bent dropouts + internal gear hub

Discussion in 'Frame Mounted Engines' started by pbeggs, Oct 2, 2010.

  1. pbeggs

    pbeggs Member

    I installed a sick bike parts freewheeling crankset on my 80 cc, 1960's murray beachcrusier with homebuilt jackshaft,... geared it down some,.. :devilish:
    11 tooth engine spr.
    30 tooth jackshaft input spr.
    10 tooth jackshaft output spr
    48 tooth crank input
    30 tooth crank output
    25 tooth rear hub spr.

    this gives me about 90 rpm @ the crankset @ 5000 rpm on the motor

    the result is a bike that will climb (accelerate up actually:evilgrin:) a steep hill

    tops out about 30-35 in 8th (8 speed wide ratio sturmey archer hub)

    looking at the bike after a ride i realized the hub axel had turned in the dropouts and bent them out 1/2 inch,..:confused:,.. :poop: too much torque,..:(

    anyway,... i went out to the pile of bikes by the shed and cut off the horizontal dropouts off a bmx (part of the anger management therapy from the bent dropouts was cutting the bmx up like a barbarian with a grinder:shout:) and im bolting and then welding the horizontal dropouts on the remains of the normal dropouts,.. the horizontal dropouts are about 2-1/2 times as thick steel as the originals so i hope that solves the problem:idea:

  2. 5-7HEAVEN

    5-7HEAVEN Guest

    Did you ever calculate what ratios you had in each gear? That way you can gear higher for less torque...and more speed.:idea:
  3. pbeggs

    pbeggs Member

    needed the hillclimb,.. besides up here in maine trying to go faster than about 30 on a bike is not really sane (not that my wife thinks im sane for motorizing a bike)
  4. ibdennyak

    ibdennyak Guest

    Should do it. I made my own drop outs using a 3 speed SA and also on a Nu Vinci. They are made from 1/4 inch steel....nary a problem is a couple thousand miles combined using a Titan and a 35cc RS engines. :cool:
  5. pbeggs

    pbeggs Member

    i think i fixed it

    Attached Files:

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  6. pbeggs

    pbeggs Member

    completely fixed! 100% solid amazed me as to what the bike will do now:eek:,.. it has a gear for everything from crawling up a hill (i havent found one it wont climb yet) to flat out 30 mph (i dont want or need any more speed than that):helmet:
    to me this is what a motorized bike should be,.. it is really just a bike you dont have to pedal.,.. ive put several hours on it in the last couple of days and am happy with what i have made,..:evilgrin:
    im not into high speed in fact yesterday i spent about 1/2 hour in first and second gear putting along the dirt road i live on,..( half the neighbors think im a little eccentric,.. theyre wrong,.. im a LOT eccentric:annoyed:)