Road bike tire size

My bike has a tire clearance of upto 38c but I usually run 23c tires inflated to 100+ PSI. I find that I keep getting flat tires more frequently and the bumps on the road feel quite intense as it is not realistic to avoid every single pothole given the traffic behind me. Today I tried to run a 32c tire for my road bike and it feels quite comfortable compared to my 23s. I was riding on rail trails for the most part with my 32s’ so I wasn’t able to make out any huge difference.

Do you run a 32c tires for your road bike? If so, do you notice that your average speed is lower? Are you able to keep up with the group during group rides?

Assuming people properly adjust larger tires to lower pressures (and all other things like tire construction and such are equal), the larger tire at lower pressure is actually FASTER than the smaller tire at higher pressures.

There are numerous articles that cover the reasons behind it, but in short, the “bump absorption” aspect in the larger tire at lower pressure leads to less energy waste. This is because of less axle displacement vertically over the micro bumps in paved/tarmac surfaces… which is faster for the same rider effort.

  • Note: This assumes a “normal” road surface with expected irregularities vs something like a perfectly smooth surface (like a dialed velodrome where HIGH pressures actually do work better), and similar tire construction with the only differences being the tire size & pressure.

The fact that you are getting less vibration to the bike and into your body may “feel” slower (less “feedback”), but it’s actually a sign of the reduced effort needed to hold the same speed.

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25s for racing. 25 or 28 in training. 100+ psi is too high. It’s individual and based on setup, but I generally run 80-90psi front, 85-95psi rear in races and I’ve been tending lower more and more. More like 70-75 in training on my tubeless setup. That’s for 180lbs combined bike/kit/rider on 25s.

That value was related to his 23 tire size. I didn’t see him list the pressure he used in the 32’s, but from his comments, I’d guess he was below that by a fair bit.

And just to add a useful link, the Silca tire pressure calculator is worth a look:

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I run tubulars and next ride I will try riding my 32s’ with 80-90 PSI instead of inflating to 100+ PSI. My 32c tires can handle upto 110PSI but such high pressure won’t make me faster as Chad said. My weight is ~70kg / 154lbs, so how do you come up with such calculations on what PSI is optimal?

See the link I shared above (likely while you were typing).

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I use the SRAM/Zipp calculator (mainly because I run 303s) and it suggests 55/58 psi for 30c. I’m 71kg, and in all honesty that’s a touch on the firm side - 52/54 seems the sweetspot.

I do think you lose a touch of speed (or at least I do) from a 25 to a 30 on reasonable roads, but the extra grip and comfort is worth it IMO.

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23 mm and 100 psi is old school. For comparison, I run about 60 psi in my 28 mm wide tires, a little lower in the offseason. The industry is in the process of moving to 28 mm as the default size and many road bike frames allow for 32 mm wide tires. Even many deep aero rims are optimized for 28 mm wide tires. Like others have said, unless you are riding only perfect tarmac, wider tires at lower pressures will be faster and have more grip (as they are less bouncy and provide more suspension travel). That’s why they are also more comfortable. IMHO I see no reason for running 23 mm tires this day and age — unless you have a masochistic streak.

There are a few tire pressure calculators. SRAM has a nice tire pressure calculator that is brand-agnostic. Adjusting for inner rim width Enve’s pressure recommendations closely track with SRAM’s. In my experience they have served as an excellent starting point for experimentation, and I usually stay close to those recommendations.

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I think the Silca calc is a good starting point. I run a hair higher than it recommends for me. I run closer to the Silca value than the SRAM one. But they kind of mark my range.

I used to run 110 on 23mm tubular wheels on my tri bike back in the day. Crazy uncomfortable. Won’t be doing that anymore when I get back into it.

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I went from 23mm tires at 100+ psi (tubes) to 25mm tires at 90 psi (tubeless) to 28mm tires at 60 psi (tubeless) and it is soooooooo much more comfortable. The bikes are different, too, but the comfort is almost all from the wider tires at lower pressures. Can’t recommend it enough!

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I’ll second this! There are so many factors that go into speed…humidity, temp, wind, weight of you/bike, phase of the moon…

If you have fast 28/30/32mm tires (e.g. Schwalbe Pro Ones, GP5000, etc.) you likely won’t be slower but you will be more comfortable! The slightly fatter tire won’t hold you back on group rides, etc.

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23s and 100PSI … wow!! You are about to start LOVING your bike a lot more, without slowing down at all.

It’s a whole new world :sunglasses:

I have never run anything less than 28s on my road bike. When I ride in group, I always ride with the fast folk … one summer I put a 28 in the rear and a 25 in front just because I was being precious, but overall I felt there was no difference other than being a bit stiffer, so I’m back to 28/28. I run tubeless, BTW.

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Gonna start calling myself “precious” when I do this on my training wheels this summer. :rofl: Like dipping my toe in the 28mm water.

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Yesterday I did a fast-paced group road ride on cracked roads with my 32s. I didn’t notice any difference in speed but the ride was ~10x more comfortable than before! I also use the same tires to ride on rail trails. I don’t think I will ever switch back to 23s at 100 PSI.

Edit: My bike (Domane AL 5) came with default 32 tires but I switched to 23s shortly after so I am just back to the factory setting.

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Most of my tyres when I started road cycling in circa 2005 were 23mm (and occasionally narrower) and I probably hung on to that for 10 years (although I think I had in higher pressures, +100psi to start with and finished with lower, 90psi or less). I probably swapped around 2014or 15 to 25mm and90 psi or less. I’ve had wider in my frame but with rim brakes and mudguards in winter thats more optimal for changing/ swapping front wheel. I am tempted to go wider but those things stop me.

You guys would have loved the days of 700 x 19c and 21c tires pumped up to 110-120 psi !!!

(my next bike will take up to 40c tires. bigger is better)

p.s. for Chad… Race wheels were Clement Criterium Seta on 28 spoke Fiamme rims with campy high flange hubs. Tied and soldered. Training wheels were GP4s on Campy NR low flange hubs and whatever tires I could get my hands on. Some Clement, some Wolblers, Vittorias. Didn’t matter, I’d ride it.

LOL, we could probably start a meme checklist about the age of a rider based on the road bike tire size & pressure they had on their first real road bike :stuck_out_tongue:

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Hellfrauds still stocked them (17,19&22mm contis) when I got into road cycling and I fell for the price, :joy: Put me off contis for a long time as everyone failed on the side wall, one of them on their 1st or 2nd ride :joy: :joy:

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120 psi and I still got a pinch flat every other week!

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I remember Conti GP in the 90s with a max pressure of 150psi! - I also had a big tube TT bike…not fun and 20 years later I find out I was also making myself slower :roll_eyes: :laughing:

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