hi i have just bought a shockwave 980 full suspension mountain bike to ride on trails and road the problem i have is the rear suspension it is knocking when i hit a bump like something is loose i have tried the shock soft and ridged but still get a small knock or feeling of something loose when going over a bump etc. could this be the shock ? or loose bearings in the bottom arm ? any advice please. i know its only a cheap bike but this is driving me nuts regards to you all.