This picture shows the inside of my bike hub on the side of the brake. In the centre is a nut thing that holds in the gubbins on the other side, where the rear sprocket is located. It is a hub with internal gears and there is another nut located on the other side (the sprocket-side) which keeps the sprocket and splined-sprocket holder in place, on top of a couple of springs and sets of ball-bearings. My problem is that the gears are not shifting (and the shifter lever is difficult to move) and I'm having trouble determining how tight each nut should be. It moves to the lowest gear easily enough, but if I want it in high gear, I have to keep back-pedaling and going over bumps. Too tight, and it seems to stop the wheel from being able to turn at all, and too loose and the gears stop working. Does anyone have experience with these fickle internal gear systems? It's a SRAM super 7.