Originally Posted by
rustymetal
There's a 300 lb or so difference between me and the other rider.
Not to be indelicate (I'm a big guy myself) but what you're saying is that when the bike has a ~400lb rider, it pulls right, but with a ~100lb rider, it doesn't? I'm guessing that the bike was not designed for such a rider. The weight may be distorting the frame.
Originally Posted by
rustymetal
There's no need for a string, I have a park frame gauge that can measure offset across the headtube and seat tube back to the rear dropouts on each side. The thing is dead on that way.
Again, this is in the spirit of helping with the problem: Is the alignment preserved when you get on the bike? Your chalk test kind of indicates that the alignment is preserved. Going back to what others have said: How is the fork alignment? Is the fork alignment preserved when you are on the bike?
Originally Posted by
rustymetal
This is a fillet brazed frame, with stamped rear lugs. Very similar to a Schwinn frame of that period.
I'm quibbling here (but I'm an engineer, so that's my hobby), but I suspect not fillet brazed. First, most Schwinn bikes were welded in the 1940s (see ad
here). Looking at pics of 1940s Columbias, it looks like they used welded frames, too. Fillet brazing is a very expensive method of joining frames, as it's slow and requires great skill. Schwinn did do a lot of of it, but only for the higher end bikes (later in the "Xtra Lite" (spelling?) class of bikes like my Superior, or the Schwinn Paramount tandems. The later low-end Schwinns (like the Varsity I had) were make of steel strip that was rolled and welded into tubes or stamped into headset halves and welded. The stampings for the headset and bottom bracket had tapers stamped in to mimic fillets. I don't think that Columbia ever used headset stampings. (Could be wrong, if so, post a pic!)
Originally Posted by
rustymetal
have a Park FT-4 fork jig, FFS-2 frame straightener, an ***-2 gauge, and FFG-2 dropout alignment tools, plus an Eldi frame holder and an HTS-1 head tube straightener. Plus I've got various other custom bending tools that fit into the BB shell, seat tube, and head tube to measure and bend if needed via hydraulic force.
Holy cow, that's some great kit!