Ok, so the back wheel seems to move to much when in gear. If the engine is off and the back wheel is suspended in the air the wheel will roll a significant amount(more than usual). Also when riding and gearing up it seems as if the wheel sometimes skids(on each shift) a bit like the chain is catching it and jerking it fast enough to skid slightly. It is not an issue of bad shifting or loose chain. I think maybe something further inside? Any ideas?