Mudguard fitting

Mamil22 Posts: 22
edited December 2012 in Workshop
Hi guy's
Can anyone tell me what size thread is required to fit mudguards to the front and rear brake housings (purchased some Bluemels and bolts are not the correct thread to fit brackets)
Many thanks


  • Anyone have an idea please?
  • Your issue isn't well described but I'll have a go at answering it.

    Road caliper brake threads are M6, canti mounts are M6, frame canti boss studs are M10 (can be either standard or coarse thread), fork canti boss studs are usually M8 (can be either standard or coarse thread), mudguard eyelets are M5 (same as bottle boss bolts).

    If you are trying to attach the mudguard at the fork arch or at the seatstay bridge onto a bike that has road caliper brakes with the recessed Allen nuts then there are three solutions:

    1. Get longer longer recessed nuts or reduce the size of any spacers present so that the recessed nut protrudes outwards enough to hold the mudguard attachment plate;

    2. Modify the recessed nuts by tapping an M6 thread all the way through (the Allen socket sidewalls will have threads cut into them and still work if done correctly). Then attach the mounting plate with an M6 bolt onto the back of the recessed nut piggyback fashion. Search for "Sheldon fender nut" to see what I mean;

    3. Modify the mudguards so that the attachment plates are bolted directly inbetween the brake calipers. This would mean either riveting the attachment plate further along the mudguards or adding metal brackets (shaped like a "U" with square corners) in order to extend their reach.
  • Thanks bikaholic,
    Item #2 is what i was after, I will re- tap to m6 and bolt bracket on from the back (well at least for the front guard)