Weird clunking sound at front of bike (but not headset?)

tenori

Hi guys,

I've been reading this site for ages, but only just joined the forums! My bike has started to get this weird "clunk" sound and I'm hoping you guys might be able to point me in the right direction!!

Basically, I get this clunk generally when applying brakes (but not every time) or going over bumps in the road. It doesn't happen when I'm not sitting on the bike - I've tried rocking it back and forward with the brakes on, to check for movement with the headset, and there doesn't seem to be any then. But the moment I sit on the bike, and do the same, you can hear it clunk occasionally (but I can't *feel* it clunking anywhere).

I've tried doing adjusting the headset regardless and tightening it up, but it's about as tight as it will go - not sure whether I could overload the bearings if I make it tooo tight? (but there's still plenty of movement in the front wheel when leaning it side to side).

Any thoughts? What else could I be missing?!

Many thanks!!

James

bicyclepirate

could it be the front wheel hub?

tenori

How would I check? (sorry, still educating myself on the finer details of bike maintenance!).

I've checked that the wheel is definitely securely in its quick release, is true, and the spokes all seem the right tension... are there other things I should check?

thank you!

ynyswen24

With the wheel securely in the dropouts, see if you can rock the rim from side to side. If you can then the hub bearings need adjusting and probably regreasing. Not usually a major job wuth then front hub, a pair of cone spanners should see you good.

andyrr

Either headset or wheel bearings probably.
Wheel - should be no looseness when you try to wobble the wheel rim when grabbed at the top and the wheel is held just off the ground.
Headset - can be hard to spot a small amount of play in this but maybe the headset starnut or expander has crept slightly up the fork steerer and now the top-cap is not pulling the headset up tight enough ?
Also check the STIs are tight on the bars, bars tight in the stem and stem tight on the steerer, brake caliper nut is done up suffficiently tight on the rear of the fork too.

tenori

Thanks everyone, all really helpful!

The wheel itself seems fine so I guess it must be the headset after all. Will have another play - is there any risk of over tightening the top cap in the headset or is it generally ok as long as I'm not getting any stiffness in the steering movement once it's all put back together again?

will3

In the headset there's often a wedge ring that centres the steerer in the top race. I had a clunk under braking that turned out to be due to this ring being under the top race not on top of it. It was kinda hard to see as rocking back and forward didn't really show it up.

it'd be item # 8 on the exploded diagram here, for example:

http://www.canecreek.com/manuals/Headse ... ctions.pdf

rake

bike mileage?
integrated head bearings?
ridden in wet?

andyrr

Top cap shouldn't need to be mega tight - if the 'clunk' is still there after it is tightened well by hand then something else is amiss -
Loosen stem - fork steerer bolts.
Push stem down on the steerer.
Tighten top-cap bolt.
Tighten stem bolts.

Bars should turn with no sign of roughness. There should also be no play evident.
Wear can mean that getting the pari of these is difficult and removing excess play results in over-tightness at some point of the bearing movement.

If the expander / star-nut looks as if it is towards the top of the steerer then see if you can add another slim spacer on the steerer and see if that solves the problem, ie the top-cap is bottoming out.

I've sometimes taken a headset apart and found it a real faff to get it all back together perfectly so the issue re the wedge ring could be it if you've done this.

Shaun20

Just to clarify you don't have front suspension do you? I know this is the road forum but wierder things have happened. If you do have suspension the problem could be there???