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  1. #1
    Baliw
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    For hydroheads: question on lever travel with hydraulics

    The brake FAQ gave me no joy on my query: how is lever travel set in hydraulic brakes? Not the lever reach, but the lever travel. My Louise FR brakes have a set lever travel before the pads make contact with the rotor, and I was wondering if pumping more fluid in the line will shorten the travel. Then I got to wondering how the lever and master cylinder works. Why can't I shorten the lever travel by forcing more fluid in the line? A related question is, how does the lever travel adjust work on the Avid Juicy Seven?

  2. #2
    (aka SS_MB-7)
    Reputation: mike@one-speed.com's Avatar
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    You can shorten the lever travel by removing the wheel and gently pulling the lever until the pistons/pads extend slightly. Re-insert wheel and check for sufficient pad/rotor clearance. If the pads are too close, simply remove the wheel and gently pry the pads/pistons back into the caliper and re-try. This process will reset the pistons to a new starting point.

    By adding more fluid into the system, you may cause problems for when the system needs to compensate for fluid expansion. If you have too much fluid in the system, it will have no where to expand to.

    Ride Hard,
    Mike B.
    http://one-speed.com

  3. #3
    Baliw
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    Self-adjusting?

    Thanks Mike, I'll try your suggestion but one other question. With hydros self-adjusting, when I pull the lever without the rotor, then put the rotor back in place and use the brake, won't the caliper pistons re-adjust to the original position?

  4. #4
    (aka SS_MB-7)
    Reputation: mike@one-speed.com's Avatar
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    Nope. I've used this technique on Hope Minis, Formula B4 and B4 SLs, and Shimano XTR/XT. Unless you push the pistons back into the caliper, the pistons will stay in their new position. This is the definition of an open-system which automatically compensates for pad wear.
    Ride Hard,
    Mike B.
    http://www.one-speed.com

  5. #5
    Baliw
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    OK, tried it

    and it did make a little bit of difference in shortening the lever travel before full brake lock, but not as big a difference as I can make with my Avid mechs. I found out that the caliper gap can get misaligned though, if I push unevenly on both pistons (one piston can retract more than the other).

    Thanks for the advice!

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