fastfrank

Hello,

Can anyone help me?

I have recently purchased a new mountain bike fitted with the 'Marzocchi MZ comp' suspension forks. I've started to notice a slight knocking felt through the handlebars when I rock the bike back and forth whilst the front brake is depressed.

Initially i thought it was a loose headset as I've expienced this before but reading up on diagnosis tips I can confirm that bit is ok. However testing the forks alone (holding the chrome/painted section of the stantion seperately then trying to bend) I can feel a tiny bit of play.
I assume the leverage from the handlebars just magnifies the play hence what I'm feeling???

As I know jack all about suspension I can't be sure if its fault as such. I spoke to the shop and he said he can take a look but didn't outrightly say there was a problem.

PS. the bike is not fitted with disc brakes.

Comments appreciated.

Many thanks
Frank

Graz

The usual culprit is the headset but it sounds like you have checked this / tightened it up. Check the wheel hub as well for any excessive play.

However there is a high possibility that a bushing or something has worn out in the fork. In fairness to the bike shop without stripping it down it would be hard to say exactly what the problem is. Suspension forks need servicing annually at the very least, assuming you ride regularly. Servicing may also include the replacement of some parts such as bushes that wear out.

Edit: Should have read your post properly, if they're brand new then obviously they shouldn't be loose. May just need something tightening up within them!

dome

If it's that new then get it back to the shop, they'll be able to check it out. If you hadn't checked the headset I'd have guessed it would be that, the headset cups on a frame often settle in when a bike is being 'run in' leading to a slightly loose headset.

Brian

MarkO

It's a classic problem with cheap or lower-mid-range forks. When I worked in the bike shop we used to have it happen all the time with the Suntour forks on Giant XTC4s and Giant Terragos. Basically, what you'll find is that the forks have plastic bushings inside (as has been already mentioned) and they will have either come loose or even cracked. Take the bike back into the shop; it should be < half hour job to strip the forks, re-seat the bushings, and put them together again.

Unfortunately, though, it's likely to happen again if you use the bike seriously off-road, as these forks simply aren't designed to take the kind of hammering that regular off-road riding produces. The only real long-term solution will be to replace the forks with better ones.