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Hi All! Please help with advice. I was doing some regular brush cleaning on my new Diamond Mission Pro bike that I purchased off the diamondback website (less then month old). A little bolt near rear axle that screws into the frame just fell off under my brush when I felt it was loose and touched it with my hand…

Should I try to replace anything under the warranty?

Thanks a lot in advance!enter image description here

  • This is a warranty repair if the bike is only a month old. Don't loose the end. Don't try and repair it yourself either. This would be a nasty wee job without a proper workshop.
    – Criggie
    Jun 6, 2018 at 9:42
  • @Criggie not sure about the "proper workshop", but depending on dropout construction it's probably possible to unscrew the dropout, pop the axle nut to the inner side and unscrew the broken bolt from inside using thin pliers. Jun 6, 2018 at 9:59
  • @Klaster_1 if it is a through-hole then the job is much better. If its a blind hole then the fix will involve an extractor and drilling, or complete replacement of the frame as last resort. Cheap bolts are no saving.
    – Criggie
    Jun 6, 2018 at 19:03

2 Answers 2


This bolt is used to hold the nut on Shimano E-Thru rear axles, it's usually a part of rear derailleur hanger or drive side dropout. I think it prevents the nut from rotating and the fact that it snapped off might be a symptom of loose rear wheel axle. Sections of recess around the bolt without paint might be where it touched the frame.

If you still have the frame/bike under warranty, I advise to contact the place you purchased it from. Even if the issue comes down to user error (loose axle), they will probably help to extract the remaining bolt section and source a replacement.

Alternatively, you can just make a slot for flat screwdriver and use the leftover as a grub screw (that's what my dropout uses, for example) or unthread it and use any suitable bolt instead.

  • 2
    Another reason for getting it done under warranty is getting a recorded and documented history. If the bike turns out to be a lemon then you need that history to prove your case with the manufacturer, not just the LBS/reseller.
    – Criggie
    Jun 6, 2018 at 9:45

As mentioned in comments and others answers you should take it to the bike store you purchased it from and see if they will do a repair under warranty. However, they might refuse as they only have your word that you applied very little torque to the bolt.

What will be needed to extract the bolt is a stud extractor. Basically a hole is drilled in the bolt and a what looks like a tapered reverse threaded bolt is screwed in, which then screws the bolt out.

If you have a drill and appropriately small bits you could do it yourself, but it's a tricky operation as the extractors can break, especially ones for a small bolt like this. As others have said, probably best to let the bike repair shop tackle it.

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