Full Suspension and Gears for novice setup....

marts500
marts500 Posts: 85
edited January 2011 in MTB workshop & tech
Trying to set up my 1st FS mtb,the rear mech works perfectly on the workstand but as soon as i nip out for a test ride the mech is a total nightmare and won't even drop down onto top gear.Is this because the movement of the rear triangle is pulling the cable...?
The cable is slung underneath the BB....should the outer cable there have a big loop and do rear suspension movements often cause this trouble...?
How should ths be set up...?
Its a specialized FSR frame with a fox shock.

cheers
FS Newbie