All round carbon wheels - Cosmic Pro SL UST or new Firecrest 303

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JamesCB
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Joined: Fri Jun 15, 2018 7:07 am

by JamesCB

I’ve spent a week with a boxed set of the new Zipp Firecrest 303 (weighed in at 1550grm with rim tape) wondering whether or not to get the Mavic Cosmic Pro SL UST instead and go tubeless. Lots of good reviews of the Cosmics but the 303s are as yet untested in the usual media. Does anyone have any experience of the 2 they can share?

zefs
Posts: 99
Joined: Sat Aug 05, 2017 8:40 pm

by zefs

I can comment on the UST tubeless aspect, have the Ksyrium Elite wheels and tubeless works great so I would go with Cosmics.

*Tyres mount/unmount by hand
*They seal with floor pump
*They stay seated when deflated

Not sure why Mavic uses tubeless tape on the carbon ust wheels though, Ksyriums are built without holes.

by Weenie


JamesCB
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Joined: Fri Jun 15, 2018 7:07 am

by JamesCB

Thanks for the response. It's the ease of tubeless that really appeal for the Mavics, having had nightmares before with Schwalbe Pro Ones and Pacenti rims. The new Firecrest rims (previous version of the NSW apparently) are reputedly very fast and top of the pile for braking. Any weight saving on the rims is probably offset by the inner tubes though.

Hard to ignore the price difference too at circa £500. If the Firecrest performance is that much better they must be amazing. Heart is saying Zipp but the head, wife and wallet would say Mavic I think!

jlok
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by jlok

Wait for the new Ultimate UST?
Giant Propel Advanced SL Disc 1 < Propel Adv < TCR Adv SL Disc < KTM Revelator Sky < CAAD 12 Disc < Domane S Disc < Alize < CAAD 10

guyc
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by guyc

jlok wrote:
Fri Jun 15, 2018 4:55 pm
Wait for the new Ultimate UST?
Over twice the cost....

JamesCB
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Joined: Fri Jun 15, 2018 7:07 am

by JamesCB

Out of budget range, sadly.

TobinHatesYou
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by TobinHatesYou

jlok wrote:
Fri Jun 15, 2018 4:55 pm
Wait for the new Ultimate UST?
At $4250, I'd expect lighter than 1310g for 40mm deep, 26mm wide tubeless clinchers.

Also I found this funny and pertinent to and previous debate about the hardness of carbon rim brake-pads:

"Technically, you can still run the yellow pads on these, and they won’t actually damage the rim, but because the fibers are exposed and they will heat up, you might be able to see the woven pattern get a little misshapen over time. That’s normal, according to Mavic. But the new pads will do that less, and they’re replacing the yellow pads altogether. That said, they strongly recommend (and require it to maintain your warranty) you use their pads because harder pads (even the excellent SwissStop Black Prince) can damage the rims."

via BikeRumor.

RyanH
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by RyanH

Carbon spoked rims ride differently than steel spoked rims. The old CCUs were not anywhere close to ww wheels either at 1180g for tubs. What they are supposed to provide is a unique ride characteristic. For Mavic, they went after ultimate stiffness and trust me, it's a wild wheel to ride. It's also a fairly harsh ride. Lightweight on the other hand isn't ultimate stiffness but instead an amazing blend of stiffness and comfort and speed. So, for these wheels it's not just about weight but actually how they ride.

With that being said, I rode the 2017 version of the Cosmic Ultimate and returned them. Fortunately they were defective but I would have tried otherwise. Mavic doesn't know how to make a wheel that doesn't feel like you're riding through peanut butter. Maybe they fixed that this time around.
Strava
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JamesCB
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Joined: Fri Jun 15, 2018 7:07 am

by JamesCB

So I’ve got them both for a weigh in. Put some conti race 28 inner tubes and Michelin Power Competition on the Zipp Firecrest and weighed the Mavic Cosmic, as supplied, without sealant. Minus QRs Zipps are 2195 grms and Cosmics 2071. Factor in the QRs as supplied and you get Zipp 2280 vs Mavic 2180. The sealant will reduce it by about 60 grms so really no weight difference to talk about.

No idea which way to go...

TobinHatesYou
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by TobinHatesYou

Get the wheels that match your inflated tire widths if you have a preference for Michelin’s Power Comps for example. IIRC Michelins are very plump.

JamesCB
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Joined: Fri Jun 15, 2018 7:07 am

by JamesCB

Surely it makes more sense to buy the tyres for the wheels? Anyway as we know the Mavic are sold as a package. I don’t think my decision will be based on my current tyre choice. I like the Michelin but wouldn’t ride them in the wet where I prefer GP4000s.

TobinHatesYou
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by TobinHatesYou

JamesCB wrote:
Sun Jun 17, 2018 10:43 pm
Surely it makes more sense to buy the tyres for the wheels? Anyway as we know the Mavic are sold as a package. I don’t think my decision will be based on my current tyre choice. I like the Michelin but wouldn’t ride them in the wet where I prefer GP4000s.

Technically yes, but practically the Mavics are just a hair over 25mm wide externally with a 19mm internal width. That's and odd choice since many 23mm tires mounted on those rims will be around 26mm.

JamesCB
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Joined: Fri Jun 15, 2018 7:07 am

by JamesCB

I think they are designed to work best with 25mm tyres, indeed that is what they are supplied with and the Hutchinson made UST tyres get fairly good reviews unlike the Mavic made standard Yksion.

It's true the Zipp are wider at the brake track but with a narrower inner width. Having inflated 25mm tyres on both rims the transition between tyre and rim appears smoother/more streamlined on the Mavics. In reality I'm only going to use 25mm tyres. Sadly the Zipp NSW are out of price range as they would seem to offer the best of both worlds.

The questions are, which is going to offer best return for the money? Is tubeless now becoming the way forward for road wheels? Are the Zipp going to be easier to service and repair in the future and if so are the hubs likely to outlast the rims thereby necessitating a rebuild.

Finally which are going to be or feel faster - in various conditions?

by Weenie


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