Jackshaft jackshaft kit through the bottom crank

Discussion in 'Transmission / Drivetrain' started by dirbob, Sep 16, 2009.

  1. dirbob

    dirbob New Member

    just a thought. why not put the jackshaft through the bottom crank? it could be done in such a way that you could have your jackshaft turning the original gearing of the bicycle and still maintain the freewheel on the pedals. you could have all your original gears and still have power from your engine. the only problem i have is what is rpm reduction in the engine to output shaft in 2 stroke engine?

  2. Just_Gasit

    Just_Gasit Member

    How would you "freewheel" both crank arms? I'm asuming your running a chain to the left side of the bottom bracket to spin what is now the pedal crank shaft. It would work but I think you would have to remove the pedal crank arms completely and use foot pegs at another location.
  3. 5-7HEAVEN

    5-7HEAVEN Guest

  4. dirbob

    dirbob New Member

    jg i already have it figured out how i would do it. both cranks will freewheel and the engine will drive through the gears. i have a spare bottom crank laying around and figured it might be an interesting winter project. will let you know if it comes out. i just threw it out in case anybody had there own ideas. bob
  5. dirbob

    dirbob New Member

    5-7 already knew about sbp. that is where i got my original parts when i first started. i just took there original concept a step further. they have a dynamite jackshaft kit, but if you are going to 4 stroke it, your on your own. sbp uses the rear gears, i already have made a hub that i use both the front and rear deraileur. this gives me access to 21 gears instead of 7. i never use that many but seeing it is a mountain bike. it gives me access to higher or lower ranges. so you can have gears for the hills or the flat. i am just going to take it a step further and see if i can clean up my design a little. it is just an interesting hobby, and seeing how i have nothing to sell, just thought it would be interesting if others would think about it also. lord knows we need companies like sbp,staton,dax and all the other reputable companies out there. bob
  6. POPS

    POPS Member

    Hi Dirbob

    So how did you do this...please do tell...POPS
  7. Elmo

    Elmo Member

    me too

    I am also interested in your method of accomplishing this.
  8. spad4me

    spad4me Member

    Staton was selling a kit called BIMOTO that used a double freewheel front crank.
    They were kind of pricy.
    The front freewheel setup was about $300.00.
    I don't see them anymore on his site.
  9. Fabian

    Fabian Well-Known Member

    Hi dirbob

    Can you please post some hi-res pics of your jackshaft setup - having the option of very low range and very hi range gears appeals to me.

  10. dirbob

    dirbob New Member

    elmo: i am working on it now. parts i am using are on back order. when i get it together will post pics. basically i am going to run bicycle crank through a hollow shaft through bearings in bottom crank. gears on both sides are connected to hollow shaft with freewheel connecting pedal crank to hollow shaft with bearing on opposite side of crank to support crank. that way engine can drive gear train without pedals turning or if you do pedal you can turn gears also. pretty basic just a matter of putting it together to see if it will work. anyway that way you will still have all your gears that you have on bicycle. i already made a hub but it drives on the right side, so it is not necessary to go through the crank, so i know that part of it works. you can shift front deraileur but i wouldn't do it without backing off on the throttle. rear is good to go at any time. hope this helps. bob
  11. dirbob

    dirbob New Member

    fabian: here is a pic of what i have so far. it dosen't go through the crank yet. but i am working on that. This one drives off the right side from rear mounted engine. with it i can cruise at 25-30 mph and still make 9-11 mph on the steepest hill i have found. I havent had to pedal at all which at my age is important. hope this helps. bob

    Attached Files:

  12. dirbob

    dirbob New Member

    spad 4 me: haven't seen staton bimoto kit but i know he has some good quality products. i am running his 460 clutch in my honda gxh50 along with his 4500 springs along with various gears and adapters. i haven't got anything from them that wasn't good quality and wouldn't hesitate to recommend them to anyone. the only problem with his site is it takes me a long time to find what i want to buy. bob