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  • Zipp 303s in the Alps
  • sputnik
    Free Member

    I will be spending 10 days in the Alps in June. I run a set of Zipp 303 clinchers on my Look 695. Last time I was in the Alps I was running a pair of Ultegra 6800 wheels on the same bike. I still have the Ultegras, so was wondering if I should put them back on for the mountains?

    Anyone with experience good or bad with carbon clinchers in the Alps?
    I usually ride in Surrey hills where the Zipps have been fine.

    bikebouy
    Free Member

    Erm… What exactly are you worried about ?

    Perfect wheels for all manner of riding, including the Alps.

    sputnik
    Free Member

    Bikebouy my concern is long descends and overheating. Ive not had a problem here in Surrey as most descents are over in a minute or two. I guess there is a chance of rain in 10 days of riding and I haven’t ridden the 303s in wet conditions as they are on my best bike that I only use in the dry.
    I know it should be fine as Zipp are leaders in carbon manufacture and won’t have the unpredictable behaviour of no name Chinese rims.

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    c_klein87
    Full Member

    they will be fine if you’r sensible when descending and it doesn’t rain too much, i’ve used both and prefer the predictability of alu rims. i’m working as a road guide for the summer and i’m not allowed to use carbon rims

    goldenwonder
    Free Member

    I’ve seen all sort of people have problems with all sorts of wheels in the alps.
    Given how poor the braking is on carbon rims compared to alloy, I won’t run carbon in the mountains & the fact I’ve even seen Enve’s (genuine) melt even with the correct pads..

    dsb181
    Free Member

    I’d have worries about taking carbon wheels, personally I’d use the Alu brake surface ones.

    bikebouy
    Free Member

    Ahh, of course.. The Pros hacking down the Alps the other day in the Giro swapped their carbon climbing wheels at the KOM for Alloy rimmed winter rims and changed the pads too.

    Erm….

    I’ve ran Mav M40Cs throughout the Dolis and Alps and have yet to die from overheating rims/pads.

    I think you are overthinking riding bikes.

    dovebiker
    Full Member

    Provided you’re not a habitual brake-dragger, running latex tubes and fine with how they handle in the wet you’ll be OK.

    mashiehood
    Free Member

    Farsports and Enves in the Pyrenees and Alps, im still here…

    jonba
    Free Member

    I guess there is a chance of rain in 10 days of riding and I haven’t ridden the 303s in wet conditions as they are on my best bike that I only use in the dry.

    I wouldn’t be worried about them in normal conditions. This comment about not having used them in the wet would be my only concern. In ten days I’d be surprised if you didn’t get wet as thunderstorms are pretty common. Depends if you think it will make a difference taking it real easy once or twice. Maybe check the forecast as if it looks dubious take your other ones. You aren’t going to be racing so just be a bit more careful.

    njee20
    Free Member

    My FarSports rims equal my Alphas in the wet (to my amazement) using SwissStop Black Prince pads, but the risk of overheating would definitely concern me and I’d probably opt for alu rims for the Alps.

    convert
    Full Member

    I’ve even seen Enve’s (genuine) melt even with the correct pads..

    You sure about that? You really haven’t. Science eduction today….. 😉

    This is not why folk ‘fear’ carbon rims on long descents.

    I’m old fashioned though, I still find the idea of using zipps outside of race day bizarre.

    CaptainFlashheart
    Free Member

    If only someone could think of a more effective braking system…..

    🙂

    convert
    Full Member

    🙂

    bob_summers
    Full Member

    One team delammed 6 Campag boras in the Pyrenees last TdF, which not surprisingly didn’t make it to the press. I’d not be too worried as I’m not testing the materials to such limits, although that said, I did delam a rim last time.

    goldenwonder
    Free Member

    convert – Member
    I’ve even seen Enve’s (genuine) melt even with the correct pads..
    You sure about that? You really haven’t. Science eduction today…..

    This is not why folk ‘fear’ carbon rims on long descents.

    I’m old fashioned though, I still find the idea of using zipps outside of race day bizarre.

    Pretty sure what I saw with my own eyes..
    They were on a club outing over there for a few days & it warped & deformed. Maybe ‘melted’ was a touch strong.

    mikewsmith
    Free Member

    CaptainFlashheart – Member
    If only someone could think of a more effective braking system…..

    foot on the wheel?

    njee20
    Free Member

    i would also like to know what Convert is on about…

    Another report here although he’s taken the photo down.

    Not Enve:

    convert
    Full Member

    clue – you can’t ‘melt’ a themoset plastic. As I’m sure you know ‘carbon fibre’ is a composite of carbon weave and epoxy resin – it might be infused or pre-impregnated resin but its always an epoxy derivative. Which is a thermoset plastic. You can delaminate it, which will change the integral strength and create some interesting deformations and you can certainly crack it due to impact but you are never, ever going to melt it, especially not with the poxy bit of heat (in the grand scheme of things) generated by the braking of a bike wheel. The fact that other misinformed souls post it on an internet blog doesn’t make it true 🙂

    sputnik
    Free Member

    Two of my mates are back from Italy, did Monte Zoncolan on Sunday.
    Mate with the the disc equipped bike snapped 4 spokes out of the rim. Bike is a CAAD 12 disc with Ksyrium wheels.
    The wheel failed on the way down.

    njee20
    Free Member

    The fact that other misinformed souls post it on an internet blog doesn’t make it true

    So not a science lesson, but a pedantry one? Getting your rims too hot through prolonged braking can irretrievably distort the rim. Or are you questioning the possibility of that?

    I’ll bet you also tell everyone that a PIN number is a contradiction?

    Now tell us why folk do fear carbon rims on long descents?

    convert
    Full Member

    So not a science lesson, but a pedantry one?

    You can call it pedantry if it makes you feel better but it is a simple scientific fact that you can’t melt carbon fibre, or even get it a bit soft.

    Now tell us why folk do fear carbon rims on long descents?

    Whilst you can delaminate a carbon composite laminate through extreme thermal heating (probably responsible for that surface peel on your image) the biggest issue with long descents is the heat buildup in the rim (up to circa 200 deg C – CF has a relatively poor specific heat capacity and doesn’t dissipate the build up particularly well ) increasing tyre pressure, reportedly by up to 15%. That obviously increases the internal pressure on the sidewalls then add some pulsed compression by hitting a pot hole at speed (even a little innocuous one ) etc to add further pressure and you’ve internally cracked your rim. Once cracked it will probably deform quite nicely and still being hot the uninitiated will categorically tell the world they ‘melted’ their rim.

    The obvious solution to this is to reduce pre ride tyre pressure a little and not ride like a clutz through every road imperfection – hard to do in a race hence the issues some teams have reported. Oh and not being a tubby middle aged bloke dragging your brakes down an alp helps too :-).

    Of course Tubs have different but related issues with heat and glue.

    I was racing zipps (tubs) through the 90s and braking in the wet was not great – I understand this has now improved a little but not tried the latest generation of carbon brake surfaces.

    Anything else whilst I’m around?

    njee20
    Free Member

    So you’re categorically saying that deformation from carbon clincher rims is because you’ve hit something whilst the rim is a bit warm, and not a direct result of heat? Except when that is the case, but what people worry about is the former?

    I never used the word melt, you needn’t patronise me.

    mtbmatt
    Free Member

    If you are a good descender, then they will be fine.
    If you are nervous, drag the brakes or if mentally you will not be confident with the wheels then take aluminium wheels.

    Tubes can explode on aluminium wheels as well as carbon mind.

    steve_b77
    Free Member

    mtbmatt – Member

    Tubes can explode on aluminium wheels as well as carbon mind

    Right, that’s it!! I’m never riding a rim braked bike again

    convert
    Full Member

    I never used the word melt

    But others did, and you linked to that daft blog where the writer talked about their rims melting, which makes you guilty by default.

    you needn’t patronise me.

    But its always so much fun.

    So you’re categorically saying that deformation from carbon clincher rims is because you’ve hit something whilst the rim is a bit warm, and not a direct result of heat?

    You catch on fast. Ain’t science great 🙂

    Actually that’s not quite what I said. It’s nearly always because the tyre pressure is too high (because its a bit warm) but often exacerbated by hitting something to push the rim over the FoS. Straw that broke the camel’s back if you like. I will admit that heat is a cause of composite delamination so a hot rim will be more vulnerable to internal splitting caused by excessive rim force unless the right resins are selected. But it is the rim force doing the damage. And that is preventable by selecting the right pre ride tyre pressure and not riding like a berk (dragging and over things).

    The tyre is hot because the rim is hot but that is worlds away from a rim distorting because it got hot. I have an autoclave and a kiln here – you are welcome to come and heat up a rim to any temperature you please but you are not going to get it to passively distort.

    njee20
    Free Member

    It’s nearly always because the tyre pressure is too high (because its a bit warm) but often exacerbated by hitting something to push the rim over the FoS.

    Key word there being “often”, surely? The issue is largely related to clinchers, I wholly agree that it’s the pressure of the tyre, combined with the heat, I’m not suggesting there’s random spontaneous explosion of the rims (ie sticking them in an oven won’t do much). What I have issue with is your original statement of:

    This is not why folk ‘fear’ carbon rims on long descents.

    It’s exactly why folk “fear” carbon rims on long descents. They can get too hot, then fail. The exact physics behind this is pretty **** irrelevant – if your tyre explodes and you’re heading towards the concrete barrier at 40mph I’ll wager you don’t give two shits about the technicalities of the failure!

    That’s the pedantry part.

    convert
    Full Member

    The ‘This’ in your selective quote above is in response to Mr Wonder’s use of the word ‘melt’. You can call me a pedant if you like but it is just a stupid uneducated thing to say – hence my response. People (well, only daft ones) don’t fear their rims melting…because they don’t melt.

    if your tyre explodes and you’re heading towards the concrete barrier at 40mph I’ll wager you don’t give two shits about the technicalities of the failure!

    You missed the point again completely. If you live in la la land and think carbon melts then knock yourself out and don’t give two shits – there’s nothing you can do about it. Your rim will melt/distort with the heat and you will die a horrible death in the barrier. If you know why it is likely to fail you can take appropriate measures (reduce pre ride pressure and try to avoid bumps) to avoid the failure. It actually pays to know the facts…it actually matters.

    njee20
    Free Member

    What pressure is suitable to mitigate this? Serious question. You say you can get a 15% increase, so for a rim rated to 120psi you’re fine to drag the brakes on your tandem with impunity with 100psi?

    I’m genuinely curious now, as this is obviously a risk (if they’re telling guides not to use carbon rims and there are plenty of stories online of these failures – however much incorrect terminology is used), and by dropping 5psi you can avoid the problem.

    convert
    Full Member

    Well I guess if the rims/tyres are rated for 120psi on a tandem then you would be good to go.

    Take the tandem bit out of it and yes a drop of 15% would be sensible. Too many folk ride with too much pressure anyway.

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