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I have the Canondale F5 with the Avid Juicy 3 brake system fitted to the bike front and rear. The bike is over a year old and hasnt been ridden hard just on the road for communiting in the summer months.
I have a problem with the rear brake whereby you get alot of vibration when the brake is applied. I have tried bleeding the brake and replacing the pads, i have also tried to align the caliper to the disc with the caliper bolts loose, squeezing the brakes and then retightening but the vibration is still there.
When the brake is gradually applied the vibration shakes the bike and isn't really effectiving slowing the bike until you get to the point where the wheel locks up. I have enough power in the brake to easily lock the wheel but i dont have any intermediate braking ability so they are either off or wheel is locked up.
Is anyone able to give me any ideas to what may be causing the problem?
It's not the wavy rotors is it?
My elixir rear on my scandal started doing it too - resonates through the frame, really annoying and not solved it yet
Juicy 3 brakes come stock with organic brake pads
what pads did you replace the stock pads with?
also, which Avid rotor do you have - G2 or G3?
the G2 could lead to vibration on certain setups, the G3 tends to reduce this characteristic
copper slip on backs of pads??
Try swapping the front and rear rotors to see if it goes away. If it does and the front feels fine, stick with it, otherwise, try and scrub the rotor with a few high speed, fast stops and, if that fails, buy a new rotor.
Vibes tend to occur where the pads have gripped and slipped on the rotor, usually because the pads have been able to move relative to the rotor, either due to the caliper flexing on its mount or when the pads are worn and the pistons are further out of the caliper than usual. It can be started by worn pads but won't always be fixed by new ones.
Hi Guys, many thanks for all your good comments, I just thought I'd let you know the outcome!
It seemed most people were suggesting the rotor so I took a closer look, I fired a plumb laser on the leading edge and gradually turned the wheel, the rotor was straight as a dye - or so i thought!!!
I then tried a gauge which measures to the 1000th of an inch and found that there was a bow in the rotor of 3000th of an inch (0.0762mm); I flexed it back into position so it was within 1000th of an inch (0.0254mm) across the total perimeter of the rotor.
Put the wheel back on and tested in out, not a vibration to be felt.
I am absolutely amazed that the rotor would have to be this accurate so no wonder every time I visually looked at it, it seemed in perfect alignment.
I am also amazed with how easy the rotor was to flex back into the right position so I'm now very paranoid about knocking the rotor and ending up with the same problem but for now it works perfectly.
Thanks again to you all for taking the time to comment.
I have a boardman team hybred with juicy 3 brakes and have the same vibration problem on the rear. In the wet the problem seems to disappear, but dont want to have to go out only in the rain !! I will check the rotor and hopefully sort it out without buying any new kit. the brakes have the original pads, has anyone repalced them with any better pads, I'm headingto Alpe DHuez to watch the tour in July and want to be able to stop at the bottom without every one thinking I have just run over a turkey.