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Old 11-15-04, 08:06 PM   #1
sorebutt
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Front brakes vibrate - help..

My road bike developed a problem with braking.. When I am at 15-20 Mph, and press on the brakes, the wheel starts to vibrate as is if had ABS on my bike, quite violently.. When I look at the wheel while it is vibrating I can see it shaking up/down or back/forth.. I feels like the rims have areas where the brake pads do not grab, but I cleaned the rim, and changed pads (koolstop salmon) but to no avail..
At higher speed (30mph) I do not feel the vibration...

The wheel is true, and round, I also made sure it doesn't have a bulge in the rim...

The brakes are Campy Centaur '04, originally with stock pads, and now with Koolstop Salmon.


any idea what's going on?

Thanks in advance..
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Old 11-15-04, 08:10 PM   #2
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Is your hub maybe loose?
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Old 11-15-04, 08:28 PM   #3
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Is the toe-in on the pads set right?
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Old 11-15-04, 08:55 PM   #4
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Still sounds like the rim may have a problem. Sometimes the join area where the rim is put together
will get a little off and give the brakes something to grab. One way to rule out the wheel is to borrow
some ones front wheel and ride it and see if the problem is duplicated. If not then the rim is the cause and probably should be replaced. If so then the brakes or headset may be the problem. Steve
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Old 11-16-04, 12:50 AM   #5
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Your pads may be glazed and/or your rims may be dirty. Clean the rims with alcohol and a Scotchbrite pad. Use some medium or fine grit sandpaper on the pads to knock the shineyness off.
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Old 11-16-04, 01:26 AM   #6
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I was thinkin' the hub..lift the front wheel off the ground -spin and hit it it. If it vibrates the bolts\ hub may be loose (tighten in small increments, you can crush the bearings into the races).

The headset as somebody posted should be checked as the fork\ stem should not shift inside the headset...and can, and will vibrate @ different terrain, speed.
(try a wiggle test?)

Dunno.
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Old 11-16-04, 11:49 AM   #7
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I have a Mountain Bike that has the same problem. It always has. (for 3000 miles) Ht the front brakes and it shakes like mad. Through all of it's shaking, i have had a new headset put in, new pads, cleaned rims many times and it still shakes.

I am used to it now, but think i need to investigate. Hmmmmmmmm.?
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Old 11-16-04, 03:40 PM   #8
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Follow-up:
I have taken the tire off, an measured the rim all around and it is uniformly 19.5mm I tightened the brake calipers to the fork and reinstalled the brake shoes, realigned them by the book, used a scotch bright pad soaked with alcohol to clean the rim all around.
I will have to wait till tomorrow to see if it worked, and I'll let y'all know..

Thanks for the help..

Last edited by sorebutt; 11-16-04 at 05:19 PM.
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Old 11-16-04, 03:53 PM   #9
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Quote:
Originally Posted by Ranger
I have a Mountain Bike that has the same problem. It always has. (for 3000 miles) Ht the front brakes and it shakes like mad. Through all of it's shaking, i have had a new headset put in, new pads, cleaned rims many times and it still shakes.

I am used to it now, but think i need to investigate. Hmmmmmmmm.?
Borrow somebody's wheels and see if that stops the vibration. Looks like you've tried about everything except replacing the wheels.
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Old 11-17-04, 07:52 AM   #10
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If you can look down and see wheel movement you have a loose bearing.
Either axle or headset.
Enjoy
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Old 11-17-04, 01:57 PM   #11
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My bike does that. I think I need more toe-in. The headset and axle bearings are not loose.
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