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Cross tire size for a slower category
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The more hardcore topic appears dead in the "33".

I figured out my Velocity USA wheels that came on my cross bike are the 23mm wide tubeless. They're setup already also with the right tape, it appears. Looks like I just need the valve stem and sealant and tires. I have a shop compressor I can inflate it with first time to seat it.

Thing is, I race 4/5. I'm not old enough for masters 40+ for another 4 years. So, I'm pretty much limited to racing 4/5 as around here there isn't a 3/4 like for crits. In 4/5 it always seems I have the smallest tires. I didn't know any better and bought 33mm way back. I read up on it, and it seems even if I ever went to a USAC regional for my level that 35mm would still be the larger max. Not 33. Now, in 4/5 around here everyone looks like they're on easily 38mm or larger off road tires. Once in a while some young kid on a mountain bike laps the field in 4/5.

If that's all true.........any harm in going with a 38 (most I can fit) instead of a 33? Even a 35 seems like it would gain me some grip (which is where I currently suck).

I really don't want to train/race on different tires since I train a lot on gravel riding in cross season and would prefer the 38 for that.

If I'm out to have fun and not make Cat 3 or win regionals..........no harm in the 38's? I was thinking something like a Terreno 38. Then put my clincher mud tires on the spare wheelset just in case weather throws a wrench in plans. I can't convert that set tubeless as it is road tubeless, too high a pressure for seating/running a cross/gravel tire I think.

Just trying to feel out the practical implications of rules versus the norms of tires I'm seeing out there. Thanks.
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Re: Cross tire size for a slower category [burnthesheep] [ In reply to ]
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nobody cares until the official checks your tires at the start grid with the UCI 'go/no go' caliper.

Anne Barnes
ABBikefit, Ltd
FIST/SICI/FIST DOWN DEEP
X/Y Coordinator
abbikefit@gmail.com
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Re: Cross tire size for a slower category [burnthesheep] [ In reply to ]
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I think you're USA based off of your posts. There's not any tire width "rules" for cyclocross for you unless you're a elite/pro or racing at nationals (and even nationals is a mixed bag for enforcement). Even USAC regional events or non-pro categories at UCI events like Trek CXC (run under USAC rules for non-elite/pro riders) do not have tire width restrictions.

If you're in the USA and paying for your own tires, it's about a 99% chance you do not have tire width restrictions to worry about.

Larger tires are going to give you better resistance to burping at low pressure and lower pressures is more important to grip than specific tread patterns. That's one of the bigger perks of going for larger tires. Tubeless rim and tire combinations for cross is a pretty big rabbit hole to go down though.

The real question is where do you live that will have a cross season?
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Re: Cross tire size for a slower category [dangle] [ In reply to ]
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dangle wrote:
I think you're USA based off of your posts. There's not any tire width "rules" for cyclocross for you unless you're a elite/pro or racing at nationals (and even nationals is a mixed bag for enforcement). Even USAC regional events or non-pro categories at UCI events like Trek CXC (run under USAC rules for non-elite/pro riders) do not have tire width restrictions.

If you're in the USA and paying for your own tires, it's about a 99% chance you do not have tire width restrictions to worry about.

Larger tires are going to give you better resistance to burping at low pressure and lower pressures is more important to grip than specific tread patterns. That's one of the bigger perks of going for larger tires. Tubeless rim and tire combinations for cross is a pretty big rabbit hole to go down though.

The real question is where do you live that will have a cross season?

Freaking sweet.

Tired of knowing I'm hemorrhaging time every corner. Plus, my wife's freaking greenway bike has bigger tires than my cross bike right now! Geez! That thing has 35's. I'm on 33's.

Next then is measuring my stays and current gap to the chain to make sure I buy the best I can do.
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Re: Cross tire size for a slower category [burnthesheep] [ In reply to ]
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I generally run Ritchey Megabite wcs 38mm on 26mm ID rims and save for two untimely burps over two seasons freaking love them for most everything except mud (cat1/ss) was going to try cushcore inserts this year but pretty sure I'm not racing so that experiment is on hold
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Re: Cross tire size for a slower category [burnthesheep] [ In reply to ]
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The "official" max size for USA cycling Masters is 38mm. Some promoters don't care what you run...which is great! If they don't want tires wider than 33mm having an advantage then they need to design their courses appropriately. It's on them I say.
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Re: Cross tire size for a slower category [stonerider] [ In reply to ]
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stonerider wrote:
The "official" max size for USA cycling Masters is 38mm. Some promoters don't care what you run...which is great! If they don't want tires wider than 33mm having an advantage then they need to design their courses appropriately. It's on them I say.

I bought the 38's. Vittoria terrenos mix.

The course I ride most in town I could easily gain 20sec a lap on a 7min lap on tires biting more. Fitness wise there's no gaps to fill. I can do barriers fine. It's literally cornering speed and speed over rougher terrain with less tire volume.

I need to try some more courses out of town.
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Re: Cross tire size for a slower category [burnthesheep] [ In reply to ]
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Just to add, if you want to eliminate burps and run a lower pressure without losing sidewall support, Cushcore makes an CX insert: https://www.cushcore.com/kit-specs/

Downside: you will likely curse a lot more during tire install and removal.
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Re: Cross tire size for a slower category [burnthesheep] [ In reply to ]
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Somewhat on-topic, anyone have experience racing CX near the pointy end of a regional/state/provincial race on a gravel bike? I feel like traditional CX bikes are designed for World Cup style racing by skilled cyclocross riders and the geometry is conservative. I was watching a couple of World cups online and the courses looked different with big off cambers, big downhills into corners, big straightaways into u-turns, whereas the courses I normally race on are tighter, twistier, slower. I'm curious because I want my next off road drop bar bike to have clearance for 2" tires.
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Re: Cross tire size for a slower category [pknight] [ In reply to ]
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I would think the gravel geometry ought to be more stable than traditional CX geometry and as such traditional CX geometry is better on slower, twistier corners.

Regardless, it is most certainly possible to be competitive. Joris Nieuwenhuis raced the WC season last year on an Aspero. The biggest question, in my opinion, is whether shouldering a frame is important for your racing and if so, whether your gravel frame can easily be shouldered.

Next, beyond that is weight: I know my Cruxs are significantly lighter than my Aspero.
Third, I know my CX bikes are more compliant than the Aspero, but that will change based on Gravel model.

I believe that geometry will make a bike feel differently, however these geometry changes are so small that they will not have a major impact on lap times.

The above poster is a physiologist employed by PEARL iZUMi. However, statements are not made on behalf of nor reflective of PEARL iZUMI in any manner... unless they're good, then they count.
Last edited by: xtrpickels: Aug 26, 20 11:55
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Re: Cross tire size for a slower category [burnthesheep] [ In reply to ]
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burnthesheep wrote:
stonerider wrote:
The "official" max size for USA cycling Masters is 38mm. Some promoters don't care what you run...which is great! If they don't want tires wider than 33mm having an advantage then they need to design their courses appropriately. It's on them I say.


I bought the 38's. Vittoria terrenos mix.

The course I ride most in town I could easily gain 20sec a lap on a 7min lap on tires biting more. Fitness wise there's no gaps to fill. I can do barriers fine. It's literally cornering speed and speed over rougher terrain with less tire volume.

I need to try some more courses out of town.

Keep in mind that drills and practicing skills will take you further than tires alone.
With that said, I wonder how you'd fair with a less-aggressive tire in the larger size: Those Vittorias grip like Velcro... but roll like it as well.
A Continental Terra trail, while slower than the Terra Speed, may offer a good balance between speed and grip.

The above poster is a physiologist employed by PEARL iZUMi. However, statements are not made on behalf of nor reflective of PEARL iZUMI in any manner... unless they're good, then they count.
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Re: Cross tire size for a slower category [burnthesheep] [ In reply to ]
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Depends on your strengths and weaknesses. I can't handle or corner for shit on my CX bike, so I select tires that have more advantage on hard faster surfaces
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Re: Cross tire size for a slower category [burnthesheep] [ In reply to ]
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Go with 38's if you can.
Watch out for toe overlap on your front tire. I ran 38's on a traditional CX bike last season and had lots of overlap, even with my small feet.
As far as running a gravel bike, one of our local elites had no problem winning on his Diverge. Liked it more than his Crux.
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Re: Cross tire size for a slower category [Rumpled] [ In reply to ]
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The Giant PA2 worked. Did two wraps of Stans and sealant with Vittoria Terreno Mix in a 38.

First ride the gravel was looser than normal but a whole mph faster overall. I would have pinch flatted at least once on clincher.

Ill do a cross workout soon. But so far awesome.
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Re: Cross tire size for a slower category [pknight] [ In reply to ]
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I race 45A on an Ibis HakkaMX... which I guess is technically now a gravel bike with cross bike heritage roots. In any case, that same frame is raced by the guys that are regularly (ie ALWAYS) on the podium (Don Myrah being one of them). So, yeah, you can race CX on a gravel bike just fine.

As for the original question regarding tire size, most guys here in the Bay Area are running 35-38 but the courses dictate the tread pattern. I raced almost exclusively on 35c Kenda Happy Mediums last year (25psi on 24mm inner width rim). Although, my best placing last year (5th) was on a SUPER bumpy course running 27.5x2.1 Schwalbe Thunderburts at 18psi. =)
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