Stumpy FSR carbon shock/frame knocking? Help!

kingsfool

Hi All,

Before I go and pester the Concept Store folk I thought I would ask the forum!

I have a Specialized Stumpjumper FSR Comp Carbon 2012. It has developed a loud knocking that appears to originate in the shock mount area over the last year or so. (I understand that carbon frames can really bounce noise around inside).

When you compress the rear suspension there is an audible 'knock' that resonates through the carbon front end with each compression. Say you are riding the bike with the shock set to 'open' and the bike bobs a bit here and there......with each bob comes the 'knock'.

I have taken the whole rear end to bits, had the shock out and serviced under warranty about a year ago, but cannot solve the issue. LBS baffled.

Has anyone come across this? OR does anyone have any ideas?


Many thanks to the Foum!

M

rockmonkeysc

Most likely shock bushes are worn or possibly worn linkage bearings.

kingsfool

You would think so. Had it all apart a couple of times and all seems sweet. No play in bush area or damaged/worn bearings. Thanks anyhow.

rockmonkeysc

The other possibility is a worn pivot bolt. Or maybe a bit of movement in the seatpost.

kingsfool

Thanks again. These parts are also fine. You can physically feel a "thuck" vibration around where the shock mounts the frame. Went for a spin today and it sounds much worse than yesterday....will not be using it anymore until I figure it out.

rockmonkeysc

There only needs to be a micron or two wear in any of those components and the linkage length will exaggerate it a surprising amount.