Originally Posted by
Charles Wahl
. . . the one that gives you the right chainline!
You ran out of room with the spindle replacement because the spindle you were substituting has a smaller distance between the bearing tracks than the one that originally worked with the cups you have. TA and Stronglight have quite a wide track; even more than lots of Italian spindles -- look at Sutherland's and you'll see what I mean. Bear in mind that a cartridge bearing BB will have JIS tapers -- a bit chunkier ends than a TA -- so you may need a slightly shorter SER (shell-to-end, right; Sutherland's parlance) than the diagram above suggests. If you can, buy from someplace that will let you return; or have the shop do it.
This is it exactly. The constraints on spindle fitting all have to do with fitting the frame with the intended crankset. The constraints are: the clearance between the chainset (crank arms plus rings and bolts) and the right chainstay, chainline, distance between the bearing tracks, diameter at the base of the spindle end (matching the hole in the cup), and balanced offset between the left and right pedals relative to the frame center plane (the importance of this is a matter of taste).
One of my LBS has a box of old NOS, take-off, and used spindles, including JIS, a Campy or two, some cottered, and the odd Campy or Stronglight, and sells the NOS JIS for $5.00 each. Trial and error is a lot cheaper than with cartridge types.
TAs first may need their proprietary taper, depending on model. If a JIS or ISO allows the crank bolt to seat it properly, you can experiment. First try a spindle that is probably too long, and measure the properties above. Barnett's gives a flow chart for how to match a spindle to a frame and crankset, translating the fit measurements of one example to the closest matching specs for the best available spindle fit. Armed with the part number of your best JIS (if the taper works) fit, you can go to Niagara and buy a Pyramid that has the correct shape.
I think Barnett's or Sutherland's also have a section on Ashtabula dimensions. If so, it may cut out some of the trial and error.
This ain't easy, go carefully.
I asked Peter White about spindle specs for more modern TA cranks (an Alize), and he said finally that if I send him the crank, he can select the best BB for me. Ultimately, having a good BB is worth the cost.