Carbon wheel braking performance

I know back in the beginning of carbon wheels braking performance was considerably worse than alloy brake tracks.

I’m looking at sorting out some deeper wheels which are mostly carbon options, my local wheel builder said that the braking is as good as alloy these days.

Is this true, with the appropriate carbon pads and 105 calipers?

They won’t be winter wheels I’ll keep my alloys for that, and could change brakes if ultegra or Dura ace are more powerful.

While not like 105… moving from alloy rims and giant pads to carbon rims and swiss stops significantly increased my braking force with the TRPs on my propel. There’s actually now so much braking force that under medium to hard braking I can feel the TRP arms being bent forward!

I ride 5800 brake with normal shimano R55C4 pads. At least for me with my rims, it bakes good. Maybe my Ultegra bakes with alloy rims bake a bit better, but the difference not very significant.
Of course it also depend on the braking surface of the rims

Dry braking is really good nowadays. Braking while wet on the other hand leaves much to be desired and on some rims, the first attempt to brake while wet is quite butt clenching. Carbon rim brake clinchers will always have the flaw that the resins they use have to be able to deal with the heat. Whether that’s an issue for you, depends on what you plan on using them for.

105 brakes should be no problem. A good (swissstop black prince) or recommended brake pad for the rim is the way to go.

agreed that dry braking is fairly good, although still not as good as alloy.

I have zipp with the showstopper and enve with whatever their latest brake track is called and there a few downsides (FWIW I only use the approved manufacturer pads - so the swissstop ones might be better/different)

1 - in the wet, nowhere near as good performance

2 - they don’t modulate as well, especially the zipp - which does a little “grab” as you apply a lot of force in a hurry - way less feel.

3 - they wear pads really quickly, again the zipps in particularly - and they are $$$expensive$$$. I can get away with many thousands of km on alloy wheels and probably around only 1000km on zipp ones - and I’m only around 74kg.

4 - the enve in particular are really noisy - like a jet engine. You may or may not mind this but what is very annoying is that when they flex (or the frame flexes) under power and you can hear the brake track touching the pads at the rear. I have to run my pads really open on these to minimise it - but I still get it on big efforts,

just my experience

I’ve found braking on my carbon rims to be essentially the same as alloy in the dry. Close enough to not notice it. However, as others have said, they’re pretty bad in the wet. It’s okay if you’re approaching a corner and planning on slowing down, but I’d hate to have to brake suddenly for a car or something, and as such I leave the carbon wheels at home when it’s wet.

As for 105 vs Ultegra/DA brakes. I noticed a big difference in shift quality when I went from 105 to DA, but the brakes I couldn’t tell a difference. Well, braking is a little nicer overall because the levers are a bit more solidly built, but I swapped the callipers later on and didn’t notice any change from just those.

I have had two races in the wet, and most of athletes (a lot of whom had carbon rims) seemed very hesitant to push it on the downhills. That was an advantage for me (as I was on disc brakes). Regarding 105 vs. Ultegra, I don’t think this will make a huge difference on the brake end of things, but the levers are nicer.

Very expensive carbon rims with specially textured rim brake surfaces tend to be better at holding up in the wet, but they start “singing” when you brake. I don’t care, quite the contrary, it gives me an auditory indication of how close and fast they are on group rides. But to others who prefer their bike to be completely silent that may be something to think about.

I never minded my Reynolds carbon rim brakes until descending Col du Glandon last month. That wasn’t fun and on future trips to Alps I will bring alloy wheels. In upstate NY with some decent hills I like the carbon rims just fine but I also don’t race or even ride much at all in the rain.

I never minded my Reynolds carbon rim brakes until descending Col du Glandon last month. That wasn’t fun and on future trips to Alps I will bring alloy wheels.

What wasn’t fun about it? Was it wet? I have Reynolds wheels, and find them fine in the dry, but haven’t ridden big mountains on them. I don’t ride them loads in the wet, but when I do I find them OK, provided you have the opportunity to brake early to wipe off the surface layer of water from the rims. Unexpected / emergency braking in the wet would not be great, as others have mentioned - there’s a second or two of delay before anything much happens!

In the dry I don’t find much difference between alloy and carbon although I use more pads with carbon (Swiss stop), In the wet it takes a few seconds for the brake to bite. I took alloy for this years marmotte although it was sunny. I wouldn’t be happy going off those descents if it was chucking it down with carbon. I have seen Mavic carbon wheels recently that have a serrated braking section but it looked really aggressive and think you would go through pads in no time. Like everything, I believe the higher end carbon wheels are better for braking but can vary from lesser priced carbon wheels.

A few things made it not fun -

The slope, extended duration of the descent, and repeated hairpins that limited how much speed I was comfortable carrying through turns all made it very difficult - to the point that I was stopping regularly to ensure I let the rims cool, and by end of day, my hands were pretty tired. I am around 165 lbs. for what it’s worth. I was using GP5000TL - so no risk about tube failure, but still, I felt I had to be a lot more cautious than I would have on alloy wheels. Also, it was dry - if it was wet, I can’t imagine how bad it would have been. Wheels are recent reynolds assaults with their required blue cryostop pads. Maybe higher end might be better, but these aren’t no-name or out of date wheels.

A bike rental shop I used in the past also mentioned they stopped renting with carbon rim brakes this year after having quite a few rims fail last season due to extreme heat on the braking. A giant shop, so all tubeless - they weren’t tube failures, but rim failures. I can absolutely imagine overweight and inexperienced cyclo-tourists absolutely demolishing wheels/brakes riding down that kind of terrain.

But again - I’m talking about it being a problem specifically for descending hairpin HC climbs in the Alps… for most all other uses, I’ve been really happy with them. Outside of the hairpin sections, I found they were fine on most of the other stuff I rode over the month. So I will still ride them 90% of the time here in NY - but will bring a pair of alloys next time I take my bike to France :slight_smile:

Also, agree that the wet braking issue is normally not a huge deal other than the delay. But I really wouldn’t have wanted anything more working against me on those alpine descents than I already had.

I’ve used that exact combo, great wheels but I agree — zoomin’ downhill/hairpin braking is terrifying.

I would use again in a closed course race but not for open road riding.

If I’m honest, I’ve not really had any issues with carbon rims and braking once used to it. For those having problems on long alpine descents, I wonder how much of it is due to the rider than the rims? I’d imagine the rims that fail are often ridden by guys dragging the brakes all the way down the mountain.

First hairpin descent I did was down Tiede through Vilaflor. I let the guide know I was nervous about the descent (more so than the climb), and I got a 10 min tutorial on how to get down the mountain when I was at the top. Those 10 mins made it one of the most fun experiences I’ve ever had on the bike! Got down the mountain pretty quickly, on a hire bike with carbon rims and no overheating problems. Now coming down from Cap Formentor in the wet on alloy rims - THAT was terrifying!!!

I managed to cook a front carbon rim in the pouring rain going down some 15-20% grades last year.

Luckily, warranty covered it and replaced the rim.

In the dry, carbon rims are fine to brake on. In the wet, they can be down right scary when there’s the 2-3 seconds when you apply them and nothing happens then they start to bite.

Think the main thing is to not drag them all the way down the descents. Be off them, then apply them hard as you come to the corner. Easier said than done when wet or in traffic!

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Riding carbon totally changed the way I brake. As quoted, I now brake late and hard, and even later and harder w/ alu rims! Lots of free speed to be had with proper braking technique.

But carbon is still kinda sketchy esp in non-race road conditions — pedestrians, cars, stop lights, etc.

I’d indeed bet that is the cause of many failures on rented bikes. Still amazed it happens that often! Nonetheless, when you start getting past 8% for extended periods, coupled with sharp turns, you’re really getting beyond practical and enjoyable use of such rims. Which is pretty consistent with all the feedback here.

Saw another poster saying no problem on Tiede after a they took a quick clinic - I’m not at all surprised. That’s a very mild descent and wouldn’t expect to have to do much braking. I wouldn’t be worried about carbon rims on it at all. They were a blast on all the 6-8% climbs in the alps, particularly the more sweeping sections.

It really depends what you plan to ride - but just a few km of 10-12% descending can not only take the fun out of it, but become quite dangerous - I can’t even imagine how not fun it would be if caught by surprise in the rain on such terrain. If you stick to gentler grades, they’ll be fun.

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Have you looked into the Dura Ace carbon wheels that have the aluminum brake track?

I have an eBay saved search for them! Getting a bit rare these days.

Think I’ll have to get some similar ones built when I get the cash.

These are the ones that I got last year I think