Carbon rim braking problem?

[Lister Farrar]

I'm sure it's partly the retrogrouch in me, but this story is scarey.

http://ccforums.ipbhost.com/index.php?showtopic=8589" onclick="window.open(this.href);return false

I seem to recall seeing pro riders fishtailing with grabby brakes on carbon rims in some video clip I saw. Anyone here had a carbon rim braking problem?

[John Guthrie]

Lister, I doubt this has much to do with carbon rims. I succembed to my fantasies this summer and procured a set of Zipp 303 tubulars, which I ran with cork pads on DA 7800 calipers. I was quite prepared for compromised braking, and was surprised to find very little difference. I switch pads when I switch wheels as it only takes minutes, and protects both the rims and the pads. You don't want to ride the brakes, as they do heat up, and I don't run them in the rain. I doubt 99% of the pros would ride carbon rims if there was some catastrophic braking issue.

[Lister Farrar]

Thx John. Were your pads the ones recommended by the rim maker? I wonder if that was his problem. He used something other than what came with the rims.

[John Guthrie]

Lister, here's the scoop from the Zipp site. Of course they recommend their own pads, my LBS did not carry, plus I heard they wear quick. I still think this guy had some mechanical issue...

"From a data point of view, the braking of carbon rims is very specific to the manufacturer, so you will generally be best to do what they recommend. Our silica ceramic surface is actually slightly more agressive than aluminum when dry and about 96% as effective when wet when using the specific Zipp pad. Many rims like those from Corima, Campagnolo and many of the Taiwanese rims have a pure carbon surface at the brake track and you will need to use a cork pad so as not to damage the rim.

The cork pads are soft and have a low coefficient of friction, but will not damage the all carbon surface. For more aggressive braking a stock Shimano or Campy pad can work, but these contain abrasives such as aluminum oxide which can damage a pure carbon surface (aluminum oxide is the stuff they make sand paper from). Campy and Shimano pads will not damage a Zipp rim as our surface is very hard, but the Campy pads specifically are so agressive that they generate excessive heat and can melt, leaving melted brake pad on the rim, which is almost worse than wearing the rim out as the melted pad material can cause brake pulsation and can be very hard to remove.

Our pad is thermally conductive for lower temperatures, and will not melt, so it is very safe for any carbon rim, and works well on aluminum rims. Our pads also will not abrade your aluminum rims making them last longer, but for most any other carbon rim you are really safest to use cork which is completely non-abrasive, but really doesn't work well at all on aluminum rims. "

[Lister Farrar]

Thanks John.

More good info here from a bike shop guy on the Bicycling forums. Essentially, he says that swisstop pads used on aluminum, (say training wheels) may glaze up when used on carbon (such as race wheels). More stuff worth reading too.

http://forums.bicycling.com/eve/forums/ ... 3651037746" onclick="window.open(this.href);return false