Results 1 to 3 of 3
  1. #1
    mtbr member
    Reputation: jonw9's Avatar
    Join Date
    Jun 2009
    Posts
    720

    Fork Post Mount Bolt Length?

    I am putting a set of Hayes Strokers on my bike, and reading through the installation guide I read the following:

    Mount the caliper to the frame or mount bracket using (2) M6 x 1.0 18.4mm long mount bolts and (2) mount washers. Snug the bolts, but leave them loose enough so
    that caliper will move on its slots.
    Caution: For post mount forks you will need to use (2) M6 x 1.0 22mm long mount bolts. These bolts are supplied in your aftermarket kit or supplied from the bike
    manufacture. Failure to use the longer bolt may result in fork damage that will not allow you to tighten down your caliper properly.
    Now they included (4) of the 18.4mm bolts, but not any 22mm. I am not understanding why the 18.4mm is enough to work on an IS adapter, but "Not allow you to tighten down your caliper properly"

    Is it really that the 18.4mm doesn't have enough thread engagement?

    Is this something I really should be concerned about? Will the 3.5mm make a difference between my caliper shearing off and flying into my spokes?

    NOTE: This is with a 160mm rotor, so the caliper will be directly mounted to the fork posts, no adapter.

  2. #2
    mtbr member
    Reputation: Scoobyvroom's Avatar
    Join Date
    Mar 2011
    Posts
    10
    Yes it will make a difference. If you tried to torque the 18.4s with only a couple threads of engagement you stand a very high chance of pulling the thread out of the hole. The thread you mentioned is a M6x1mm so that is 3.5 more threads of engagement. That is a lot and the torque spec for that bolt to yield the threads is a calculated number base on the properties of the bolt and the material on which it is being thread into. I'd try to get the longer ones..

  3. #3
    mtbr member
    Reputation: jonw9's Avatar
    Join Date
    Jun 2009
    Posts
    720
    Quote Originally Posted by Scoobyvroom
    Yes it will make a difference. If you tried to torque the 18.4s with only a couple threads of engagement you stand a very high chance of pulling the thread out of the hole. The thread you mentioned is a M6x1mm so that is 3.5 more threads of engagement. That is a lot and the torque spec for that bolt to yield the threads is a calculated number base on the properties of the bolt and the material on which it is being thread into. I'd try to get the longer ones..

    Thanks, I contacted Hayes about the same issue, and they are sending me out a pair of the longer bolts. I will just wait for those. I am anxious to get things installed.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •