Is a true 33mm CX tire faster in a CX race? (vs a gravel tire)?

[rockdude]

Its course specific, Last weekend, I won on fat tires on an extremely bumpy new course, this coming week we are racing on grass and I will be on 33's. Fat tires on grass roll like on Velcro. For most races, I will be on 33s, they spin up faster and roll faster in most of the conditions we race here in Colorado.

[gravelreformist]

This is totally course and condition-specific. Cross is perhaps more sensitive to tire selection than any other discipline of cycling. Width, tread pattern, rubber compound, tire construction, pressure, all play a role in what makes for the best tire on a given day. You can't make any blanket statement as to which tire is faster than another.

If you're just racing for fun, it doesn't matter nearly as much. If you're racing for results, I'd want some 33's available.

[polyhistoric]

I'm gonna roll back to 33s this year. Tried some Grifo 38s and felt more tire roll and rim strike. I also don't think the tread pattern on the Grifo 38 was great - very spaced with not enough corner grip when really leaned over. That being said, my old man back really loved the extra volume and cushion over the rocks and roots. Just need to find a better 38+ treat that suits my riding.racing style.

[rothwem]

Originally Posted by quickfeet

I’m sure it totally depends on the course a the rider whether or not 33mm is faster.

Are you a good technical off-roader? If no, then a wider tire will help.

Is the course through the woods or on a rough course? If yes, then a wider tire will help.

Tires have a max size in cx because the point is to have less traction in certain conditions so you need to get off and run. There is a reason MTB racers have bigger tires. The goal is to stay on the bike in rougher terrain.

I saw Jonathan Page protest an early season cx win from Carl Decker in Utah around 2010ish because Carl rode up the stairs on a run up on the last lap. Page was definitely not doing that on 33mm tires.

Hm. I am a good technical off-roader. Maybe I should go narrow.

Originally Posted by rockdude

Its course specific, Last weekend, I won on fat tires on an extremely bumpy new course, this coming week we are racing on grass and I will be on 33's. Fat tires on grass roll like on Velcro. For most races, I will be on 33s, they spin up faster and roll faster in most of the conditions we race here in Colorado.

Hmm, yeah the courses here have a lot of grass. I guess narrow means less blades of grass to bend over.

Any thoughts on how big a “33” would be if I mounted them on 24mm internal road rims? Should I be worried about smacking the rim edges?

[.RJ]

Originally Posted by polyhistoric

I'm gonna roll back to 33s this year. Tried some Grifo 38s and felt more tire roll and rim strike. I also don't think the tread pattern on the Grifo 38 was great - very spaced with not enough corner grip when really leaned over. That being said, my old man back really loved the extra volume and cushion over the rocks and roots. Just need to find a better 38+ treat that suits my riding.racing style.

I never loved the grifo tread either, I always thought the baby limus was a better all conditions tire.

[.RJ]

Originally Posted by gravelreformist

This is totally course and condition-specific. Cross is perhaps more sensitive to tire selection than any other discipline of cycling. Width, tread pattern, rubber compound, tire construction, pressure, all play a role in what makes for the best tire on a given day. You can't make any blanket statement as to which tire is faster than another.

Maybe for the pros.

For the rest of us I bet we'd all fail the pepsi challenge or that everything has trade offs that show themselves on different courses or different conditions, or even different parts of the course. The CX race I put on with my team has a mix of everything so there's really no "best" tire unless its very muddy.

And still, amateurs probably need to pick one, or possibly 2 different tires to have for the whole season. I guess that doesnt feed the bike racer equipment neurosis though.

tl;dr dont overthink it too much, signed, a guy that used to glue up 3 sets of tubulars every fall

[benb]

It takes a huge stretch of logic to think a 30 or a 32 is faster than a 25 on the road but that you shouldn't take a 35, 38, or 40 on a cross course if you can get away with it.

I barely ever did any cross but the singular most fun moment of ever trying it for me was taking my MTB and riding up a staircase that was in the course instead of running up it.

I think it's a whole bunch of irony cause every race I ever spectated the fans were all waiting with baited breath to see if anyone rode/bunny-hopped the biggest obstacle on the course and then would go nuts when someone did it. I feel like I had to have seen Jonathan Page do this once and the crowd went nuts.