Advertise on Bikeforums.net



User Tag List

Results 1 to 7 of 7
  1. #1
    Senior Member
    Join Date
    Jul 2006
    Posts
    375
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    V-Brake Bosses - Avid v-brakes don't fit???

    I have two bikes from the same manufacturer, and originally both bikes had the same brake model fitted.
    On bike #1, I upgraded to some Avid SD Ultimate v-brakes and used them for some time.

    Now I want to move those Avid v-brakes to bike #2...
    However, when I tried to fit them, it is painfully obvious that they will not fit those v-brake bosses.
    But they fit bike #1 just fine.

    It is not a question of "use a block of wood and hit it with a hammer"... while I do not own a caliper measuring tool, it is clear that the brakes do not even begin to fit onto the bosses.

    So are there subtle variations in v-brake boss sizes??? Is it a question of one size vs. another, or is it just production variances or different boss manufacturers?

    Am I likely to be able to take the bike to my LBS and have them install slightly smaller ones.
    (alternatively I guess I could just hand them the brakes & bike and pay them to "Make it work"... )

    I think someone would have to file down the existing bosses if they are going to work. Or maybe use a heat gun to heat up the v-brake barrel and THEN use a block of wood & hammer + lube!

    Anyway, I would certainly appreciate your advice. Thanks!

    PS. bosses on both bikes are clean, lightly greased, free of paint, etc etc.

  2. #2
    Senior Member
    Join Date
    Mar 2008
    Posts
    3,925
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Never come across that particular problem myself, so I don't know how much help I can offer.
    Some frames/forks (particularly those who also have disc brake mounts and Al frames) have removable bosses. It's an easy thing to look for, so start there.

    Otherwise, grinding down the bosses should work. I've never seen a brake pivot directly against the brake boss, there's always been a bushing pressed into the arm that deals with the actual movement, so you wouldn't have to try for a perfect surface if you decide to go that route.

  3. #3
    cs1
    cs1 is offline
    Senior Member cs1's Avatar
    Join Date
    Feb 2004
    Location
    Clev Oh
    My Bikes
    Specialized, Schwinn
    Posts
    6,130
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Not that it makes any difference now, but what make and model are the frames?

    Tim
    1999 Waterford RSE-11, 1995 Waterford 1200, 1989 Specialized Rockhopper Comp
    1989 Raleigh Technium, 1989 Schwinn Traveler, 1986 Specialized Rockhopper
    1984 Specialized Stumpjumper, 1986 Specialized Stumpjumper and just way too many projects to list.

  4. #4
    Senior Member
    Join Date
    Jul 2006
    Posts
    375
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by cs1 View Post
    Not that it makes any difference now, but what make and model are the frames?

    Tim
    Hi Tim,

    They are actually folding bikes - made by Dahon.
    I've dropped a note on the company's technical forum also
    (Helios P8 ~ fits, Speed P8 ~ doesn't fit)

    dabac is correct that there is a bushing of sorts in the Avid SD brakes.
    So there does not need to be rotation of the brake around the boss, but rather around the bushing.
    I just need to get the darn thing fitted somehow...

  5. #5
    Banned
    Join Date
    Dec 2004
    Posts
    616
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    How much are you missing it by? - is the boss clearly a different diameter, or is it just a matter of a tight fit? I recently had the same problem on an older bike, and in resolving the problem I learned that it is not uncommon for the bosses to mushroom out a bit under the pressure of the fixing bolt compressing in on them. The LBS had a small cutting tool/mill that we fit over the boss and twisted it down the length of the stud -- it mills it back to size. Worked like a charm and the canti arm slid on with no problem.

  6. #6
    Senior Member
    Join Date
    Jul 2006
    Posts
    375
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by ginsoakedboy View Post
    How much are you missing it by? - is the boss clearly a different diameter, or is it just a matter of a tight fit? I recently had the same problem on an older bike, and in resolving the problem I learned that it is not uncommon for the bosses to mushroom out a bit under the pressure of the fixing bolt compressing in on them. The LBS had a small cutting tool/mill that we fit over the boss and twisted it down the length of the stud -- it mills it back to size. Worked like a charm and the canti arm slid on with no problem.

    Great info thanks!
    Yes I think it is in need of some milling, if not a new boss entirely.
    With that in mind, I will leave this to the professionals ~ scheduled an appointment at the LBS.
    Better than "finding a bigger hammer" anyway.
    cheers

  7. #7
    Member
    Join Date
    Mar 2008
    Posts
    42
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Perhaps some part of the brake is hitting some part of the frame? I have had this problem with newer suspension forks (mfrs assume users will be using disc brakes and put the v-brake mounts on as an afterthought).

Posting Permissions

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