Chainset BB bolts won't refit.

Bunneh Posts: 1,329
edited December 2012 in Workshop
I stripped down my old single speed bike to respray it (done a nice job too, for a newbie at spraying) and on putting it back together I fitted the cranks, and started to put the crank arm bolts in - they won't even start to fasten, it's like the hole's too small and they can't catch the thread. They look like these


I thought I had damaged the thread removing the cranks but it looks fine. I get the feeling there may be yet another tool needed to fit them or has something gone horribly wrong?

Thanks for any help :)


  • Are you sure you have the correct bolt in the correct crank? I suspect one may be right hand thread and one left hand...
  • Monty Dog
    Monty Dog Posts: 20,614
    Crank bolts are regular 8mm metric and are all righthand thread. The thread on the BB axle may be damaged if the bolt threads look OK.
    Make mine an Italian, with Campagnolo on the side..
  • Bunneh
    Bunneh Posts: 1,329
    I feared as much. Wondering if I can somewhat retap the bb axle with another, slightly smaller bolt.
  • nicklouse
    nicklouse Posts: 50,675
    Bunneh wrote:
    I feared as much. Wondering if I can somewhat retap the bb axle with another, slightly smaller bolt.
    a smaller bolt will not work.

    think about it.

    just get a new BB. or run a tap down the thread to clean it out if you have filled with paint and crud as i guess you left it if and did not cover the threads.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Bunneh
    Bunneh Posts: 1,329
    I have a selection of taps here so I'll have a fiddle today whilst the weather's crap. I did cover the threads when I resprayed but I think they may have got damaged when I was using the crank extractor.

    Cheers for the replies :)
  • Yossie
    Yossie Posts: 2,600
    Double check that you have fitted the cranks back on close enough to the b/b - they may be sitting a little way off and therefore the bolts aren't long enough to reach the threads - even a mil or two will be enough to give you a problemo.

    If you have taken off everything off caefully using the correct tools then I'd say that it would be quite difficult to jeff up your b/b threads.

    A gentle tap with a persuader will do the job to bring them closer. Or take them off, smash them with a hammer, chuck them in next door's garden and buy a Ritte instead. Then smash the rest of teh bike up with a hammer and throw that into next door's garden as well.


  • Bunneh
    Bunneh Posts: 1,329
    There was swearing but no throwing over the fence. I thought if I had to get a new BB I may as well try something, so I put in the same sized bolt from something else and started to gently turn it - it went in, was tight but I moved it a bit further. Taking it out I cleaned all the metal slips from the inside and put the other, original bolt in and turned... it worked and went in smoothly!

    Unexpected but it worked! The threads on the other bolt are a little bit wider so I think, and me not knowing sh*t about engineering, it somewhat 'retapped' it a little.

    All good now :)

    I threw a teabag into next door though, as I didn't want to leave them out of the fun.