Unbalanced Wheels? Grabby Brakes?

Gavin Gilbert

I have a pair of OEM 50mm carbon clinchers from my local racing outlet. I've been using these off and on (mostly off) for the past year on my #2 road bike.

The reason they mostly stay in the garage is that the braking is exceptionally grabby. Feather the calipers and I get a scary modulation from the front - huge amounts of vibration at best and severe shaking if I'm trying to stop from a decent speed.

The rear is also a bit unbalanced. Pick up the back of the bike, spin the cranks and it's a battle to stop the rear end bobbing up and down.

I've had both wheels in a jig and they are true. A very slight wobble on the front but nothing worse than other wheelsets. The shop have cleaning the alloy braking strip with their magic Mavic block, and this helped for all of 200 metres.

I've run Eurus on the same bike without problems. I've run the carbon rims on the Omega and the shaking was replicated. So it's def the wheels and not the bike. I've also changed the brake pads (Campag standard)

Any suggestions as to what the problem could be? And how to cure it?

mrushton

Are you using carbon specific brakepads? You need to use pads specially for carbon rims - Kool Stop are favourites. However,carbon rims are 'grabby' in their nature. Some user on here will poss.have more info

Gavin Gilbert

mrushton wrote:

Are you using carbon specific brakepads? You need to use pads specially for carbon rims - Kool Stop are favourites. However,carbon rims are 'grabby' in their nature. Some user on here will poss.have more info

The wheels have an alloy braking surface - I was under the impression only full carbon rims needed the special pads?

DavidBelcher

Gavin Gilbert wrote:

mrushton wrote:

Are you using carbon specific brakepads? You need to use pads specially for carbon rims - Kool Stop are favourites. However,carbon rims are 'grabby' in their nature. Some user on here will poss.have more info

The wheels have an alloy braking surface - I was under the impression only full carbon rims needed the special pads?

And you'd be right - an alloy braking surface should be fine with ordinary pads. Have you checked the track of the rear wheel? I had speed wobble bother a few years back, because my 8sp (screw-on) wheel had been dished in the way a 7sp one would be! As I had horizontal frame dropouts, I was none the wiser for ages because the wheel could be easily fitted to look as though all was well.

David

phil s

I had the same problem with a set of Halo Mercury 28mm alloy rims I built recently, to the extent that I don't use them and am rebuilding the powertap on Open pros. I tried all combinations of brake pads, feathering, the lot. I just put it down to a weird braking surface.