I just got a rack to mount on the rear of my bike frame, but I'm puzzled at which mounting holes to use. On the right side of the bike there's an obvious screw hole for mounting, but the corresponding spot on the left side has something in the screw hole so I can't use it. Hopefully you can see the silver obstruction in this picture -- mounting hole would be just above and to the right of the axle.

enter image description here

The other screws are holding on the disc brake, so I don't think I want to mess with them.

The bike is a Trek 3500, the rack is a Blackburn Local Spring Clip.

Looking for advice on how to proceed with mounting this.

  • Is the obstruction a sheared-off rack bolt?
    – Swifty
    Jul 28, 2018 at 16:03
  • Did you verify the rack is disc compatible? many of them are not.
    – mikes
    Jul 28, 2018 at 17:52
  • Yes this rack was specifically purchased for compatibility with discs.
    – bstpierre
    Jul 28, 2018 at 19:39
  • I doubt the obstruction is a sheared-off bolt -- I haven't had any rough rides that would have broken it, and it appears to have a Z on the end of the bolt so I wonder if it is something intentionally installed as part of the ZOOM brake system?
    – bstpierre
    Jul 28, 2018 at 19:40
  • 1
    @Batman so is the answer just "use the long skewer" ? I guess that's just option 2 if I had RTFMd properly. Thanks. (And you should leave that as an answer so I can accept it.)
    – bstpierre
    Jul 29, 2018 at 1:35

1 Answer 1


The quick release skewer is the lower mounting point, remove the skewer pass it through the rack and reinstall. After the lever is tightened, verify that the threaded rod end comes to the edge of the acorn nut. If the threaded rod is not visible you will need to source a longer skewer.

  • The skewer head will not fit in the recess in the rack support. Jul 31, 2018 at 11:25

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