CityCyclingEdinburgh Forum » Questions/Support/Help

Rear mech thread size

(12 posts)
  • Started 11 years ago by kaputnik
  • Latest reply from chdot
  • This topic is resolved

  1. kaputnik
    Moderator

    Slightly obscure topic - thread size for rear mech hangers. I've got a modern (2008 Giant) frame and a modern (2012 SRAM Rival) rear derailleur. Both should have compatible threads for the hanger, right?

    Wrong (it seems). The derailleur has begun to strip the threads on the hanger, so I've stopped trying to install it before I cause any catastrophic damage. The frame was new old stock and there's no previous damage to the threads (bike has never been assembled anyway).

    All my googling has turned up is that rear mechs should have a 10mm x 1mm thread / pitch known as "M10 superfine" in the thread industry.

    I've never had any trouble like this, derailleurs have always just "worked" when I've put them on the frame.

    Posted 11 years ago #

  2. Roibeard
    Member

    Without insult to your competency, I've found that the angle to present the derailleur to the hanger hasn't always been obvious, so getting them properly started took a few attempts.

    No doubt a proper mechanic will be along shortly with the correct answer, though!

    Robert

    Posted 11 years ago #

  3. Cyclops
    Member

    All modern hangers have a 10mm x 1mm thread as have all rear mechs. Possibly a frame aged +40 years might have something different but definitely not nowadays. Is your rear mech hangar slightly bent as this can sometimes cause problems with cross-threading? If it's not an interchangeable hangar very occasionally these may need the threads chased on new frames before fitting the rear mech.

    Posted 11 years ago #

  4. kaputnik
    Moderator

    Thanks chaps. It's a frame made from pencils, with a threaded metal insert. I stopped trying to tighten when I was getting resistance so think I've only b******d the first mm or so of threads and it should be fine once a tap of correct size has been run through it. There shouldn't be any bend in it, as it's not metal and also never had a mech in it.

    Posted 11 years ago #

  5. kaputnik
    Moderator

    All sorted thanks, running the correct sized tap through it sorted it out. The frame is carbon and aluminium composite and wrapped in a sort of plastic sheath, some of the plastic had got into the threads I think meaning the dérailleur was screwing in at an off-angle and beginning to strip the threads. No harm done.

    Posted 11 years ago #

  6. Uberuce
    Member

    Tap?

    Also, on a scale of one to ten, how much should I know that already?

    Posted 11 years ago #

  7. gembo
    Member

    Tap is DIY term I believe linked to the thread for a screw? Applies to bikes if you have a thread that needs realigned, may work on this forum too. ChDot could give the thread a Tap to get it back on topic?

    Posted 11 years ago #

  8. Smudge
    Member

    A tap is an engineers tool used to cut a screw thread in a blank hole, it can also be used to clean up a slightly damaged thread. Often found as part of a "tap and die" set, one lot of tools for internal threads, one for external threads. Very handy things (if you ever have the correct size to hand for the piece you are working on... sigh)

    No real reason for you to know the term unless you've had cause to use them or it's come up in general conversation. As you hang around with bikie types I'd give it a 2 out of 10 ;-)

    Posted 11 years ago #

  9. wingpig
    Member

    I think Dalry Lidl still had some tap and die sets in stock last week from their most recent budget tool extravaganza.

    Posted 11 years ago #

  10. chdot
    Admin

    http://citycyclingedinburgh.info/bbpress/topic.php?id=2052

    Posted 11 years ago #

  11. Focus
    Member

    I've only had cause to fit a rear mech twice that I can remember, but any time I'm screwing in a tricky thread, I always turn the screw in the opposite direction until I hear a click to tell me the screw is seated correctly. It saves an awful lot of cross-threaded screws!

    Posted 11 years ago #

  12. chdot
    Admin

    "I always turn the screw in the opposite direction until I hear a click"

    Sound advice.

    Posted 11 years ago #

RSS feed for this topic

Reply

You must log in to post.


Video embedded using Easy Video Embed plugin