Descending with carbon clincher still an issue?

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Marin
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by Marin

riochang wrote:
Marin wrote:What wheelset were you using for this descent?


Farsports 38x25mm U-Shape clinchers on Novatec Hubs, Vittoria Open Pave 27mm, Vittoria latex tubes.

eric
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by eric

If you go too slow and brake too much you can have problems. Reasons might include not being a confident descender, going down a very steep and technical (many tight turns) descent, getting stuck behind slow traffic.

Last year I did a sportif type ride in SoCal with a teammate. We're both confident descenders and weigh around 66-68kg. We were both on FarSports rims. The course included an extremely steep descent. Concerned about my rims I bombed it as fast as I was comfortable going. Concerned about his rims, my teamate went uncharacteristically slow. He melted a rim, I didn't.

High speed descents are pretty safe. As noted already the wind convects heat away from the rims. And you're slowed by wind resistance. It's the slow descents with super tight turns that you have to worry about. There's some roads where I live that are > 10% and have many turns marked 10 or 15 mph. I won't ride carbon clinchers down those. Unfortunately the road I live on is like that.

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halvard
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by halvard

As others have pointed, they are OK if you descend at a normal speed.
For me a bigger issue is performance (or lack of) in wet conditions. I have had serious problems with my Zipps, using their recommended Zipp pads.

KWalker
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by KWalker

I've descended Mt. Diablo countless times on carbon clinchers and butyl and latex tubes alike. No issues with the right pads. Most of my rides have around 3k feet of gain/loss in only 1.5-1.75hrs and on any weekend ride I can hit 7-9k of climbing/descending. So if there were issues I'm sure I would have encountered them.
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riochang
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by riochang

Thank you for the input KWalker, what wheelset were you using for those descents?


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KWalker
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by KWalker

I've used Zipp 404 Firecrests, Roval CLX60s, November Rails
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Nejmann
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by Nejmann

KWalker wrote:I've used Zipp 404 Firecrests, Roval CLX60s, November Rails


This is just what I want to hear. I'm gonna try my zipp 404 on stelvio/italian alps later this year. And bring some money for a wheelset, if it doesn't work. i'm a 200lbs rider.

spdntrxi
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by spdntrxi

I'm 185 and have no issues coming down Diablo even slowed by vehicles with Enve 3.4s


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riochang
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by riochang

great to hear!

KWalker
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by KWalker

I'm a 150-155lb rider FWIW. If I was 200, I'd think differently since there is a lot more mass to slow down.
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dadoflam08
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by dadoflam08

fromtrektocolnago wrote:I think the bike companies and wheel builders solved this issue by agreeing to sell us disc brakes.


Exactly - disc brakes address the key shortcoming of carbon rims

No-one has solved the fundamental issue that carbon rims under hard rim braking will achieve a temperature that can cause deformation - it is the nature of the material and the need to use friction to stop. The braking surface and pads have improved braking performance but it is still possible to damage the rim or pop a tyre off the rim despite development to this time.

Nejmann - just curious - why would you lug a set of 404 clincherss up Stelvio? - I would have thought that the issue we are discussing, heavy rims mass and cross winds will be much more of a consideration than aero benefits(?) - particularly for someone your weight (I'm same )
Last edited by dadoflam08 on Tue Mar 01, 2016 6:57 pm, edited 1 time in total.
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Calnago
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by Calnago

Disc brakes on a high end road bike introduce far more issues than they resolve.
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by glepore

Just to echo the above comment, if you're not racing, and your primary goal for the day/trip is climbing, I'd leave the 404's at home and take a nice pair of light clinchers ie something like a c24. Its not like the 404's have a width benefit or something on top of the aero.
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MRM
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by MRM

Don't the new Zipp 404's (Firestrike & NSW's) have a silicon carbide brake track to combat this problem? Maybe someone who has ridden them can substanciate.

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dadoflam08
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by dadoflam08

Calnago wrote:Disc brakes on a high end road bike introduce far more issues than they resolve.


maybe - maybe not - but they they are a solution to the issue of rim braking on carbon rims and enable carbon to be used to its full potential rather than trying to make it do what it is not inherently good at.

"Don't the new Zipp 404's (Firestrike & NSW's) have a silicon carbide brake track to combat this problem? Maybe someone who has ridden them can substantiate"

- may improve the breaking performance but I would be highly surprised if it reduces the temperatures that can be attained that will affect the carbon structure it is attached to. Not sure how you would substantiate that claim - at best nothing happens - Zipp at its marketing finest
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