Have I Fudged the BB?

Discussion in 'Bicycle Mechanics and Repairs' started by MahatmaAndhi, 15 May 2019.

  1. MahatmaAndhi

    MahatmaAndhi Regular

    Location:
    Peterborough, UK
    Hi all,

    I bought a bike online for a project and learning experience and it's a complete bag of rubbish. Example, despite having a 9 speed cassette and Deore rear mech, it has a set of SRAM 3x 5 grip shifters. It is a Frankensteiner, but I'm going to plod away at it anyway.
    I'm currently struggling with the bottom bracket. It's a square tapered threaded one. I went to the non-drive side first. The tool barely fits in the splines, like it's filled with mud or something, but it does turn. In fact, it turns both ways to little or no effect. I've turned it for ages, it just spins but nothing happens. I've watched the drive side whilst turning it and nothing is moving that side. But the drive side is absolutely solid and I can't seem to get a good grip on it (yet - I'll try the bolt and washer trick when I can get to B&Q)

    So the non drive side - is it buggered? If I get a replacement BB, will I still be okay with a new threaded one?

    Thanks.
     
  2. The NDS collar is probably plastic, it’s not unusual for them to flatten their threads. You may find a well aimed chisel will get it out. The Drive side is usually the metal threaded collar, try spraying some penetrating oil in there then have another go. The drive side loosens clockwise. You might need a big long lever to get the torque you need, a monkey wrench with a scaffolding pole over the handle works. You may need a brave assistant for this bit of the job. In order to prevent creaks and cracks the BB does have to be torqued up surprisingly well, this may be the issue, and with a bit of ‘gentle persuasion’ it will come out.
     
    MahatmaAndhi likes this.
  3. I like Skol

    I like Skol Hold my beer and watch this....

    Location:
    Ashton-under-Lyne
    In the case of an inexperienced DIY bodger this might be one for a bike shop mechanic to pass judgement on? It could be just stripped splines or it might be a threaded cup. The experienced spanner monkey will know the difference....
     
    MahatmaAndhi and dave r like this.
  4. OP
    OP
    MahatmaAndhi

    MahatmaAndhi Regular

    Location:
    Peterborough, UK
    I must have looked up and down the various different sections for a repairs area and didn't spot it at all. Couldn't see the wood for the trees, they say.

    I'll have another crack at it tomorrow. If I can't nail it by the weekend, then I'll take it to a shop. But I'm pretty skint, so I'm trying to do the lot on the cheap.
     
  5. C R

    C R Über Member

    Location:
    Worcester
    You appear to have a cartridge bottom bracket, in which case the bolt and washer trick will not be suitable, as the drive side cup will be integral to the bottom bracket.

    If you are struggling to get purchase with the bottom bracket tool, could it be that you have the wrong tool?
     
  6. Ajax Bay

    Ajax Bay Veteran

    Location:
    East Devon
    May be, so attempt the right hand side (metal) (the first comment from @rr says it all). Provided the threads are not damaged (and no reason why they should be), a replacement threaded BB should go in fine. UN55 is the best option: check whether you need a 68mm or 73mm wide one and you'll need to know how long a spindle is required for the current or replacement crankset (eg 113mm).
    I take it you've asked yourself "does the BB actually need replacing?" (at this stage).
     
    C R likes this.
  7. Arjimlad

    Arjimlad Tights of Cydonia

    Location:
    South Glos
    I found popping the tool in the vice & using the frame for leverage works well. A soak with PlusGas is often good before attempting this.
     
    MahatmaAndhi likes this.
  8. OP
    OP
    MahatmaAndhi

    MahatmaAndhi Regular

    Location:
    Peterborough, UK
    The BB is incompatible with the groupset that I bought. The old cheap plastic crank arms fitted to a square tapered BB with integrated spindle, whereas the new (second hand) set has spindle as part of the crankset. So I would say a Hollowtech BB would be the way forward, but I want to remove the old one to ensure that I get the right size.
     
  9. fossyant

    fossyant Ride It Like You Stole It!

    Location:
    South Manchester
    There is a chance the threads in the frame are goosed on the non-drive side (if the cup is plastic then you'll be OK). The drive side should come out with leverage if the non-drive side cup is spinning, but removing that will need cutting. If in doubt - shop.
     
    C R likes this.
  10. Ajax Bay

    Ajax Bay Veteran

    Location:
    East Devon
    If you can get the right hand side out (advice - see above) then however damaged the left hand side one is, it'll come out easily (ime) as removal of the cartridge BB has rendered it just a shell. The very gentlest of cutting may help it out. But there's no doubt your LBS will do this in minutes few, if presented with the frame with the cranks off.
     
    chriscross1966 likes this.
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