The nature of BB sizing and compatibility is definitely a black art. For one thing, there are "standards," the manufacturing tolerances for which actually may produce articles whose sizes might overlap, in terms of "bigger" or "smaller." For example, Sutherland's notes that the JIS standard spindle end is 12.65 mm, but where that's measured is not specified (you can't measure right on the end of the spindle, which is generally chamfered). ISO standard, in Sutherland's Appendix, is 12.6 mm measured 1.5 mm from the end of the spindle plus 0.02 mm, minus 0.05 mm. Sutherland's betrays a bit of frustration itself:



So, Campagnolo fits somewhere between ISO (smaller) and JIS (larger). And that's not all Campagnolo, apparently. Phil Wood said (more on this later) that if you had a crank pre-1994, it took Phil's JIS taper, while 1994 and later take the "Campagnolo = ISO" taper.

http://www.philwood.com/index/2008%20Catalog.pdf see page 14 -- it't not in their FAQ for some reason. That page also has the three tapers shown side-by-side. I defy cudak888 to tell them apart visually if we cut off the top part of the photo.

Phil Wood is also a bit strange in that they recommend using a small amount of lubricant on the spindles, saying something like "our tapers are designed for that."

From all this, I infer that Campagnolo changed from their own proprietary taper to the somewhat smaller ISO taper in 1994, meaning that if you get a newer Campagnolo BB, it should provide the right taper for an ISO-sized crank. The problem is finding a longer one that doesn't cost $200.

Given manufacturing tolerances, it's a wonder that anyone can get a decent chainline. Sheldon Brown said that the difference between chainline produced by an ISO and JIS taper is about 4.5 mm. On a 20-degree taper, that translates to 0.16 mm difference in the size of the spindle end. And that is approximately (but a little more than) the difference I measure between a TA spindle, a couple JIS, with a Campagnolo falling between them.