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BB threads how to tell what it is??

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BB threads how to tell what it is??

Old 04-16-12, 06:33 PM
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thehammerdog
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BB threads how to tell what it is??

I have an old school earlt 80's italian steel grandis roady. How do I tell what tyoe of BB thread I have? I wanted to switchit out to a modern one with new cranks
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Old 04-16-12, 06:48 PM
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It's often marked on the cups, if they're installed on your frame. If not, chances are that the frame is Italian thread. Take a known English thread cup and see if it fits at all. The I.D. of an Italian thread bottom bracket is 36mm, while the O.D. of an English thread cup is just a hair under 35mm (1.375"), so if the frame is Italian the English cup won't even engage the threads.
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Old 04-17-12, 08:28 AM
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Grandis were pretty high end bikes so the crankset thats on there should be pretty decent. Having said that new Italian BB's are easy to find in both older square taper and external bearing cup styles if you plan on using a newer integrated spindle crankset.
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Old 04-17-12, 09:20 AM
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Weird trick: if you can thread an English threaded freewheel hub into it, you have an English threaded BB. Italian BB is bigger.
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Old 04-17-12, 10:40 AM
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Nice trick , thanks.
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