These were recommended by the well known bike expert Sheldon Brown, as a replacement set of calipers for vintage 10 speed bikes that required an extremely long reach caliper to reach the bike rim. FAIL. Due to this calipers overall cheap construction and the very long reach, they did not work. When applied at full force, it took well over 10 feet to stop. With such long arms, it just becomes a physics problem; Not enough torque.I'd recommend restorers to go to a machine shop and have someone make you a set of drop bolts so you can use more modern, better calipers.I can't say as to how these would work on BMX bikes (their original application), but I am guessing by how flimsy they are that they wouldn't work well.