again that would keep the outer diameter the same) I thought what the heck and got Seven Cycles to build me a custom around the new tires. Now that road bikes run disk brakes, you can run multiple rim size on the same frame so I figured I could always go back to 584/42mm if I didn’t like the crazy wide tires. (I was worried enough that I actually got somebody to build me a new set of 584 rims for the new frame.) I’ve had that bike for about 3 years now and have ridden several thousand miles on it. Only a few tens of those miles have been on the fancy 584 rims with the (equally nice) 42mm tires – the 55mm tires are even more fun than the 42's were for me. If you ride on mixed surfaces, the extra suspension you get from running low pressures (I run around 26 PSI front/32 back) makes a big difference (or at least it does for me) - both in handling and comfort. Downsides are increased weight (the 55mm tires weigh about 420 g a piece which is impressively light given the amount of material, but still a lot heavier than those old 622/23 mm tires back in the day) and the increased maintenance of running them tubeless (though of course you can run them with tubes-though given that I haven’t had a flat in 3 years and I’m riding on Seattle streets, I’ll put up with having to monitor the sealant levels every month or so).
- kazinator 5y ago
  I suspect that 42mm is already into diminishing returns for road cycling.
  - carl_dr 5y ago
    I am definitely slower - 4.5mph or so - on my 42mm gravel bike on road than I am on my 32mm road bike. But my road bike has slick tyres and the gravel bike’s tyres are more knobbly, and I run the gravel bike’s tyres at much lower pressure. (And there is the difference in geometry of each bike, too.) I’m not even sure you can buy 42mm slick tyres, so a like-for-like comparison is probably very hard.
    - kazinator 5y ago
      Slick tires, by which I mean minimal treat pattern, do exist in 42mm or even wider widths. (Source: I have seen them on bicycles.)
    - wiredfool 5y ago
      Rene Hearse sells tires from 26 mm to 55 mm all with the same tread and casings. That’s part of why they can do this test with some level of accuracy.
    - deleted 5y ago
      [deleted]
wiredfool 5y ago
Yes. I swapped RH tires onto my road tandem, 26x44 on the front and 26x54 on the back (from schwable 40mms), and the average ride speed I saw went from the 16mph range to the 17mph range, and the first time out on the new tires we increased our fastest average ride ever speed from 17.25 to 18.25 mph. And, the stoker is happier because the ride is that much better.
matsemann 5y ago
Lots of the wattage gains in tests are often only noticeable when the speed approaches 40km/h. Wonder about the effect at pro levels, if 32mm is viable there. My longest is 300km with 35km/h avg (185 miles, ~22mph) running 25mm. No problems with comfort. Never tested other wheels on this bike. But I do have a gravel in same price range with wider tires. That I can follow easily in a group, but alone my speed is slower for the same wattage. Might be the more upright position though.
- PaulDavisThe1st 5y ago
  This is a misconception, I think, although your experience seems like enough that I'm surprised you'd make it. The "big" changes that happen as you approach and go beyond 40km/h are due to (aerodynamic) drag coefficient, which has very, very little to do with the width of your tires. The changes that Heine is talking about are not related to drag coefficient at all. Worth noting that Heine himself is a legendary ultra-cyclist. He holds the record on the Cannonball (Seattle to Spokane on I-90, 300 miles) in the self-supported category. He would routinely other riders (e.g. me) even though he had to pull off the interstate to restock on fluids and food.
  - matsemann 5y ago
    > This is a misconception, I think My comment was more general, as in that lots of truths and myths about bicycling stems from people talking about different speeds. So stuff like "x doesn't matter" some amateurs say, but that x actually starts to matter when the speed increases. Or the opposite, lots of marketing about how product y saves z watts making us amateurs buy it, but then that test was on a already perfect setup at high speeds we're never gonna reach. But given most data is pointing to wider being better (or, not less effective but more comfortable) I'm wondering why pros aren't running wider.

haswell 5y ago

I've spent a lot of time with 28mm tires, but I'm absolutely in love with my 38mm GravelKing slicks. I don't really notice much speed difference (if any), and the comfort level makes up for it if there is. I ride for fitness, so I'm happy. More details in my other comment (I actually ride a gravel bike so I have the extra clearance for big fat tires if I need).

kazinator 5y ago
The comfort level you feel is also a form of efficiency that makes you faster. Vibration absorbs energy and saps your momentum.

twoWhlsGud 5y ago

This is all anecdotal, but a couple of decades ago I was riding road bikes with standard 622 rims shod with 23 mm tires. In the 2000s I shifted to riding road bikes with 584 rims and 42mm tires because they were frankly just more fun for me (lower pressure = greater comfort and better suspension meant better handling on our rough Northwest roads). The outer diameter was about the same, so I didn’t have to do something weird with the geometry of the bikes. When Jan came out with 55mm super-supple tires on 559 rims (again that would keep the outer diameter the same) I thought what the heck and got Seven Cycles to build me a custom around the new tires. Now that road bikes run disk brakes, you can run multiple rim size on the same frame so I figured I could always go back to 584/42mm if I didn’t like the crazy wide tires. (I was worried enough that I actually got somebody to build me a new set of 584 rims for the new frame.) I’ve had that bike for about 3 years now and have ridden several thousand miles on it. Only a few tens of those miles have been on the fancy 584 rims with the (equally nice) 42mm tires – the 55mm tires are even more fun than the 42's were for me. If you ride on mixed surfaces, the extra suspension you get from running low pressures (I run around 26 PSI front/32 back) makes a big difference (or at least it does for me) - both in handling and comfort. Downsides are increased weight (the 55mm tires weigh about 420 g a piece which is impressively light given the amount of material, but still a lot heavier than those old 622/23 mm tires back in the day) and the increased maintenance of running them tubeless (though of course you can run them with tubes-though given that I haven’t had a flat in 3 years and I’m riding on Seattle streets, I’ll put up with having to monitor the sealant levels every month or so).

kazinator 5y ago
I suspect that 42mm is already into diminishing returns for road cycling.
- carl_dr 5y ago
  I am definitely slower - 4.5mph or so - on my 42mm gravel bike on road than I am on my 32mm road bike. But my road bike has slick tyres and the gravel bike’s tyres are more knobbly, and I run the gravel bike’s tyres at much lower pressure. (And there is the difference in geometry of each bike, too.) I’m not even sure you can buy 42mm slick tyres, so a like-for-like comparison is probably very hard.
  - kazinator 5y ago
    Slick tires, by which I mean minimal treat pattern, do exist in 42mm or even wider widths. (Source: I have seen them on bicycles.)
  - wiredfool 5y ago
    Rene Hearse sells tires from 26 mm to 55 mm all with the same tread and casings. That’s part of why they can do this test with some level of accuracy.
  - deleted 5y ago
    [deleted]

wiredfool 5y ago

Yes. I swapped RH tires onto my road tandem, 26x44 on the front and 26x54 on the back (from schwable 40mms), and the average ride speed I saw went from the 16mph range to the 17mph range, and the first time out on the new tires we increased our fastest average ride ever speed from 17.25 to 18.25 mph. And, the stoker is happier because the ride is that much better.

matsemann 5y ago

Lots of the wattage gains in tests are often only noticeable when the speed approaches 40km/h. Wonder about the effect at pro levels, if 32mm is viable there. My longest is 300km with 35km/h avg (185 miles, ~22mph) running 25mm. No problems with comfort. Never tested other wheels on this bike. But I do have a gravel in same price range with wider tires. That I can follow easily in a group, but alone my speed is slower for the same wattage. Might be the more upright position though.

PaulDavisThe1st 5y ago
This is a misconception, I think, although your experience seems like enough that I'm surprised you'd make it. The "big" changes that happen as you approach and go beyond 40km/h are due to (aerodynamic) drag coefficient, which has very, very little to do with the width of your tires. The changes that Heine is talking about are not related to drag coefficient at all. Worth noting that Heine himself is a legendary ultra-cyclist. He holds the record on the Cannonball (Seattle to Spokane on I-90, 300 miles) in the self-supported category. He would routinely other riders (e.g. me) even though he had to pull off the interstate to restock on fluids and food.
- matsemann 5y ago
  > This is a misconception, I think My comment was more general, as in that lots of truths and myths about bicycling stems from people talking about different speeds. So stuff like "x doesn't matter" some amateurs say, but that x actually starts to matter when the speed increases. Or the opposite, lots of marketing about how product y saves z watts making us amateurs buy it, but then that test was on a already perfect setup at high speeds we're never gonna reach. But given most data is pointing to wider being better (or, not less effective but more comfortable) I'm wondering why pros aren't running wider.