Mountain descending on carbon rims - real world experiences?

bigpikle
bigpikle Posts: 1,690
edited February 2013 in Road general
I'm considering a nice set of carbon rims and a key use for these will be events and trips in the mountains - Alps, Pyrenees and others. I've a good bit of experience riding there over recent years and in mass participation events such as the Maratona etc, but always used traditional alu clinchers in the past. Being both lighter and more aero than my current rims I'd be planning on using these for events like the QBH, Marmotte and similar as well as riding with friends on informal or solo trips.

My concern is about braking and I'd really like to hear REAL WORLD experiences from those that have ridden both alu clinchers and carbon tubs in these kind of environments. What are the real differences in dry conditions, which is typical of 95% of past rides I've done, and just how bad does it get in the wet? Does it just require a different style of riding or is it just plain hard to slow down?

I'd consider myself a 'middle of the road' descender in terms of skill and bravery. I happily leave a lot of people behind in normal conditions but am not up there with the super fast/brave/lunatic guys we all know and love/hate....
Your Past is Not Your Potential...

Comments

  • TakeTurns
    TakeTurns Posts: 1,075
    I assume you mean full carbon rim including the braking surface. I've got no experience riding them. Although, I've heard Swisstop yellows work great with them and that they perform just as well as an alloy surface.

    I do believe however, it boils down to the quality of the rim.
  • I used a pair of 303 tubulars this summer for the Haute Route - stage one was the first time I had ever ridden with carbon rims or tubulars and after years on trusty Cosmics I was nervous. I'm a good descender and found the 303s to be better descending than my Cosmics - they were especially quick in and out of tight hairpins and the first descent I put them into was the Columbière and I was seriously impressed. Braking was excellent; possibly better than my Cosmics and at least as good (only tested in the dry).

    My big worries were rain - didn't really have any; and flats - I'm told tubs are far more resistant. I had four flats last season - three were pinch (wouldn't have happened with tubs I'm told) and one glass shard in Vancouver after a rain storm.

    I noticed on the Haute Route most people had alu clinchers, but then where I ride in Switzerland, most people have carbon tubulars. If it starts raining on a ride and I have a descent to do then I go easy anyway - and I never head out if it's already raining. That might upset a lot of Brits but that's just the way it is here... club rides are cancelled if there's rain!

    Good luck!
  • I use Mavic Ultimate tubulars. I the dry they're pretty good, not much between them and alu clinchers (which i use on rare occasions).

    But in the wet, it ain't great, and definitely worse than alu. I did the Etape 2 last year in the wet and cold, and descending was no fun at all. You have to keep the brakes lightly feathered at all times, or you have a 2 to 3 second delay before anything happens at all. I lost a lot of time on the descents and was overtaken by lots of people, whereas in the dry I usually descend pretty well.

    On this years Etape i may well take a front alu wheel with me just in case it's a rainy day.

    So in summary, it's all good, just not when it rains.
  • These days with the right pads, DRY braking with the TUBULARS is good. Wet braking is not as good and doesn't inspire confidence.
    If you ride in the alps in summer there is no reason to be too worried. I would use glue rather than tape for your tyres, my experience with tape and long steep descents is not great... the tape overheats and slips a bit... you can see the valve at an angle to the rim.
    left the forum March 2023
  • elderone
    elderone Posts: 1,410
    I have no experiance of these wheels but i watched a utube clip about a mass ride I think from geneva to nice and a chap had a tube pop due to heat generated from his carbon wheels under braking.No idea how often this happens but looked scary tbh.
    Dulce et decorum est Pro patria mori
  • elderone wrote:
    I have no experiance of these wheels but i watched a utube clip about a mass ride I think from geneva to nice and a chap had a tube pop due to heat generated from his carbon wheels under braking.No idea how often this happens but looked scary tbh.
    Yes but the OP has tubular tyres, so this is not an issue for him
    left the forum March 2023
  • markos1963
    markos1963 Posts: 3,724
    Most of the so called horror stories regarding blow outs on long Alpine descents come from overheating on clincher rims. According to a carbon repairer I was speaking to what happens is the rim heats up passes it through to the tube which forces the bead off the rim causing a blowout. So if you are using carbons tubs you would be ok as this can't happen. My carbon tubs(Gigantex rims) are very good brakers in the dry, so so in the wet but that is with standard pads.
  • I used a pair of 303 tubulars this summer for the Haute Route - stage one was the first time I had ever ridden with carbon rims or tubulars and after years on trusty Cosmics I was nervous. I'm a good descender and found the 303s to be better descending than my Cosmics - they were especially quick in and out of tight hairpins and the first descent I put them into was the Columbière and I was seriously impressed. Braking was excellent; possibly better than my Cosmics and at least as good (only tested in the dry).

    My big worries were rain - didn't really have any; and flats - I'm told tubs are far more resistant. I had four flats last season - three were pinch (wouldn't have happened with tubs I'm told) and one glass shard in Vancouver after a rain storm.

    I noticed on the Haute Route most people had alu clinchers, but then where I ride in Switzerland, most people have carbon tubulars. If it starts raining on a ride and I have a descent to do then I go easy anyway - and I never head out if it's already raining. That might upset a lot of Brits but that's just the way it is here... club rides are cancelled if there's rain!

    Good luck!

    This is good to know. We’re based in La Giettaz in July at the foot of the Aravis and up the road from Megeve where you lot stayed on the first night. So stage one and two of the Haute is our ‘playground’. I was humming and hawing about taking my 303 tubs but I think I’ll bite the bullet.
  • I used a pair of 303 tubulars this summer for the Haute Route - stage one was the first time I had ever ridden with carbon rims or tubulars and after years on trusty Cosmics I was nervous. I'm a good descender and found the 303s to be better descending than my Cosmics - they were especially quick in and out of tight hairpins and the first descent I put them into was the Columbière and I was seriously impressed. Braking was excellent; possibly better than my Cosmics and at least as good (only tested in the dry).

    My big worries were rain - didn't really have any; and flats - I'm told tubs are far more resistant. I had four flats last season - three were pinch (wouldn't have happened with tubs I'm told) and one glass shard in Vancouver after a rain storm.

    I noticed on the Haute Route most people had alu clinchers, but then where I ride in Switzerland, most people have carbon tubulars. If it starts raining on a ride and I have a descent to do then I go easy anyway - and I never head out if it's already raining. That might upset a lot of Brits but that's just the way it is here... club rides are cancelled if there's rain!

    Good luck!

    This is good to know. We’re based in La Giettaz in July at the foot of the Aravis and up the road from Megeve where you lot stayed on the first night. So stage one and two of the Haute is our ‘playground’. I was humming and hawing about taking my 303 tubs but I think I’ll bite the bullet.

    If you spent all that money to leave them at home on the best cycling trip of the year, that would be a right waste of money, wouldn't it?
    Of course you need your best wheels when you go to the Alps FFS...
    left the forum March 2023
  • It was either the Zeros or the 303's - the former have lots of plus points going for them as well.
  • sungod
    sungod Posts: 16,522
    carbon+tubs vs. alloy+clinchers...

    on gentle gradients i don't find much difference

    on steeper ones, say 12-15% and upwards, i find it does take more force on the levers to brake, and balancing front-rear braking becomes essential if you want the shortest stopping distance

    i wouldn't like it in the wet

    the other thing to watch for if you've not got many miles on the deeper rims is how they behave on windy days, on straight roads it's fine, but can be unpleasant on a twisty descent where the wind angle is changing and maybe gusty too, especially if there's traffic and you can't take the best line
    my bike - faster than god's and twice as shiny
  • bigpikle
    bigpikle Posts: 1,690
    Thanks guys - some great info and much appreciated.

    They will be all carbon tubs as suggested. I rode the Maratona with a guy that had a bad experience with a set of carbon clinchers with a big tyre blowout on a fast descent. He was a very experienced ex-high level racer as well, and knew how to ride!

    I'm only thinking summer use in the mountains but they'll get some use back here as well when the conditions are suitable. I'm not sure whether to go for a 38/50mm combo or the full 50/50mm as an all-round set though. I guess the 38mm front might make the handling a little easier on windy days but I dont know how much real world difference it actually makes? I'd love a set of 303's but the budget just wont stretch that far realistically, so they'll be handbuilt over here.
    Your Past is Not Your Potential...
  • I was seriously impressed with the 303s - they took my bike from really good to superb! (Storck Absolutist). I had to return them to the shop/club but am hoping I can get a good deal on them this spring if they're for sale. Ready to take the plunge. The only minor issue I'll have with them - and this is particular to these wheels - is that they're a fiddle to swap around due to the Firecrest rims being seriously wide - so when they're on, they're on.

    Interesting point from Ugo re tape Vs. glue. I'll keep that in mind. I lost 600g off my wheels when I tried them out and noticed it pretty strikingly.
  • sungod
    sungod Posts: 16,522
    Bigpikle wrote:
    <...>
    I'm not sure whether to go for a 38/50mm combo or the full 50/50mm as an all-round set though.
    <...>

    deep rims can get hairy, especially if you're a light rider or if the bike is light - i remember kicking hard to crest a hill and accelerate down, turned out there was a strong crosswind near the top, as i took off over a dip in the road the bike blew sideways out from under me, big wobble! that was with 53/53

    in still conditions, or with a direct headwind, there's probably little in it for 38 vs 50, the difference becomes more significant as the wind angle changes, then 50 may have less drag, but it'll also catch sidewinds more

    i'd go with the 38/50 for a more versatile set
    my bike - faster than god's and twice as shiny
  • Monty Dog
    Monty Dog Posts: 20,614
    I've ridden carbon tubulars for racing for over 10 years in all conditions. For dry conditions, nothing quite beats the feel of a decent tubular like a Corsa CX. In the wet, particularly on steep descents you do need to plan ahead, scrubbing off the water from the rim before progressively applying the brakes - I have also found deep, lying water good for scrubbing- off speed! I've never had a pinch puncture with tubulars but have cracked a couple of carbon rims. Finally, there's plenty of evidence of alu carbon clinchers, particularly with latex tubes overheating and blowing out on long descents due to the poor heat dissipation of the rim.
    Make mine an Italian, with Campagnolo on the side..
  • Gigantex Carbon Clichers 50mm for Majorca, or, kysrium Elites?

    Dont think I can carry both