I was thinking of upgrading the Bottom Bracket on my bike (68mm 1.37X24 square taper spindle) with a cartridge setup, and my LBS said that it can't be done, but I think they are blowing smoke..... They also said I could no longer find parts for the current BB if it did ever fail, and I would have to throw the bike away. I have found several cartridge type BB's that are 1.37X24 which is standard 68mm English thread, what gives?