The following fork tube chart will give you an idea of what your fork tube size is, but the very best thing to do is measure you fork tube Dia. yourself. If you are running clip ons you would mount the clamps lower on the fork tubes, if you run dirt bike bars you may want to mount the clamps higher on the tubes, because fork tubes can taper in and out on some tubes you should measure your tubes at the place you want to install them, this will ensure you get the right fork tube clamps the first time. You can buy a cheap pair of MM calipers at a dollar store. We have 10 different size fork tube brackets: 37mm, 39mm, 41mm, 43mm, 45mm, 46mm, 48mm, 50mm, 52mm, 54mm.