Loose/worn pivots or shock bushing, if you use the saddle to lift the bike off the floor can you feel a clunk or play? If so its the shock bushing
Otherwise turn the bike upside down, take the rear wheel off and unbolt the shock from the rear end and waggle the rear triangle around to feel for play in the pivots
I have an issue with my 2010 Nomad (Alu). There is a noise coming from the bike which sounds like an old oil can. A kind of two stage clunk. It was occurring every time the drive side pedal was put under load at the top of the revolution. I checked the cranks and put new bushes and bearings in the pedals, cleaned the drive train. Seemed ok in the garden!
Next ride out i discovered it is still there. It was occurring whilst pedalling but also with pedals level whilst pumping the trail. There is also an occasional ‘bag of spanners’ loose metal noise from the rear. I think it is either some play in a linkage or my rear hub (superstar switch evo 6 months old), but everything feels tight. Bought the frame about 2 months ago and it had just had a new pro kit fitted by Stif (although the paperwork never materialised!!)
Any opinions or advice as to what the problem may be before I strip it all down?
I have been over everything and all appears correct. I did find that the cassette has gouged the freehub. (XT on superstar switch evo). Could this be the root of the problem? If so, any remedy or is a new freehub required?