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Gear Question

Where can I find the spec's on the BB of...

Posted on

Where can I find the spec's on the BB of my BRIDGESTONE 400, so I can upgrade to the newer outside bearing BB?

Responded on

Generally speaking, basically you need the size of the bb shell on the frame-68mm or 70mm. That will give you the thread size-68mm for english and 70mm italian. There are several ways to determine bb: 1)Remove the BB currently on the bike and it may have specs on it. 2)Measure the shell size (width) on your frame with a caliper (68 or 70mm). 3)99% of the time english bb are threaded opposite each other (one side-the non-drive side-tightens/loosens normally and the other side-drive side-tightens/loosens opposite) while italian bb are threaded normal (right-tight/left loose) on both sides. 4)Try a spare bb in english thread, if it works it's english, if the threads fall through, it's italian. 5)Italian is much rarer than english, but that is more nowadays. If going to external bb you may need a new crankset as well though-your old crank may not have a long enough spindle. Check here: http://sheldonbrown.com/gloss_bo-z.html#bottom.