Jackshaft jackshaft/gear ratio ?

Discussion in 'Transmission / Drivetrain' started by Spitfyre, Jun 30, 2009.

  1. Spitfyre

    Spitfyre New Member

    i have a twenty six inch mt bike and a 80 cc black stallion. i want to make a jackshaft so the gears work. but dont know what size sprocket to use on each side. i weigh two hundredy twenty five pounds and live in a very hilly area. any recommendations? bike will either be 18 or twenty one speed. will i be able to use all the gears?
    Last edited: Jun 30, 2009

  2. duivendyk

    duivendyk Guest

    You are not all that informative I must say.Do you want to build a jackshaft and drive a sprocket of your front deraileur and use another one to drive the rear cluster?.Why not have done with it get the SBP kit instead.Does that engine have a clutch & built in reduction?,you will need a freewheel crank in any case.
  3. Hawaii_Ed

    Hawaii_Ed Member

    I agree, fabbing up a jackshaft kit is not easy, and sick bike parts has already sorted it out for us. Their kit bolts on, allows the full use of your rear gears, and is well worth the $$$.
  4. pdxrhett

    pdxrhett Member

    i can't figure out why you need a freewheel on the jackshaft - the rear wheels already have a freewheel?
    Just slap a freewheel on the bottom bracket so pedals don't spin, and you're good.
  5. Hawaii_Ed

    Hawaii_Ed Member

    Right, you don't need one on the jackshaft and the BB, like you said, slap one on the bottom bracket so the pedals can freewheel under power.
  6. cspaur13

    cspaur13 Member

    Go do a search for jpilots gear ratio calculator on here.

  7. 17t on left and 10t on right

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