Shifting gas bike idea

Discussion in 'Motorized Bicycle General Discussion' started by fang_x, May 1, 2010.

  1. fang_x

    fang_x New Member

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    Well I was brainstorming ways of getting more speed and torque out of the gas bike (Gearing), i was thinking of ways to accomplish this, and a solution i have found is this. To basically use the existing bicycle drive train and derailleur to be able to shift the power from the motor. Below is a small diagram of how it would function.

    [​IMG]

    -Remove crank arms and pedals
    -Weld sprocket to pedal bearing
    -set chain tensionier to keep chain from rubbing on the motor's exterior
    -Test out the new derailer system
    -Hope fully the stock bike chain and rear hub will be able to withstand the torque from the motor
    -Maybe buying a heavy duty DH bike chain would help, as well as a good quality rear hub / wheel.

    what do you guys think?

    I will also have to lock the rear HUB, as the bike would need to be roll started but this would not work with the ratchet systems rear hubs use .shft. Unless i leave one crank arm on to start it, but not having it on permentally, kind of like a key lol, keep it in my bag or something

    Apon further research, this appears to be simmilar to a "JackShaft", except i dont need pedal power, who needs that lol?
     
    #1 fang_x, May 1, 2010
    Last edited: May 1, 2010
  2. ocscully

    ocscully New Member

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  3. Cabinfever1977

    Cabinfever1977 New Member

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    You can get a pullstart addon to start it, and some foot pegs for your feet.

    As for peddals some of us need them to pretend were peddaling and for when you run out of gas or engine stops working,walking the bike home isn't fun.
     
  4. charles.paskell

    charles.paskell New Member

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    How are you gonna get the chain to line up on the pedal drive sprocket? it looks good in
    2-D but your motor drive gear is on the opposite side of the pedal drive gear.... unless you have a magic chain. i dont believe this can be done with these china girls but i have been wrong before so go for it.....
     
  5. Cabinfever1977

    Cabinfever1977 New Member

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    Thats why he uses 2 colors,the blue one is on the other side and would go from engine down to a sprocket mounted on the left side of peddal axle and on the right is red which is another sprocket that leads to the rear gear changer and wheel.

    But on the left side of engine is a cover that covers the small sprocket on engine which he would have to cut a opening on the bottom of the cover for chain to go down to the left peddal axle.
     
    #5 Cabinfever1977, May 1, 2010
    Last edited: May 1, 2010
  6. simonjohnwilmer

    simonjohnwilmer New Member

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    If you dont want pedals buy a motorcycle , easier all round , I like motorized bicycles cos they are bicycles . and yeah the cops want to see me pedaling .
     
  7. fang_x

    fang_x New Member

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    i may just mount the engine up higher on the frame, so the angles will lign up, i don't like the idea of cutting it.


    And to to those giving me **** about how it wont have pedals, the first gas bike i had i installed with pedals, and the way it was intended, but the torque from the motor to the rear wheel was too great and ended up warping the spokes, so a solution i made was to get a disc brake wheel/ hub, and mount the sprocket to the spot where the rotor would go, by drilling out holes... that has worked for about a year now... the bike has failed on my a few times, but i always carry a tool pack with me, with the essential bike tools, allen keys, wrenches, ducting tape, extra fuel line. A year later now, the gas bike runs just as good as it did..

    I was doing all this with a budget, and parts i had accesble.


    im now undergoing a new project converting a chopper bike, i wont do this method, although i will have a pretty interesting build.

    Im using parts from a 1970's honda 50cc moped i got my hands on, mainly the rear wheel, i checked it out and it turns out the rear wheel's sprocket is the same size teeth as the gas bikes, so i will be able to use it. it has a built in drum break, witch works really well, so that will help to break the bike.

    I already modified the frame to accommodate the larger rear axle size, i am now undergoing painting of the chopper bikes frame, i choose a "Pumpkin orange" looks pretty good so far.

    The plan is to take parts from the moped and attach it to the chopper, Ie generator, headlight, horn.


    i'll take photos
     
  8. mapbike

    mapbike Active Member

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    If you will read what he said and look at the diagram he posted you will see that the engine will drive an added sprocket that would be attatched ( or as he said welded) to the pedal crank shaft that is on the engine drive side of the bike, this would of coarse do away with the ability to pedal the bike any longer but would make it more like a motorcycle instead of a bicycle. It would work just fine but no more pedals and thus no longer a bicycle which would probably get you thrown off the road by the law in most if not all states.

    Best idea is S.B.P. shift kit.....will do the same but with the added bonus of still being able to pedal..
     
  9. happycheapskate

    happycheapskate New Member

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    I have been thinking of running a cheap bike this way. If you use a frame that takes the old square-taper spindle (common stuff, really), and get a matching cheap crank, you can have cranks on both sides of the spindle.

    This will make a bicycle that REQUIRES the operator to pedal while the engine is engaged.

    This is not as bad as it sounds if you have a reliable clutch lever and kill switch, and/or you use a centrifugal clutch.

    If it was a bike geared like a "10 speed", you will have plenty of top speed and plenty of ratios to save your legs.

    If you have BMX pegs on your rear axle, you don't even have to pedal the bike once you get started, and still have full hand controls. If your frame is small enough, you can still sit on the seat conventionally with your feet on the BMX pegs.

    I like it. The biggest problem will be matching or tensioning the chain on the motor side.
     
  10. simonjohnwilmer

    simonjohnwilmer New Member

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    I was looking at my 2 stroke and thinking about this idea , its been mentioned that the drive sprocket cover is only open towards the rear , I cant see how it could be done without mounting the engine forward of the pedal crank . I wouldnt bother , it would end up being a not very elegant set up , but maybe theres a way . maybe .
     
  11. professor

    professor New Member

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    Of course there is a way to do it. You use two idlers to angle the chain down from the output of the motor.
     
  12. wheelbender6

    wheelbender6 Active Member

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    Your idea is interesting, but it would be easier to install a shift kit from SBC.
     

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