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bottom bracket help

mmukmmuk Posts: 398
edited December 2011 in Workshop
I've had a search but could find nothing, so here goes!

I've just bought an old track frame - English, and 68mm, as far as I can measure! - no BB in it and I want to build it to a fixed for road use.

two questions - does it matter what BB i use, and how do I work out the size? - I'm looking at a Stronglight single speed chainset, with a BB that comes in 110, 113, 115, 116, 118, 119, 122, 127 & 131mm available - sealed cartridge.

http://www.ebay.co.uk/itm/Stronglight-A ... 600wt_1037

I believe the distance between the dropouts in important - I make this 116mm

any advice welcome!

cheers

Mike

Posts

  • deswellerdesweller Posts: 5,271
    The spindle length of the bottom bracket is determined by the chainset. There should be some information in the specification of the chainset telling you what spindle length you require.

    You might have to fiddle about with your rear sprocket position too but I don't know much about that.
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  • Monty DogMonty Dog Posts: 20,614
    You should be aiming for a chainline of about 41-42mm, so unless you can find the spec for your chainset, it may be a case of trial and error of fitting one and working it out from there. You can fine-tune the chainline on the rear wheel too by a mm or two either way by reversing the sprocket or fitting a slim spacer - any bigger and you'll need to respace / redish the rear wheel.
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  • HerbsmanHerbsman Posts: 2,029
    You need to choose a bottom bracket axle length that will give you the same chainline as your rear wheel.

    This will help you work it out http://www.sheldonbrown.com/chainline.html
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  • Have a look at the Spa Cycles website and see if you can spot your chainset. For one particular chainset, they spec 107mm BB

    http://www.spacycles.co.uk/products.php ... 0s109p1944
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