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> Anecdotally my gravel bike is faster with 28 mm slick tires than with 42 mm sawtooth tires. Out of curiosity, do you know this to be true, or believe this to

> Anecdotally my gravel bike is faster with 28 mm slick tires than with 42 mm sawtooth tires. Out of curiosity, do you know this to be true, or believe this to be true? I ask because the perception of speed with skinnier tires is one of the things the article touches on. I felt similarly when I put GP5000 28mm slicks on the gravel bike, but when I looked at my ride history, I couldn’t really back that feeling of speed up with actual data, and evidence shows that at least in my case, there was no major difference between 28mm and 38mm. (Not saying this is the case for you, but I’m just curious).

ptmcc 5y ago
My experience is the same as yours. When I rode the same regular routes on my gravel bike on slick 38s vs my road bike on slick 25s (up from 23s, as big as I could fit!), the road bike felt faster but GPS data didn't really back it up over the course of a whole ride. The road bike is a bit more nimble with twitchier handling sure, but the more jarring ride of the skinny tires gives the illusion of speed. But in the real, non-racing world the data tells a different story. At the limit I have no doubt the road bike is ultimately faster, but that's not most of my riding. I'm not a racer but am an avid and reasonably fit recreational rider, so I ditched the road bike entirely and enjoy my more comfortable and practical gravel bike, with minimal speed penalty. Plus I can ride on dirt roads and broken pavement with ease and comfort, to boot. I think most riders are better served by gravel/endurance bikes than pure road bikes.
- 8note 5y ago
  You also want to measure the amount of power you're inputting. Could be the same speed, but you need to peddle harder to maintain it
whakim 5y ago
You're definitely faster with the GP5000s and it's not just an illusion. The GP5000 is an extremely fast tire - some of the lowest rolling resistance out there as measured scientifically [1]. Even the fastest 38mm tires are probably going to cost you minimum 10 watts per tire over the GP5000; perhaps even double that. [1] https://www.bicyclerollingresistance.com/road-bike-reviews/continental-grand-prix-5000-2018 https://www.bicyclerollingresistance.com/road-bike-reviews/c...
- kohlerm 5y ago
  They test AFAIK under ideal smooth road conditions asconfirmed by the picture. On bumpy roads the 10 watts advantage might quickly disappear
  - whakim 5y ago
    10 watts per tire is an absolutely enormous amount given that the rolling resistance of the tire itself is only 10 watts in total. The BRR test also claims that "the drum is covered with diamond plate to simulate an average road" - it isn't completely smooth [1]. If you're riding on roads that are so bumpy that you really need super low pressures (e.g. significantly lower than the 60psi you can run on a 28mm GP5000) then rolling resistance isn't a high priority. But honestly very few actual roads are that bad. [1] https://www.bicyclerollingresistance.com/the-test https://www.bicyclerollingresistance.com/the-test

ptmcc 5y ago

My experience is the same as yours. When I rode the same regular routes on my gravel bike on slick 38s vs my road bike on slick 25s (up from 23s, as big as I could fit!), the road bike felt faster but GPS data didn't really back it up over the course of a whole ride. The road bike is a bit more nimble with twitchier handling sure, but the more jarring ride of the skinny tires gives the illusion of speed. But in the real, non-racing world the data tells a different story. At the limit I have no doubt the road bike is ultimately faster, but that's not most of my riding. I'm not a racer but am an avid and reasonably fit recreational rider, so I ditched the road bike entirely and enjoy my more comfortable and practical gravel bike, with minimal speed penalty. Plus I can ride on dirt roads and broken pavement with ease and comfort, to boot. I think most riders are better served by gravel/endurance bikes than pure road bikes.

8note 5y ago
You also want to measure the amount of power you're inputting. Could be the same speed, but you need to peddle harder to maintain it

whakim 5y ago

You're definitely faster with the GP5000s and it's not just an illusion. The GP5000 is an extremely fast tire - some of the lowest rolling resistance out there as measured scientifically [1]. Even the fastest 38mm tires are probably going to cost you minimum 10 watts per tire over the GP5000; perhaps even double that. [1] https://www.bicyclerollingresistance.com/road-bike-reviews/continental-grand-prix-5000-2018 https://www.bicyclerollingresistance.com/road-bike-reviews/c...

kohlerm 5y ago
They test AFAIK under ideal smooth road conditions asconfirmed by the picture. On bumpy roads the 10 watts advantage might quickly disappear
- whakim 5y ago
  10 watts per tire is an absolutely enormous amount given that the rolling resistance of the tire itself is only 10 watts in total. The BRR test also claims that "the drum is covered with diamond plate to simulate an average road" - it isn't completely smooth [1]. If you're riding on roads that are so bumpy that you really need super low pressures (e.g. significantly lower than the 60psi you can run on a 28mm GP5000) then rolling resistance isn't a high priority. But honestly very few actual roads are that bad. [1] https://www.bicyclerollingresistance.com/the-test https://www.bicyclerollingresistance.com/the-test