A local riderhad a somewhat horrific accident a while back that has been suggested to have been caused by the failure of his brake pads (for carbon rims) against his aluminum training rims which he was riding at the time.
While several of the local bike shops have suggested that it is fine to leave your carbon wheel brake pads on when you switch back and forth between your aluminum training rims and your carbon race wheels, the brake pads mfg websites appear to be mostly silent on the topic.
I seached the forum but its seems to be mostly “opinions” out there…
Any industry types out there with real understanding of the functionality and risks of leaving the brake pads on with aluminum rims ?
Carbon pads are typically made out of a softer, grippier compound so that they are more effective on a carbon rim (which is typically slicker than aluminum) so it would reason that the opposite is true. If anything, a carbon brake pad should provide a bit MORE stopping power on aluminum rims.
Was it a “sudden” failure? Possibly a brake cable slipping through a pinch bolt that wasn’t properly tightened?
I have left my break pads the same for 7+yrs and have had no issues
Granted my front Alps is alu but my disc is carbon
If the rider in question breaks a lot the pads may have become
to smooth to have a good breaking surface after extended use
I have changed the pads 3 times in 7 yrs
.
I was told that carbon brake pads tend to pick up shards of metal when used on aluminum rims and that these shards can damage the carbon rims, when you put them back on.
Right, but the danger would be that the combination of soft material and more grip on an aluminum rim could tear the pad apart, or fail as it heats up.
its important to remember also that someone whose “never had a problem” in say… Houston TX is not the same as never having a problem descending huge alpine mountains.
everything always works great until it doesn’t =)
If anything, a carbon brake pad should provide a bit MORE stopping power on aluminum rims.
The issue with pads is that carbon does not dissipate heat (at all) so that unlike an aluminum rim, which absorbs and dissipates the heat generated by the pad/rim friction, on a carbon rim the heat is concentrated in the pad and they deteriorate ( in some cases they have been known to melt, which doesn’t offer a lot of braking power).
My understanding is that the pads (which were in reasonable shape) failed to engage on the alu rim.
What brand of carbon pads was the rider using? Synthetic, cork, etc.? What were the weather conditions like? How old were the pads? Were the pads “glazed?” Were the aluminum rims clean, or have lot’s of brake “schmutz” on them? If they were recently cleaned, what was used to clean them?
There are a lot of variables in a situation like this… pretty hard to narrow it down to just “the carbon pads did it.” Need more info
I was not trying to infer that “the brake pads did it”…that may end up being for the courts to sort out, and as you note, there are a host of other factors which come into play.
As one of those who switches between my carbon race wheels and my aluminum training wheels, I was hoping for some technical guidance on whether I should be concerned enough to be swapping pads each time, or whether, in the normal course of events, leaving the carbon pads on is safe.
Are the Carbon pads designed to deal with aluminum rims, or are we all just assuming it will be ok.
Heck, I have enough to worry about with traffic, pedestrians, roadworks etc…I don’t want to be doubting my brakes.
I have used cork carbon pads for both with no issues what-so-ever. Personally I have no experience using synthetic carbon pads on alu rims but know many people that have used Swiss-Stop with great success. I think the biggest thing to keep in mind is to make sure that the pads (regardless of type) are not glazed over and your rims are clean and product free.