Jackshaft transmission options? jackshaft

Discussion in 'Transmission / Drivetrain' started by holdenrodder, Jun 6, 2012.

  1. holdenrodder

    holdenrodder New Member

    hi, i need to build a bike to make the 25km trip to work every day, as i am losing my licence and theres no public transport in my rural area.... :sweatdrop:
    im still trying to decide on a setup, and i still know very little, but im willing to learn. there is one reasonable hill on the way to work, so i was thinking a four stroke? any way, the main thing i wanted to ask was what transmission options are there other than a jackshaft setup? i was thinking of mounting another sprocket to a three speed hub, on the outer of the hub, and using that as a gearbox between the engine and the wheel? but im betting you guys have some better ideas, or can see the holes in my plan that i am oblivious to :grin5:

  2. Fabian

    Fabian Well-Known Member

    If you have a reasonable hill to climb and need to do so in all weather conditions and want dependable reliability, the best option is a SickBikeParts shift kit, which has been designed to work with 2-stroke and 4-stroke engines, depending on which kit you purchase.

    Best to grab the delux version as it contains all the necessary tools.
  3. loquin

    loquin Active Member

    Check out this approach. It uses a 33cc engine, and a pocket-bike CVT. At low speeds, the CVT is engaged, adding an approximate 2:1 reduction, in addition to the 3:1 gearbox. As the load decreases, the CVT ratio gradually shifts up to a 1:1

    If you had a 6:1 sprocket reduction from the CVT to the rear axle, the bike would have a top end about 33 mph, and on hills, would have max torque at about 14 MPH.
  4. holdenrodder

    holdenrodder New Member

    thanks guys, any other options i should consider? im thinking of just gearing it right up with a reasonably torquey engine, and getting upto speed with the pedals. more reliability, cheaper, and i could use the exercise anyway
  5. ColdCruiser

    ColdCruiser Member

    The cheap and easy way is a 2-stroke strap-on kit with the rear-wheel left-side sprocket ~$250, ...add bike and you're good to go! Not the way I'm going with mine, but you said cheap right? I keep hearing about guys going 50 mph+ with 66cc.


    I chose a new steel frame fatbike cruiser with a Preddy 79cc, SBP jackshaft, 3-speed hub shifter, discs, and other quality items to make it more reliable and to last longer, ...I'm into it for almost a grand already and it's not finished.
  6. SunkyWorks

    SunkyWorks Member

    The easiest 3 speed Jackshaft would work with a CW rotation being driven from the right.
    A 49cc Honda (or clone) 4 stroke with the 5:1 gearbox would reverse the rotation to give you CW.
    Last edited: Nov 4, 2015