73mm. Its an old Raleigh that had their 26tpi. Measured out the BBshell 73mm on the nose. Bought a new 73x110 and then took a worn out 73 that I had and 'retapped' the threads. Basically go in some, back out go in some more, back out. Took like 20-30 minutes but then the new BB went in nice and easy. Don't know why Raleigh would not comply with the 24tpi like the rest of the world until almost the turn of the century.