After reading the stuff on RR I am keeping the white gears on for the moment. The mesh is quite tight on all the gears. There's no backlash at all on the gears in the tail case so no need for the shims as yet. The front gear was a tight mesh due I think to not using the stock frames (I am using the bright yellow Fusuno frames) so I ground just a tiny bit off the backside of the holes in the frames for the tail unit so there's some room for adjustment. All round the mesh is on the tight side so I hope they'll bed in a bit. I might post something on RR for an opinion on that.