Nukeproof generator rear hub end capnukeproof end caps are available for the generator 3 in 1 hub so you have the option to choose the axle system that fits your bike this allows easy conversion between all major axle sizes qr 135mm x 12mm or 142 x 12mm features qr 135mm x 12mm 142 x 12mmbuynukeprooffrom chain reaction cycles the worlds largest online bike store