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Bottom bracket sizing

mswmsw Posts: 313
edited June 2010 in Workshop
Hi all,

I've picked up an old Gazelle road bike from 1984/85 on ebay and am gradually finding out which bits need replacing/fixing. The latest thing to crop up is that when having it resprayed the bottom bracket turned out to be seized and had to be cut out, so now I need a replacement - but I can't find out much good information on sizing. The old one was a Shimano BB-UN10, but even Sheldon Brown's site doesn't have much (any?) info on this model.

t's a Stronglight double crankset, but beyond that I can't find out much about what type of replacement would fit. I'm pretty confident it's an "English" thread, but what about all the other measurements? Does anyone have any recommendations of models?

Thanks in advance
"We're not holding up traffic. We are traffic."

Posts

  • mswmsw Posts: 313
    Just to clarify - my question is really how important the other measurements are, not what the measurements of my specific ex-bottom bracket were!

    Assuming I get the diameter and threading right, will any new bottom bracket fit OK?
    "We're not holding up traffic. We are traffic."
  • Monty DogMonty Dog Posts: 20,614
    Firstly, it'll be English / BS threaded, but need to know the model of Stronglight chainset to be sure of the right length of spindle. FWIW 'old' i.e. French Stronglight chainsets feature ISO taper. Generally most double chainsets of that era with straight arms require a BB of 113-115mm. More recent Stronglight chainsets are in fact made by Sugino in Japan and feature a JIS taper and length can vary due to model. You can mix and match but you need to compensate in length for the differing types - often it's just a case of trial and error in fitting one. A piccie of the chainset will help considerably. Any modern cartridge BB or the right length / thread will be suitable.
    Make mine an Italian, with Campagnolo on the side..
  • mswmsw Posts: 313
    That is brilliant, thanks Monty Dog. The chainset's one of these:

    http://www.velobase.com/ViewSingleCompo ... 5&AbsPos=5
    "We're not holding up traffic. We are traffic."
  • 2tired2ride2tired2ride Posts: 285
    Can I also ask about BB sizing, I took a Cottered Crank off a mates bike with a 113mm BB and I'm putting on a http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWNX:IT will it still need a 113mm BB?

    I dont want to steal this thread, but I didn't want to start a new one with this so similar to mine.
    "If we all had hardtails we'd all go down the hill, just slower"
    Nick Larsen


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  • Monty DogMonty Dog Posts: 20,614
    msw wrote:
    That is brilliant, thanks Monty Dog. The chainset's one of these:

    http://www.velobase.com/ViewSingleCompo ... 5&AbsPos=5

    Your cranks are a French model and remain by my estimate that you'll need a ISO taper 115mm - but until you fit it and measure the chainline, can't be certain.
    Make mine an Italian, with Campagnolo on the side..
  • Monty DogMonty Dog Posts: 20,614
    Can I also ask about BB sizing, I took a Cottered Crank off a mates bike with a 113mm BB and I'm putting on a http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWNX:IT will it still need a 113mm BB?

    I dont want to steal this thread, but I didn't want to start a new one with this so similar to mine.

    The ebay list specs a 119mm - you may be able to get away with a 113mm, but it depends on your frame clearances and what chainline distance you need - this is more critical if running singlespeed.
    Make mine an Italian, with Campagnolo on the side..
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