Running a new pair of carbon clinchers with used brake pads that have previously braked aluminum rims. I wiped the pads off and they stop fine.
Anyone done actual damage to carbon rims by doing this? I like to swap wheels, but not pads. 
Fred
Better off changing them, ive ridden wrong pads a few times. Havent had any overheating problems, but did experience some sketchy braking in the rain. Gotta be able to trust your brakes for that 1 time that you really need them.
Canāt talk about probs but change all. Parts of the alu can stick to the pads and these can damage the carbon.
According to my guy at the lbs, pads that have been on aluminum surfaces collect tiny shards of said aluminum whilst braking. When using those same pads on carbon, the aluminum can now impale itself into the carbon, increasing the rate of wear and tear.
Hereās what I did, I added a second set of brake pad brackets and pads to my tab when I bought race wheels. Then, when I swap wheels, itās just one screw to take out each pad and put the other in. No changing the pads themselves.
I donāt have carbon wheels but have occasionally changed pads for friends, so I donāt really have experience using cork pads.
Is there a special compound for the carbon rims? What would hold someone back from using regular pads for them and then switch them out for another set of regular pads for aluminum rims?
Seriously a set of 4 Jagwire pads are $20 and a set of cork pads is $50.
Edit: a set of Reynolds blue pads can be had for $30
jaretj
I donāt have carbon wheels but have occasionally changed pads for friends, so I donāt really have experience using cork pads.
Is there a special compound for the carbon rims? What would hold someone back from using regular pads for them and then switch them out for another set of regular pads for aluminum rims?
Seriously a set of 4 Jagwire pads are $20 and a set of cork pads is $50.
Edit: a set of Reynolds blue pads can be had for $30
jaretj
Other than the aluminum shards thing, I think the cork is to protect against the rare, but real risk, occurrence of braking really fast. If you are clipping along and need to slam on your brakes (squirrel in the road, car cut you off, hot chick in bikini, etc) the rubbery ones heat up. This can cause the carbon to warp. The cork ones dissipate heat better and wonāt cause hot spots. I donāt know if there are any rubber-type materials recommended for carbon.
Thanks
jaretj
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For a lot of people it is the tedious job of replacing the rear drive side pad, not the cost. In these cases it helps to change the pad bolt to a 8mm head instead of using the standard hex bolt or sawing off the L shaped hex tool to about 3/8 of an inch to provide the necessary
clearance without removing the crank.
I donāt have carbon wheels but have occasionally changed pads for friends, so I donāt really have experience using cork pads.
Is there a special compound for the carbon rims? What would hold someone back from using regular pads for them and then switch them out for another set of regular pads for aluminum rims?
Seriously a set of 4 Jagwire pads are $20 and a set of cork pads is $50.
jaretj
Are you talking about a bike with a hidden rear brake?
The only ones Iāve done have been on the rear triangle.
jaretj
Itās difficult to answer with specific issues as the brake pad material, amount of heavy braking, wet vs dry conditions, carbon surface/ wheel composition etc all contribute.
Hereās a partial list of issues:
- Aluminum shard accumulation. The shards can damage the carbon braking surface. This can be mitigated by removing all large shards manually and sanding the pad surface to expose fresh pad material. Whether thatās more work than just swapping the pads is up to you. I recommend occassionally removing the glaze that most pads get with use even if you arenāt switching wheel material types.
- Pad composition. Pads for aluminum rims are softer than most for carbon. They can wear very fast with long sections of heavy braking. There are tests from 3-4 years ago where a set of pads were completely used up on a long mountain descent with heavy braking. Likewise, most manufacturers have developed, or have specific recommendations, for pads to be used with their wheels. Not using the recommended pads can void any warranty for the wheels.
- Heat Accumulation. This has been an achilles heel for full carbon clinchers for years now. Many manufacturers have changed their resins, construction methods and surface treatments to help with this. Carbon wonāt lose heat as quickly as aluminum and in heavy braking, can excede the resinās glass transition temperature. There have been plenty of photos on the web of carbon clinchers that have been totally damaged this way.
- Wet vs Dry. Carbon braking surfaces have been notorious for poor wet braking performance. Surface treatments for the braking surface and newer pad materials have helped but in most cases, the braking wonāt be as āgoodā as aluminum.
How many of these factors come into play for you, your riding conditions, road topography, braking quantity, pad composition etc is not easily known. If you, like many, are using aluminum wheels for training and carbon for races, change the pads as this doesnāt happen often over a season and itās not a huge thing to do.
How many of
Thanks for all of that. Hopefully that will help the OP as well.
jaretj
Are you talking about a bike with a hidden rear brake?
The only ones Iāve done have been on the rear triangle.
jaretj
Yes, Iām referring to the rear brakes mounted on the chain stay behind the bottom bracket.
I can appreciate the heat build-up from using non-carbon specific pads so will change them for this reason.
Has anyone actually experienced damage from aluminum shards? if so, Iād be curious what this does to the braking surface.
Fred
I stopped swapping pads halfway through the season after I installed TriRig Omega brakes and the job became even more of a PITA. Iāve been using Kool Stop Salmon pads (designed for aluminum rims) with my training wheelset and a front Bontrager Aeolus carbon clincher (my disc wheel rim is Al). After three months of training rides and a few races, Iām likely through with pad changes for good. There are no noticeable changes in the braking surface and brake performance is as crappy as it was with cork pads.
A few caveats: I live in a non-mountainous area, my carbon wheel was cheap, Iām light and my tri bike rides donāt require much braking.