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I'm confused re bottom bracket, advise needed.

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I'm confused re bottom bracket, advise needed.

Old 05-28-13, 03:57 PM
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howieleem
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I'm confused re bottom bracket, advise needed.

I have a old British frame that i am building up into a single speed bike. I only have the frame nothing else. The bottom frame width is 68mm so it is probably British std thread.
I assumed that i should buy a bottom bracket to fit a 68mm wide frame, and then get a crankset to fit onto the bottom bracket tapered ends.
The shop told me i need to get the crankset first and this will decide which bottom bracket to get.
I dont understand, as far as i understand the crankset is a crank on one side and a toothed gear and crank on the other, so what dimension of the crankset determines the bottom bracket ??
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Old 05-28-13, 04:04 PM
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Nagrom_
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Cranksets dictate what spindle length to use. It's as simple as that. Your crankset has a mated spindle length. Should be in the paper work.
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Old 05-28-13, 04:16 PM
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Thanks i think i understand now. Some cranksets have a concave gear and some are not, which affects the chainline. All clear now.
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Old 05-28-13, 04:20 PM
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Old 05-28-13, 04:24 PM
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The spider has different levels of concave, which affects the chainline.
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Old 05-28-13, 04:39 PM
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That's hardly the only factor, but sure.
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Old 05-28-13, 05:21 PM
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