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V brakes front v back difference?

Discussion in 'Bicycle Mechanics and Repairs' started by summerdays, 19 Apr 2008.

  1. summerdays

    summerdays Cycling in the sun Staff Member

    Location:
    Bristol
    Just been looking at V brake callipers and noticed that there are back and front wheel versions ... what is the difference between them ? ... and in an emergency could you use the wrong one?
     
  2. not a lot it is just the noodle (A curved piece of metal tubing used to lead the brake cable around a right-angle bend) the back is a 45 degre angle and the front is 90 degre.
     
  3. OP
    OP
    summerdays

    summerdays Cycling in the sun Staff Member

    Location:
    Bristol
    Thanks - so keeping the old bits as spares would be useful - just remember to use the right noodle!:becool:
     
  4. 02GF74

    02GF74 Über Member

    i can't imagien ti wold be the end of the work if they noodles were fitted back to front.

    presumably the 90 degree on at the fornt is to allow for longer cable and cable length changing due to front syspension compressing.
     
  5. Steve Austin

    Steve Austin The Marmalade Kid

    Location:
    Mlehworld
    its also the brake blocks themselves. Some are longer at one end than the other, and others are blocks in a holder that won't work very well (the force of braking 'could' force the pad out of the holder) if fitted at the wrong end.
     
  6. e-rider

    e-rider crappy member

    Location:
    South West
    So, the differences are: the noodle - 135 degree bend for the front and 90 degree bend for the rear; the bolts that attach the brakes to the frame (or fork) are nearly always longer on the front brake; and sometimes as mentioned before, the brake blocks can be different but these days most brands use blocks that can be used for front or rear brakes.

    So, the noodle bend and the fixing bolt length are the usual differences.
     
  7. Rong! Front is 135 degrees, rear is 90. Pillock :smile:
     
  8. what ever...


    I have to much to do to be right all the time
     
  9. P.H

    P.H Über Member

    I've never come across this and the Shimano exploded diagram for my brakes only has one size. I can't think why there'd be two.
     
  10. Tim Bennet.

    Tim Bennet. Entirely Average Member

    Location:
    S of Kendal
    Yes, the noodles have been the only difference in all the V-brakes I have fitted. And that difference is unique to the UK as we have our front brakes on the right. The rest of the world manages with the same noodle back and front. Worth remembering if you pick up a bargain on your hols! Not that it should prevent you snapping up a bargain as individual replacement noodles are available here.
     
  11. 02GF74

    02GF74 Über Member

    I don't believe this either - I've never noticed any difference in bolt length. Wny should that be - the boss on fram forks is the same length so why would a manufacturer complicate things by having different bolts? As far as I can tell the levers themselves are identical.

    As for pads, I've not seen any that are different between front and rear - eiether when I was using blocks and now with the holders - yes, the holders are direcitonal with p[ad being held by a pin but you then swap over the sides -no difference between front and rear pair.

    I should point out my expereience is limited to shimano xtx/xt/dx/lx and avid v-brakes.
     
  12. They are different but only inasmuch as the pads are directional and are therefore installed the other way round in the factory. It wouldn't make economic sense to manufacture specific fronts and rears. Bolts may be different front and rear, I install aluminum bolts on the rear (because they are unloaded) and Ti bolts on the front (because they are loaded).
     
  13. OP
    OP
    summerdays

    summerdays Cycling in the sun Staff Member

    Location:
    Bristol
    Do you mean by that, that more of the force of braking goes through the front wheel/brakes? and that therefore you could use a stronger bolt and that Ti bolts are stronger?

    (Told you I wasn't good at mechanics or physics - but this thread has had more information than I was expecting in it - thanks for all the replies:smile:)
     
  14. Er... yes and no....

    Certainly the front brake handles more of the braking forces but the reason I use aluminum and titanium bolts is to save weight over the stock bolts.

    Because the front brake usually resides on the front of the forks any braking force transferred from the front rim pulls directly on the bolts. Braking forces transferred to the rear brake simply force the brake onto the frame via the brake bosses. The rear bolts have nothing to do but hold the brake on, they're not under any significant load so I can get away with short, lightweight but relatively weak aluminum bolts. All of the front brake loads are transferred through the front bolts so I use Ti which is stronger than alooniman but still lighter than steel.