Bottom Brackets

Decent bearings are vital in a bottom bracket - it takes a lot of punishment.

A word on tapers - ISO or JIS?

Not all square taper crank and bottom bracket combinations are compatible. Although nearly all spindles use a 2 degree taper, there are two competing standards for the thickness of the end of the spindle. The JIS (Japanese Industry Standard) size is used by Shimano and most other Asian manufacturers. The ISO (International Standard) size is primarily used by Campagnolo and other European manufacturers.

The overall length of the spindle has no bearing on crank compatibility but does affect frame clearance, chainline, and 'Q factor'. As a general rule, it's better not to mix ISO and JIS components.