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Fork shakes when front brake is used

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Fork shakes when front brake is used

Old 02-28-09, 04:04 PM
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RdBike87
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Fork shakes when front brake is used

I just got an old road bike from a friend. A Free-be!
Its a fixer upper and a good project for me.

When I use the front brake the fork shakes A LOT! Its pretty distracting while I'm riding.

I'm pretty new with bikes and their mechanics but I do know how to use a wrench. Haha

What do I have to tighten to get the shakes out of my bike?

Thanks!
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Old 02-28-09, 04:18 PM
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kycycler
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Sounds to me like the head set needs to be rebuilt.
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Old 02-28-09, 04:19 PM
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joejack951
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Probably your headset but also possibly the brake caliper.

The caliper is an easy one to check. Just see if it has noticeable play where it's mounted on the fork. For the headset, the easiest check is to hold the front brake tightly and rock the bike. You should not feel any play between the frame and the fork. Scroll to the bottom of this link for adjustment info: https://www.parktool.com/repair/readhowto.asp?id=127
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Old 02-28-09, 04:53 PM
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gosmsgo
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my guess is that the headset is loose.
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Old 02-28-09, 04:54 PM
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If its a threadless headset than tighten the allen bolt that is right on the top of the headtube.
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Old 02-28-09, 05:05 PM
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Originally Posted by gosmsgo View Post
If its a threadless headset than tighten the allen bolt that is right on the top of the headtube.
...after loosening the stem bolts. Otherwise, you'll just adjust the tension between the cap and stem, whatever that's good for.

If it's old, though, it's probably threaded. There, you need to loosen the lock nut, tighten the adjustable race until the headset is properly tightened, then hold the race in place with a headset wrench while tightening the locknut onto it. Two wrenches are required for proper adjustment.

The question is how long it's been like this. If it's been ridden like that for a while, the headtube can ovalize making the frame scrap.

Check the parktool link:
https://www.parktool.com/repair/readhowto.asp?id=65
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Old 02-28-09, 05:34 PM
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Check the rim for trueness, clean the braking surface.
Before rushing into the headset adjustments, try applying the front brake with the bike stopped, push it back and forth, watching and listening for play. If there is none, loose headset is not the problem.
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Old 02-28-09, 09:46 PM
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norwood
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A loose headset would certainly allow the fork to shake but I'm guessing the actual cause might be extreme chatter from the front brake pads on the rim surface.
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Old 03-01-09, 02:46 AM
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DArthurBrown
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I would recommend starting with the easiest things first. If the sides of the rims are corroded, rusted or in any way not smooth and uniform, it can lead to pulsation, just like disc brakes on a car. The pulsation goes right into the fork.

Clean the rims and take some fine sandpaper to the brake pads to clean them.

If that doesn't work, make sure the headset is tight. Headsets are durable, but can come loose or get corroded/rusted.

If it still shakes, the headset might need to be replaced, or the fork itself might be bent.

If it only shakes when you apply the brakes and not when you go over bumps and such, I would guess that the problem is with the braking surface.
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Old 03-01-09, 03:05 AM
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Panthers007
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Also check the toe-in angles on the pads. Is the front of the pad hitting the rim first, but not at a strong angle? If it's REALLY toed-in so it looks like a 'V' - then moderate this so it just touches first for a brief moment before the rest of the pad catches up and grabs the rim. If it's toed-in backwards (back of pad touches first - change that). Ideally it should hit/grab the rim equally front & back. But most folks prefer a small toe-in in front. This also serves to lessen the brakes from squealing.
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Old 03-01-09, 04:58 AM
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Wiggle everything in the direction its not supposed to go, to see whats loose. The headset turns left to right, so wiggle it front to back. Shouldn't be any movement there. The brakes grip from the sides, wiggle it front to back. The front wheel turns forward. Wiggle it side to side.

Once you find the movement where movement shouldn't be, its easier to diagnose the problem.
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Old 03-01-09, 10:39 AM
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Thank you guys so much for all of the great info!
I have all day to tune it up.
What a great forum.

Thanks Again!
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