I bought an old frame from craigslist. I assumed that it was Italian from the info he gave me, the fact it is incredibly lightweight and the really fancy lugs. It was sandblasted and all of the decals and badges were removed. The only identifying marks on the frame were the serial number on the bottom bracket: x33478, and the on remaining bottom bracket cup which had, T.D.C. Made in England, stamped to the side of it.Jumping ahead of schedule, I ordered an Italian bottom bracket (the previous owner measured the BB to 70 mm). When it got here I tried to put it in. Evidently it is not 70 mm (bummer). So I was playing around with it and found out that both bottom bracket cups are left hand thread. I repeat, BOTH BOTTOM BRACKET CUPS ARE LEFT HAND THREAD (not the BB I bought, but the threading on the frame).Sheldon Brown has offered no help on the subject, neither has bike forums, so I am turning to you, Yahoo Answers. Can you help me? What kind of bottom bracket do I need?
This is a long question but bear with me. You are not going to like this. Not at all. There are just 2 possibilities and either one demands that the frame be scrapped. 1) You may have a frame with a Whitworth threaded bottom bracket. The thing here is that they are nowhere near the diameter of any modern unit so the (slim) possibility of being able to retap the bottom bracket is gone. For some reason that I can't get my head around there were a couple of factories that preferred both cups left hand, others that did both cups right hand, and some that did one right/one left BUT it was all Whitworth; 2) There were some bikes made slightly behind the Iron Curtain, in Poland, the Czech Republic, East Germany, and West Germany that had a 2 piece cottered crank. The drive side cup was put in the frame with the bearing surfaces facing out, the crank put through, and the remaining cup installed. These were LH on both sides as well and I have no idea what the threads were- I just know they don't accept anything else. As time went on and the cotterless crank became more the standard, enterprising individuals found other bikes, pulled the old crank and drive side cup out, then refitted with a cup from the donor bike and used a new spindle. I am not aware of those bikes EVER having a factory installed cotterless crank. Like much of this early technology it was quickly overtaken as the Japanese Revolution took over and became more of a standard product. I can only suggest one thing- go to a well equipped shop and ask them to try and chase the threads. Some shops will refuse due to the high cost of the tool, and I would personally refuse because it was already attempted in my shop and failed along with the destruction of a $150 tap.
