Aero wheels for big tires on a CX bike, for gravel

What speed gains are to be hand running a 25.5mm inner, 32mm outer width, 50mm deep aero wheel, on a CX bike for gravel and road riding?

I dunno, honestly, the more I read into it the less it appears wheels are the panacea they are made out to be. Maybe aero stuff starts to help over multiple hours, esp for like ironman stuff, but I just don’t know if wheels make much of a difference, esp for stuff like CX.

Probably not very much. Deep rims in CX are used to stop mud clinging to the rims.

Mike

I read once that is was more to advertise the sponsors! :joy:

I have 'em. They’re light. Plus, I use them on my road disc bike as well. So, might as well.
I also have a non deep dish set. One set has file tread/fast and the other set has tires for sloppier conditions.

While @TLRozzle is talking about a CX bike, his question about aero benefits is for gravel and road rides - not CX racing. If there are aero gains to be had with wheels in road fondo’s and such, then there very likely are in gravel too. Of course the percentage gains go down as speed decreases, but for many gravel races speeds are high enough, long enough that it should matter. Just look at all the aero talk around DK200.

Another big factor is the tires and their impact on aerodynamics of a given rim profile. I’ve seen a lot of people talking about needing a wider rim (like the 25 inner width you’re talking about) to begin to maintain good deep rim aerodynamics with wider gravel tires.

If I get them, I’ll run them with a 35mm measured width, smooth tire.

My 60mm Fast Forward wheels are certainly advert heavy.

Mike

50 is maybe a little deep but carbon wheels 100% an advantage for gravel IMO

I’m drinking heavily so they’ll be here in a month, lol:
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35mm tire on a 32mm rim would violate “the rule of 105”

Not sure you’ll be getting as much aero gains as the wheel manufacturers may advertise.

I expect a newer tire to measure a touch narrower, the current ones are ~3-years old.

The tires would need to be less than 31mm on a 32mm wide rim to adhere to the 105 rule. Worth checking if the manufacturer has tested aero benefits with wider tires before shelling out the $ for a set of aero wheels.

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Check 3T C45 numbers. They claim hey are more aero w/ wider tires. Same wheels for road and gravel.

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They say they are designed for 28-30mm tires (for aero benefits) - so on the wider end of the range for road tires, but not gravel. Plus the rims measure 32mm outside width - so still wider than the recommended tire. I guess I’m a little skeptical of aero claims for gravel wheels, where the wheel would have to be very wide, and heavy, to be wider than the tire.

Course, the 105 rule may not apply universally, but seems to be a generally accepted rule in design of aero wheels based on what I’ve read/listened to.

They ship the Exploro w/ the C45s. I’m pretty sure they have a chart. Don’t have time to find it.

Edit: They ship it w/ C25s, but the C45 is designed for all tire widths and is less sensitive to tire width than other aero rims.

Check out the specialized win tunnel episode on wide tires and aero wheels. You’re still probably saving time with aero wheels, even if tire size isn’t optimal.

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Yep - that’s what the results showed. Even with 42mm wheels. The benefit was bigger with cross wind vs head on. Maybe the 105 rule is too much of a simplification, or implies there exists a “breakpoint” when on fact there isn’t a clean one, and its more a sliding scale.

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Actually, they do ship the Exploro with the C45s, but only the very Gucci Red eTap build. The C45s have been developed to also stand up to the abuse of gravel.

Ah, yes, I thought so. I’ll say I really like the C45s w/ road tires. They designed them specifically to have one aero wheel set for road and gravel. The 45s are as fast as most 60s with wide road tires.