Vibrating front wheel

Rockbottom

Rockbottom

Active Member
Been having trouble with my front wheel vibrating and shaking alot when braking at fast speeds. Wondering where the problem could be coming from? The rotor is not bent and the rim seems to be straight (tru'd it as best as I could). Anything else that would cause such noticable vibrations? Wheel is on a 9mm quick release.
 
There are many factors and a few things that could be wrong. Is it a suspension or rigid fork? Does this happen under all braking, or just when braking in a turn? If it's the later, then thru axles can definitely help a bit with stiffness. Outside of the wheel/rotor truing, these are some of the things I'd check from my own experiences:
  1. Loose headset/blown headset bearings. Hold your front brake while holding your right hand on the headset below the bars and rock the bike back and forth. If feel some play, this could be your problem.
  2. Contaminated rotor/pads, or Avid rotors in my experience. The pads can catch in some spots and release in others due to oil or other contaminantes causing inconsistent braking. Brake clean will take any of that off, just don't spray it all over your bike or calipers since it can and will damage at least your clearcoat. Remove the pads and hold a towel or something behind the rotor you're spraying and then wipe clean. If the rotors are polished smooth from long use, you can lightly take a brillo pad to the braking surface in outwards strokes, perpendicular to the braking surface as well as clean up the pads lightly on some sand paper. Regarding Avid, I had a set of Cleansweeps that always shuddered no matter what I tried. I think it was just due to the design of the cooling ports and possible catching on the pads leading edge. If all the parts are too worn, it's time for some goodies anyway, just keep everything clean when you're installing them.
  3. The fork itself. On a suspension fork, blown fork bushings in the legs will cause a similar feel to a blown headset. This happened to me on an old fork and I never knew what it was until I stopped over at Hilltop Bicycles in Summit. You can check this in a similar way to the headset, but it's a little bit more difficult to feel. Smaller fork stanchion diamaters will also flex more under braking load than larger ones.
When in doubt, see Jim @ Hilltop.
 
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I can't be certain, but it seems like its just the wheel is vibrating.

The fork is a fox talas suspension. 2010, so I guess you can say its fairly old. The shaking seems to bee happening under all braking, at higher speeds. (low speeds like turning into a switchback I don't notice any shaking.)

Might be a loose headset, I'll have to check to see if there is any play when I hold the front brake. My guess is it may be a blown fork bushings in the legs as you mentioned.

Brakes are Maugura Marta SL. Might be time to replace the pads either way. I used the light sand paper trick not to long ago when I had some non-stop brake squeal.

Thanks so much for all the info, much appreciated.
 
On top of what 1sh0t mentioned , any chance that the front tire is just skipping when you brake hard? Is the problem repeatable under these same variables or only during the same spot on a trail?
 
Can you swap out with another wheel to see if it makes a difference? This will help narrow down your problem.
 
It's been happening for the past few rides on different types of conditions/locations, mostly I brake at a higher rate of speed.

Headset seems to be tight and secure, I didn't notice any play/movement.

Good idea with swaping wheels, will have to try that. Just have a feeling the issue is prob my fork.
 
Rotors straight? Calipers parallel to rotors at the bad? Fork brake post need to be re faced?
 
This could be a hub issue as well - possibly just needing service. Have no idea what type of hub we are dealing with here. Clearly swapping the wheel will eliminate the hub in the process. But, you can also try this to see if there is play in the axle/hub. From the side of the bike, grab the top of the wheel and try to move it toward/away from you (aka side to side between the fork). If there is play that way, you could have a hub issue. This could be as simple as a lose QR or maybe a bit more complex requiring an overhaul. If you have cone wrenches, this is not a hard job...especially on a front wheel. Park Tool website can be helpful. http://www.parktool.com/blog/repair-help/

If you don't figure it out soon, just take it to the shop. What may be challenging for you to diagnose will likely be figured out in short order by a pro. Further, "web diagnosis" can be a very slow and ineffective process.

Good luck.
 
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