I have a mid-60s Schwinn Speedster 3-speed (the pig). I bought it several years ago, cleaned it all up and then just rode it. It's my ride-to-the-train bike, and often a toodle-around-town, ride-to-the-beach bike. It gets ridden in all sorts of weather, and rarely gets any attention. It's been a sturdy pig, but it's time for a refresh. The steel rims are heavy, horrible in the wet, and have lots of chrome flaking off. The shifter cable froze, and it wasn't shifting too well before that, so all I have at the moment is high gear. Plus it weighs, I don't know, 40-45 pounds, I'd guess.
For reasons which are not entirely clear (even to me), I thought I would swap in some different parts, stuff which is more readily available, and lighter to boot (the pig will go on a diet). At this point, I have a three-piece bottom bracket adapter, a Sakae CR crank w/ Sugino 46T chainring, a rear wheel consisting of a Sturmey Archer XRD3 drum brake hub laced to a Sun CR18 rim (650A, I believe - guess I should figure that out before I search for tires), and a second CR18 rim I intend to lace up to the existing front hub. I also have enough spare MAFAC Racer caliper bits to make up a caliper to replace the old Schwinn Approved Weinmann brake on the front of the bike.
So, onward. I tossed the bike up on the stand and squirted some Liquid Wrench on screws and nuts (it's pretty rusty), then started to contemplate my rear wheel. The XRD3 hub is spaced at 126mm, and doesn't look like it can go much narrower. The rear end of the bike is spaced at 110mm, typical for those bikes. So, I will have to cold set the rear triangle. I doubt that will be too difficult. The rear cog will move out roughly 8mm, though I can flip it to fiddle with the chainline. This means I will either have to ditch the chain guard or do a little creative bending. I'll try the latter, but resort to the former if necessary.
My first obvious problem will be to figure out a suitable bottom bracket axle. Since I'm tossing the Ashtabula crank, I won't even have that as a reference point. I have a couple cartridge bottom brackets (103mm & 118mm axles). I think the 103 will be the best place to start, but I might have to dredge up a 107 or 110. I think the 118 will be much too long.
Pix