Front Coaster Brake Mad Scientist Crazy (wear a helmet)

Discussion in 'General Questions' started by gone_fishin, Sep 30, 2007.

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  1. gone_fishin

    gone_fishin Guest

    how much cable-travel is used on a front drum brake?

    if the answer to that is "a lot" there a special lever or cable arrangement?

    i need "a lot" for a project i have going.

  2. azbill

    azbill Active Member

    I will try to measure it for you, but it works with my dual pull lever
    (v-brake on rear)
    looks like approx 1/4"...give or take 1/16"
    hope thay helps ya :D
    Last edited: Sep 30, 2007
  3. gone_fishin

    gone_fishin Guest

    it does, but it ain't the answer i wanted to hear :lol:

    thanks :)
  4. Alaskavan

    Alaskavan Guest

    That brings to mind another question. How much pressure is usually applied to a coaster brake to engage it firmly?
    Last edited by a moderator: Sep 30, 2007
  5. gone_fishin

    gone_fishin Guest

    quite a bit when you're trying to stop the whole bike at speed...but i've learned that you can get about the same effect as an average side-pull-brake when using a hand-lever on a coaster hub. a hand-lever isn't strong enough to lock a coaster, tho.

    yes, we are this-close to a working front coaster brake, the tests show a hand-lever will apply enough pressure for good speed-control and "standing." it's pretty nice so far, but we've learned there's a mechanical necessity to utilizing a full 3-4" (1/3) travel (rotation) of the arm (sprocket) in order to hold an adjustment. we need more cable-travel, and have an idea for a muliplying-lever at mid-point. this will also reduce the amount of pull i can apply, a good thing, but might make it a tad touchy as a trade-off.

    btw-this whizzer front end is made with amazing quality...just sayin' :)

    Attached Files:

  6. Alaskavan

    Alaskavan Guest

    A wild thought, but is there a way you can alter the internal mechanism to reduce the required rotation? Probably a dumb question.
  7. gone_fishin

    gone_fishin Guest

    not least i didn't feel dumb when i was searching that same question, but i haven't found anything yet that says we could do that.

    look at it this far does the crank move the rear-sprocket from full-release to a full-engagement? that's what we need for predictability (and safety)

    right now, when i release the brake and it moves in the "pedal" direction, the internals rotate along with it & that changes the adjustment by that amount of travel. after a fresh adjustment, 1st pull is perfect, 2nd pull is sloppy, 3rd pull does nothing. lather, rinse, repeat...frustrating :(
  8. Alaskavan

    Alaskavan Guest

    Okay. Been probly about 40 years since I had one apart to look at. That's a scary thought. Anyway, I don't have any other thoughts. Wish I did.
  9. gone_fishin

    gone_fishin Guest

    you know, taken out of context...that could look pretty bad for you ;)

    i been racking my brain all week only to keep coming back to the same conclusions.
  10. DougC

    DougC Guest

    I haven't ever done it, but I understand that there is a way, by putting extra washers in it somewhere.

    What some kids do with coaster-brake rear wheels when they want a freewheel (a freewheel is where there's no coaster-brake action, and you can back-peal freely) is they convert it into what's called a "free-coaster". They remove the brake cone shoes, and then they place washers in it somehow to tighten-up the amount of rotational slack between coasting and pedaling (which would be the amount of rotational slack between braking and pedaling, if the brake was still in there).

    So there does seem to be a way.
  11. gone_fishin

    gone_fishin Guest

  12. DougC

    DougC Guest

    Edit - nevermind, I'm thinking the pic was the left-side of the wheel. :p

    Okay, I don't know what happened--I meant to delete the second post I made, not the first one.

    Oh well.
    Last edited by a moderator: Oct 1, 2007
  13. Scottm

    Scottm Guest

    You guys are amazingly brilliant. I'm having a blast watching you build stuff. My mind races to fast to stop and think like you all.
  14. iRide Customs

    iRide Customs Member

    Fantastic design Augie! I know there must be a way to make it work smoothly.

  15. azbill

    azbill Active Member

    I did the free-coaster thing with my deviate back wheel
    it worked fine
    good luck !!!
    I have never seen a coaster on the front before
    another first for MBc !!!:lol:
  16. gone_fishin

    gone_fishin Guest

    i'm hoping it will be a budget upgrade that anyone could do...

    anyone notice i'm beefing up S-2.1 to be the strongest bicycle i can build, regardless of drivetrain?
  17. ocscully

    ocscully Member

    Long Pull Brake Levers

    Long Pull Brake Levers do Exist we call them V-Brake Levers. Sheldon Brown has some really good data/info on this subject at The key to all of this is mechanical advantage and to steal a quote from Sheldons web site "Long pull levers pull the cable twice as far, but only half as hard."

  18. gone_fishin

    gone_fishin Guest

    another huge breakthru! thanks!!!

    we purposely want to reduce mechanical advantage of power, coaster-lock being a real concern.
  19. Jim H

    Jim H Guest

    Augi, would it be possible to frame mount a foot pedal to actuate the brake?
  20. gone_fishin

    gone_fishin Guest

    possible, yes...but no way I go to a foot-front-brake...i'm crazy but not crazy :lol:

    just making light, Jim H...i appreciate the input :)