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  1. #1
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    Calipers short/long reach --- how to measure

    I have an old Raleigh frame, and it has 27" wheels on it. To slow down --- or sometimes actually stop I am using some cantilever brake calipers. Now, the way that those guys allow me to align the pad is only in the rotational manner - relative to the caliper arm - obvious. There is no way I can adjust it so it actually sits right on the rim during braking (only a small part of the pad touches the rim diagonally --- some interesting noise it makes aswell).

    I looked up some Tekktro sidepull brakes --- there are two different models: short and long reach expressed in mm'ers. now, is this the distance from the bolt to the position of the pad, right?

    correct me if I am wrong ... or perhaps tell me how could I make those Cantilever's work- increasing the mechanical advantage by moving the pads more out ?

    regards

    kermit_xc

  2. #2
    eminence grease
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    Quote Originally Posted by kermit_xc

    I looked up some Tekktro sidepull brakes --- there are two different models: short and long reach expressed in mm'ers. now, is this the distance from the bolt to the position of the pad, right?
    kermit_xc
    Reach refers to how far down you can position the pads relative to the rim. Long reach are used on frames that accept a bigger tire as standard reach caliper on a bigger tire would not allow the brake pad to completely clear the tire. Longer reach lets you push the pad down a bit more in order to clear the sidewall. I'm using long reach calipers on my fixie as it uses an eccentric hub that positions the tire further away from the brake bridge. With standard reach calipers, the brake pad catches a tiny bit of tire when braking.
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    B2
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  4. #4
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    Quote Originally Posted by B2
    That is what I was looking for. Thanks

  5. #5
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    Quote Originally Posted by kermit_xc
    I have an old Raleigh frame, and it has 27" wheels on it. To slow down --- or sometimes actually stop I am using some cantilever brake calipers. Now, the way that those guys allow me to align the pad is only in the rotational manner - relative to the caliper arm - obvious. There is no way I can adjust it so it actually sits right on the rim during braking (only a small part of the pad touches the rim diagonally --- some interesting noise it makes aswell).

    I looked up some Tekktro sidepull brakes --- there are two different models: short and long reach expressed in mm'ers. now, is this the distance from the bolt to the position of the pad, right?

    correct me if I am wrong ... or perhaps tell me how could I make those Cantilever's work- increasing the mechanical advantage by moving the pads more out ?
    Before you look at brake reach, there are a few other questions that have to be answered first. If your bike presently has cantilever brakes, can it even accept sidepull brakes? Is there a brake bridge on the rear stays, and is it drilled for a sidepull brake mounting bolt? Is your fork crown drilled for a sidepull brake?

    As far as adjusting your present cantiver brakes - does it use studded pads, or threaded pads (i.e. do the pads have a smooth post that is clamped into the brake arm, or is the post threaded, and held into a hole or slot in the brake arm with a nut on the threaded post)? If it is a studded pad, and there is no adjustment on the stud holder, then you might be out of luck. But if the brakes use threaded pads, then you can buy replacement pads (or pad holders) that use cupped washers, that will allow the pads to be rotated on 3 axes for adjustment.

    Finally, you can't change the mechanical advantage of any brake by adjusting the pads. The machanical advantage is determined by the distance between the brake arm pivot and the rim, regardless of the shape of the arm or how the pads are adjusted.

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