Wheels - trade off in rim depth aero vs. weight

FrankGrimes

Is there any good comparison of the differences in speed advantages you gain from different depths of rims on the flat versus the cost of heavier rims on uphills available online (ideally in a quantifiable form)?

I have a pair of Mavic Cosmic Carbones carbon/aluminium clinchers (with PowerTap SL+ 2.4 hub) but I never really warmed to them as I felt I didn't get great momentum with them on uphill segments. They've barely been used as a result and I was thinking of selling them to fund the purchase of new wheels on the Rose CW Team bike I'm hoping to buy for racing.

I have some DuraAce C24s from 2011 and absolutely love them - really light for long climbs and accelerate quickly, but I also feel they roll great and I have never felt like I was missing speed on the flats with them. As I'm a bigger guy, I'll be looking to hang on in climbs in races and then hopefully gain some ground on the flats. For that reason, I was going to rule out 50mm rims as I feel they could cost me too much time on climbs (more than they'd gain me on the flats?).

As I love the C24s, I'd consider sticking with DuraAce wheels, and so I wondering if the C35s might be a good compromise as they might give some aero benefits but are only about 100g heavier than the C24s. I haven't found much info on the C35s (not the new versions anyway) on here or online so wanted to check if anyone has experience of them, or, even better, if there was some data that showed the trade-offs between rim depth aero gains vs. weight losses, that'd be schweet.

blorg

I think I'd stick to the DuraAce C24s, they are meant to be very good wheels. I know what you mean about the inertia on Cosmic Carbones (I have a pair myself) but to be honest I doubt any of it makes that much difference if you are talking lower cat amateur racing. You are talking about tiny tiny percentage reductions in the overall system of bike+rider. You can lose the 250g or whatever it is off your belly a lot more cheaply than off your wheelset.

Roues Artisanales has the go-to test for getting an idea of the aero benefits: http://www.rouesartisanales.com/article-15505311.html; other articles I've seen about aero suggest you will gain a lot more from working on your position than spending on a wheelset.

karlmyson

I've been riding Dura Ace C24s since July last year and they're the best wheels I've ever experienced. I'm not a natural climber, but they allow me suffer more on the long hills and not be dropped there as easily. Anywhere other than a hill I'll hold my own with most. The wheels climb great, accelerate and sprint well, and TT well too, and for very light wheels they are strong, an important quality needed on Irish roads. I can't compare them with deep section wheels as I've no experience of them. I do think the C24s are a very fine wheelset though. Personally, even though I like flat TT'ing, I'd be surprised if deep sections made _that_ much of a difference.

lennymc

I have a set of rs80 24 mm (1521g) and a set of planet x 50 mm clinchers (1796g) (both weights according to planet x website) and to be honest, there is no real noticeable difference in going up hills. Certainly none that I can see anyway. I must put on one set and do a hill, then try again with the other set (same power, conditions etc) for the craic to see if there is any difference. I weigh about the same as you, and in my experience 250g aint gonna make any difference to how hard it is getting up that hill

FrankGrimes

Thanks folks. Agree that it's not going to be major in the scheme of things. That said, I know a few lads that swear by their deep rim wheels, though admittedly they are A1/A2 riders so may notice more difference at that level.

I think I may go for C35s if I do buy the bike as there's very little difference between them and C24s in terms of weight and if I find they are less quick uphills, I'd then have the option of swapping them out for the C24s. At 35mm there's bound to be a little bit of aero gain so they might be decent on flatish races.

Gotta say though, the C24s are pretty much the perfect wheel in my opinion for all the reasons karlmyson lays out.

dave_o_brien

Go for the new set, it will make you win more and get many ladies.

So... how much are you looking to sell the Cosmic's for?!

colm_gti

To be honest, I'd be more interested to hear the tubular vs clincher debate. Are tubular tyres still faster than clinchers, or has clincher technology caught up?

TheBlaaMan

colm_gti wrote: »

To be honest, I'd be more interested to hear the tubular vs clincher debate. Are tubular tyres still faster than clinchers, or has clincher technology caught up?

They're more puncturey in any case

:D:D

HTH

colm_gti

TheBlaaMan wrote: »

They're more puncturey in any case

:D:D

HTH

But which is FASTER

TheBlaaMan

colm_gti wrote: »

But which is FASTER

The ones that stay inflated......;)

FrankGrimes

Yeh, should've said I was looking at clinchers only as I'm not mad about tubulars. Just don't like the extra messing around with glue etc. And though the risk of problems with the tubs being poorly glued, coming off etc. is low, it's still higher than the risk with clinchers.

That said, I'm also quite wary of carbon as a braking surface from the brief time I had testing it out, I just prefer the reassurance of the instant bit of Swissstop brake pads on aluminium - I descend quite fast so I value that reassurance. Extra weight for aluminium rims over carbon is definitely one tradeoff I'm happy to make to get what I feel is a safer option, particularly in the wet.

If I decide to sell the Cosmics with the Powertap SL, I'll whack it up on the adverts section here.

petethedrummer

There's a very good discussion on wheel choices in the 2nd half of this podcast: http://velocastcc.squarespace.com/tech5/2013/1/6/episode-2-meet-rich-land.html

The main piece of advice was .... lose some weight!