Rounded derailleur hanger bolts

Today I was removing my rear derailleur hangar to try and stop an incessant creak. However, the bolts were very hard to slacken which surprised me as I didn't think they would be overly tight. Out of the three bolts I only managed to slacken one with a 2.5 mm allen key. The other two feel as if the allen key is rounded. I have tried a 3mm and it's far too big for the hole and a T10 torx is not touching it either. Any suggestions? Or is it drill the bolt and use an EZ-out?


  • aberdeen_lune
    aberdeen_lune Posts: 547
    Drill it out. Had to do that the other week. Once I put the new hanger on I had to use the hanger alignment tool. Think the force of drilling pushed the chainstay/seat stay out of position a bit.
  • requiem
    requiem Posts: 57
    I've had the same issue in the past. I ended up dousing with wd40 in an effort to have some soak in to the threads (having left it overnight) and then gently tapping in the appropriate sized torx bit with a soft mallet. This did the trick for me. Hope that helps!
  • david7m
    david7m Posts: 636
    Have you tried a drill slow in reverse? It might grip it enough to loosen it.