Descending with carbon clincher still an issue?

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riochang
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by riochang

Hi all, just got my canyon aeroad with Reynolds strike slg Carbon wheelset.

It's my first time riding on full carbon clincher and I remember hearing people saying bad things about overheating/melting/delaminating etc when carbon clinchers started to appear few years ago.

Has the technology moved on? What do you guys think? I did a few descending test ride (5-12deg descent, max speed before braking ~60kph) with good braking techniques (not dragging on brakes etc) and so far so good. However I am a bit worried what would happen when weather starts to warm up in a few months time... Should I have faith in them?


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Calnago
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by Calnago

2010 was the worst year for carbon clinchers. Both ENVE (EDGE back then) and Reynolds experimented with getting as light as they could and went overboard. The following year they both added material back to their wheels. Since then, resins have been improved substantially and maybe even more importantly brake pads have improved hugely over what you could get back then. I liked the idea of carbon but did not like the clinchers and moved to tubulars after a bad experience or two. Never looked back. However, today I think there are some very fine carbon clinchers but like most things, use common sense. The forces that caused issues with carbon clinchers back then are still present today, but at least manufacturers are dealing with them better and for the most part I think they're pretty reliable. But if you're 200lbs and regularly descending technical mountain passes with a lot of braking, I may want to think a bit more about your choices. But sounds like you're aware of the issues, have good technique, and the wheels are from a reputable manufacturer so I'd say yes, you should have faith in them. Also, back in 2010, everyone was using SwissStop Yellow's for their carbon rims. Ugh! The new pads today are just so much better, and since you're using Reynolds wheels, I presume you're using their blue Cryo pads as well. They work well. Just use common sense.
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bungis
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by bungis

Rider weight and rim depth are still major variables that should be noted afaik. The latter acts as a heat sink away from the brake track due to more material.

Weight?

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Calnago
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by Calnago

Rider weight is of course an important variable in choosing any component or frame, but I don't think the heat sink issue with carbon really applies as much, does it? The fact that carbon does NOT dissipate heat very well at all is where a lot of the problems arise from in the first place. Aluminum, on the other hand, is a very good conductor of heat, but not a very good material for a higher profile rim due to the added weight compared to carbon. And that's about all I know about that stuff before I start talking out of my ass :).
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mpulsiv
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by mpulsiv

riochang wrote:Hi all, just got my canyon aeroad with Reynolds strike slg Carbon wheelset.

It's my first time riding on full carbon clincher and I remember hearing people saying bad things about overheating/melting/delaminating etc when carbon clinchers started to appear few years ago.

Has the technology moved on? What do you guys think? I did a few descending test ride (5-12deg descent, max speed before braking ~60kph) with good braking techniques (not dragging on brakes etc) and so far so good. However I am a bit worried what would happen when weather starts to warm up in a few months time... Should I have faith in them?


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The question is - how long is your typical descent? Even if you drag your brakes.
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spookyload
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by spookyload

Reynolds CtG braking is amazing at staying cool when you use their cryo pads. Being careful on descents is never a bad idea regardless of carbon or aluminum rims. I have a 12 mile climb/descent down Sandia Peak I ride very often. Never had an issue on my Reynolds Assaults or Zipp 303 wheels. Like I said, use the brand specific pad since they are often designed together

Derf
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by Derf

Calnago wrote:Rider weight is of course an important variable in choosing any component or frame, but I don't think the heat sink issue with carbon really applies as much, does it? The fact that carbon does NOT dissipate heat very well at all is where a lot of the problems arise from in the first place. Aluminum, on the other hand, is a very good conductor of heat, but not a very good material for a higher profile rim due to the added weight compared to carbon. And that's about all I know about that stuff before I start talking out of my ass :).


Haven't paid too much attention to the heat conductivity of CFRP, but it's going to be heavily dependent on the "RP" part of the equation, and I'm sure certain epoxies are better here.

http://www.christinedemerchant.com/carb ... ivity.html

Dissipation and conductivity are two different things, too. Fortunately, we generally have our wheels in an airstream, so getting the heat from the surface into the air is less of a problem than getting the heat from the brake track out to the surface (and spreading it over a larger area to augment heat loss)

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rmerka
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by rmerka

Rode my 2015 Reynolds Attacks in the rain this past weekend and found them quite impressive in the wet. Have to echo what spookyload is saying about the wheels with the cryo pads, they stay quite cool even with heavy braking on exceptionally steep roads. I'm very comfortable with them and I'm no light weight...

riochang
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by riochang

I weight 68kg. My typical descent is 10-15km. Using Reynolds cryo pads.
The reason that I wanted to hear your opinions was because the braking technique I used was short hard braking then release for 5-10sec then short hard braking again, repeat. Hoping to let air cool the rims but sometimes there were just too many steep hairpin corners and it was inevitable that I had to apply both brakes for much longer period in order to really slow down my speed. And this is the part that worries me most


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danbjpa
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Location: Brasil

by danbjpa

I'm a 'stiff arm' to descent/corners (noob, fearful) and brake almost during entire descent to don't win speed (tighten and loosen the brake as far as possible to trying don't heating the rims). First time on mountains of my life was in Italy with 'combo of death', a Carbon clincher (DTswiss) + Ciamillo ZeroG(!!) + Corima red cork pads... and lucked I and the wheels survived descend Passo Sella, Giau, Campolongo, Pordoi, Falzarego, Gardena and ride in Granfondo Pinarello also.
I confess that i was afraid because a friend destroy same wheels year ago on L'tape - His technique of descent is only brake hard near the corners.
I weight 47-48kg, maybe my weight was a good factor because I read here that my technique of brake is the best way if you want 'explode' a carbon clincher. lol
I think that I don't repeat this again.

Marin
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by Marin

The faster you go, the better for your wheels. Why? Because then you will dissipate most of your kinetic energy via air resistance.

Long descents are usually not a problem, short steep ones where you have to stop at the bottom for traffic are the worst.

Brake early and hard, and once you reach a manageable speed, use the brakes alternately. Take care to open the brakes fully in between, never drag them.

Marin
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by Marin

Here's a -700m descent where I would have been very close to a KOM (2nd or 3rd place) if a car hadn't held me up. 38mm carbon clinchers.

-> 10th place https://www.strava.com/segments/7813593?filter=overall

It's -9% average(!) with about 15 hairpins. The only time I was really worried about the rims was when I had to stay close behind the car to prepare for the overtake...

kulivontot
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by kulivontot

Every year or so somebody on this forum posts a horror story about their personal experience of carbon clinchers exploding or melting to the point where the rim deforms. Then it instantly devolves into an exercise of victim blaming and polarizing opinions on whether or not it's the rim's fault. The fact that it is discussed perpetually seems to indicate that it can still be a problem, but there is obviously a wide variance between manufacturer to manufacturer and rider to rider. I think getting a consensus will be difficult.
I personally am not really interested in carbon clinchers, but that has more to do with the fact that alloy clinchers are comparably light up until 30mm or so and I am too light to descend with deep rims confidently without getting blown around. But to each his own.

riochang
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by riochang

Marin wrote:Here's a -700m descent where I would have been very close to a KOM (2nd or 3rd place) if a car hadn't held me up. 38mm carbon clinchers.

-> 10th place https://www.strava.com/segments/7813593?filter=overall

It's -9% average(!) with about 15 hairpins. The only time I was really worried about the rims was when I had to stay close behind the car to prepare for the overtake...


What wheelset were you using for this descent?

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fromtrektocolnago
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Joined: Sat Dec 07, 2013 10:15 pm

by fromtrektocolnago

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