This build didn't get finished for BO12. To top it off photobucket ate my photos, so I had to deal with re-uploading them all. With a little luck I can get it finished this time. This is where I left off.
I've started on the rear section of the frame. I think once I can get the frame finished things will start moving faster. It took several tries of getting everything square and then having something move before I was able to get it tacked in place. If you're wondering, yes that's a piece of head tube that I'm using as a bottom bracket. I'm not really sure why, it's what I had on hand. These old bikes had small diameter bottom brackets so I didn't want to use a 51mm ID shell.
Here are the seatstays ready to go in. They have a very slight taper at the top which should look nice.
These match the inside diameter of the stays, they will be the internal lugs to strengthen the joint.
Not exactly. That is the next hurdle. My plan is to make my own bottom bracket. I have a straight piece of pedal shaft from a moped and a pair of cottered cranks. The funny thing is that I can get sealed bearings that fit the bb, but are like 1.5mm too large for the pedal shaft, or bearings that fit the pedal shaft which are 5mm too large for the bb.
Good luck on your bearing search. That was the first thought that came to my mind, ^ ala bikewhorder...fitting the cranks to your custom BB.
The press fit sealed bearing idea is a good one. I had a Fisher mtb from 1989, when Gary first produced this type of BB. I made a tool out of a piece of threaded pipe to install / replace the bearings. Primitive, but it worked.
Here's a pdf of the Fisher catalog from 1992. Might be some info you could use in the spec sheets.
The headset cups will fit, but headset inner races are 1" ID, quite a bit larger than most crank spindles. My plan right now is to use tubing that fits over the OD of the bb shell. That should give me the extra 5mm I need for the sealed bearings to fit and wont require a special spindle.
The fork is done. I welded it up and pinned it at the top and the bottom. I also got the top of the seat stays capped off, and cleaned up the inside of the bottom bracket. Time is running out, so I'm trying to get the big stuff taken care of. On to the crank.