Pedal threads - non-standard size
I am trying to get SPD clipless pedals on an old department store bike. The thread pitch is the same, but the diameter of the bores is a hair less. I did not have anything to measure with at the time so I do not know what the size is (I can find out).
My question is if anyone knows if there is a way to adapt pedals to work.
I would be tempted to drill and tap the crank, but from what I saw I don't think a proper size drill bit to cut the larger threads would get down past the original threads to full meat. That, and if I could, I don't have a left handed thread tap that size (I don't have any left handed thread taps period).
Replacing the crank would mean replacing the chain rings also. There again, I don't know what the BB size is. With everything else that's been "odd-ball" sized I would expect the BB to be a strange size also at this point.