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bottom bracket spindle

Old 07-30-18, 01:32 PM
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pillows_
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bottom bracket spindle

Hey folks, newbie here.

My brother gave me an old 96 Gary Fisher Wahoo that needs a new bottom bracket. Checking the factory specs it says I need a 73 x 120mm BB. I came across the Shimano UN55-- sizes 73 x 118mm and 73 x 122.5mm but I don't see 120. The 73 x 122.5mm should be okay, right?
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Old 07-31-18, 05:56 AM
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dsbrantjr
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The 122.5mm spindle will put the chainrings and pedals 1.25mm (~0.050") farther out than a 120mm one. The 118mm will put them 1mm closer. Which works better for you?
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Old 07-31-18, 06:52 AM
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Originally Posted by dsbrantjr View Post
The 122.5mm spindle will put the chainrings and pedals 1.25mm (~0.050") farther out than a 120mm one. The 118mm will put them 1mm closer. Which works better for you?
The above is perfectly correct but you can also buy BB spacer rings to move the BB axle out, just google it & you will understand. But only one.
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Old 07-31-18, 06:58 AM
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Ah, I see. Im not sure which would be better. I ride road bikes so maybe the 118mm? Might not be a huge difference either way.

edit: Bike tinker man-- thanks, I'll look into that if I run into any issues using the 118.

Thank you, gentleman

Last edited by pillows_; 07-31-18 at 07:03 AM.
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Old 07-31-18, 09:46 AM
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Before you go any farther with this make sure that the crank is actually the one that the factory specification says it is. Different cranks can require different length spindles, so if the bike no longer has the original crank(not unusual in a 20+year old bike), the factory spec is useless. Best is to actually measure the spindle length to make sure what you have
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