If you really want a clamp on brake, Roedale Precision makes them. They are a German company and most of their stuff is metric. Looks like they have clamp ons for muzzle diameters of 20, 21, 21.5, and 22mm. That translates to about 0.787, 0.827, 0.846, and 0.866 inches. There may be others who make clamp on brakes as well.