Someone explain please the difference b/w a gear reduction box and a shift kit!

Discussion in 'Motorized Bicycle General Discussion' started by highlander9, Nov 14, 2010.

  1. highlander9

    highlander9 New Member

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    Why is it necessary to put on a gearbox onto a shift kit, whereas without a shift kit you don't necessarily need to put one on?

    Ok, fire away!

    Thanks in advance!
     
  2. Mac

    Mac New Member

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    Down and dirty answer. Shift kit utilizes the bicycles gears , so it has a free wheeling "pedal" or chain ring so the motor can drive the chain ring without chopping your feet off, a gear box is needed for a single speed setup to get the motor operating in it's specified RPM range WITHOUT using the bicycles gear shifter. Hope that helped.

    Mac
     
  3. wheelbender6

    wheelbender6 Active Member

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    2 stroke China motors have built in gear reduction. Speed of the chain sprocket is far less than the engine crankshaft.
    Most other motors used on bikes do not have built in gear reduction (Honda, Hueshang, etc). The crankshaft speed must be reduced by a gear box (like 4G) before it can usefully drive the rear wheel.
    So if you have a Honda motor mounted in the frame of your bicycle, you must use a gear box and you can also use a shift kit as well.
     
  4. highlander9

    highlander9 New Member

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    [​IMG]

    Has anyone seen this jackshaft/motormount kit around??
     
  5. ocscully

    ocscully New Member

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    I think that the system shown above is the prototype of the shifter system from Firebelly Cycles

    ocscully
     
  6. highlander9

    highlander9 New Member

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    So If I don't use a shift kit, but I DO use a gearbox the disadvantage is I would lose out on gearing???

    I'll be solemnly waiting for someone to come up with a universal motor/jackshaft mount for 4 stroke 35cc (ie. Robin Subaru/HondaGXH/Titan)
     
    #6 highlander9, Nov 14, 2010
    Last edited: Nov 14, 2010
  7. highlander9

    highlander9 New Member

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    Yeah, I found it...

    "SickBelly"? HardBox 4stroke Shift Kit - Motorized Bicycle: Engine Kit Forum

    I don't get why this is not en route anymore for firebelly, because a.) there's less hardware for jackshaft mount+motor mount so you can use it on smaller frame bikes b.) "unimounting" seems a little redundant because the motor is mounted onto the frame, the gearbox onto the motor and the jackshaft is held in place by the gearbox...

    so what gives??
     

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