Join Date: Aug 2005
Location: Pittsburgh, PA
Bikes: '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
Mentioned: 7 Post(s)
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Quoted: 233 Post(s)
The degree of taper (2°) is the same for JIS (Shimano and most others) and ISO (Campy mostly) spindles but the starting dimension is not. ISO tapers start at a slightly smaller width. However, the manufacturing tolerances in the bb and cranks often allow them to be used interchanably if the demands aren't too high.
Theoretically, it's a bad idea. Practically, it often works ok. That said, buy the right bb.