There is one more unwelcome variable here: how deeply the crank seats onto the spindle. I replaced the conventional BB on my son's Specialized Hard Rock mountain bike with a Shimano UN-72, which messed up his chainline because the (Shimano!) cranks did not seat all the way onto the tapers. I salvaged the situation by moving the UN-72 to my aluminum-framed Ross (73mm vs. 68mm BB shell width), and buying a shorter-spindled UN-72 for the Hard Rock.
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069