Can’t screw in my rear mech. Suggestions?

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  • Can’t screw in my rear mech. Suggestions?
  • Tried to fit a rear mech onto a brand new Cove Handjob frame last night but it just wouldn’t screw in. Looks to me like they’ve gone a bit over the top with the paint and it’s all over the threads in the frame. Anybody got any suggestions as to what to do? Would a little bit of paint stripper work? Would a bike shop be able to sort it out, with something like a re-tapping of the thread?


    As you suggested – common tool in a decent bike shop. Other thing you could do is try and screw the mech in from the other side to clear the thread. The paint may be a bit thinner on the inside. Done this myself to good effect.

    Get an old long bolt the correct size, put a nut on it, cut slots along the thread, file a taper on the end, take the nut off to clean the thread and you have a home made tap that should do the job – wind it in the hole half a turn in quarter back. Needs a bit of mechanical sympathy to avoid ruining the thread

    Tried the screwing in from the other side. I get so far and then it won’t go any further. Rarely use bike shops, so wasn’t sure whether they would have a tool for the job or not.

    “mechanical sympathy” – that’s that option out then!

    M10x1 iirc, not a standard pitch for a 10mm bolt, so you’d be unlikely to have one lying around. Any decent bike shops will have one, quite a common thing to have to do.


    Had the very same problem on my new handjob frame and just took it inot the bike shop and they did it for me for nowt in a minute or two.

    Goldenwonder, are you saying that a standard M10 tap won’t do the job properly? Someone I work with has offered to lend me one but from what you say, it’s not a standard thread for a rear mech?

    Premier Icon jonathan

    Rear mech is 10×1 (which is “M10 fine” I think), “normal” M10 would be 10×1.25 (“coarse”)… I think!

    A threaded rear axle (say from a shimano QR rear hub) will be 10×1 as well – which would make a good basis for a homemade tap. And also a homemade hanger straighter apparently 🙂

    Sorry, just to clear this up, in idiot terms, if I’m going to go down the route of tapping it myself, I would need a M10 x 1 tap. An M10 x 1.25 tap would be no good?

    Premier Icon jonathan

    No – that’s quite a big difference to cope with I’d have thought. But no personal experience.

    I’ve only ever need to use a stiff wire brush to clear those threads before, but I guess it depends on the paint.

    You can’t use a standard M10 tap, at the pitch of the thread isn’t the same, you’ll need to make sure the tap is M10x1, 1mm pitch instead of the standard M10 which is 1.25. Whereabouts are you? If you’re anywhere near the midlands I’ll gladly do it for you.

    Cheers for all the help guys. It makes sense now. Goldenwonder, thanks very much for the offer but I’m stuck out in the arse end of nowhere, in Norfolk. Looks like I’ll have to try and find a shop that’ll do it for me.

    Or depending of how quickly you need it doing, take the hanger off & send that up to me to sort.

    Steel frame with non-replacable mech hanger, but thanks again!

    Bugger, course it is, serves me right for not reading what the frame was!

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