I have seen and read a few posts about this topic. However the part needed always seems to be out of stock. It is for example a TruVative BB032 conversion kit. Can anyone provide more up to date information. I am trying to convert a 10-15 year old Sears bike with a single piece crank to a three piece crank. The chain ring teeth presently seem to be poor quality, although some experts suggest that the appearance is normal. I want to have more freedom to buy modern chain rings as I have been unable to find a double chain ring replacement for the existing Ashtabula type system. The bottom bracket 68 mm long and about 50 mm internal diameter. Will appreciate any help I can get.