I need to know what size chain, stem and bearings to get for a 20" swchinn frame, the catalog shows a 21.1mm and a 22.2mm for the stem, the headset bearings show 22.2x30x27mm, 21.1x32.5x27mm, 22.2x32.5x27mm and the chain has a 1/2"x1/8"x112 and a 1/2"x3/32"x116.