SWEET - 5:1 Gearbox With Double Right-Sided Drive

Discussion in 'Rack Mounted Engines' started by Mike St, Mar 8, 2012.

  1. Mike St

    Mike St Member

    This is my new build, finished which I consider an advancement of the art of motorized bicycles because it has so many benefits over current designs, like the Dax chain drive and the GEBE belted drive. Here's some pics:
    Here are the benefits:
    1. Low cost gearbox
    2. Motor close to tire for better balance and look
    3. Use of very available 8mm sprockets and chain
    4. Double freewheel so riding as a bicycle there is zero drag
    5. Easily change out drive sprocket from 11T to 14T
    6. Best of all, chain drive for a solid reliable performance in any weather

    The red can is my silencer invention, which I will soon test.
    I am considering putting this complete unit out as a kit, if there is enough interest.
    Bicycle is the Schwinn Riverside, and the motor is the Tanaka 32cc PF-3300, which I bought for $89.00

    Attached Files:

    Last edited: Mar 8, 2012
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  2. Mike St

    Mike St Member

    Had to make an improvement: Reposition the motor mount, align the chain better. The chain was coming off, not aligned well enough, but all good now. May make a vid. The Tanaka motor just purrs along. Great motor, very quiet with my silencer, and practically no smoke. I used sta-mix semi-syntheic 2 stroke smokeless oil. It works.
  3. Silvaire

    Silvaire Member

    Some clever "out of the box" thinking with your build, Mike.

    I especially like your quick access polyethylene chain guard design!
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  4. loquin

    loquin Active Member

    Yes... First place in the "Most Innovative Use of Tupperware" category, LOL
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  5. lowracer

    lowracer Member

    Mike St,
    Install looks great & really like the freewheeling aspect...
    Last edited: May 11, 2012
  6. wheelbender6

    wheelbender6 Well-Known Member

    I'm a die hard frame mount guy, but I dig your rack mount. The way you positioned the engine lower, like a friction drive, makes a big difference.
  7. loquin

    loquin Active Member

    How many teeth on the driven sprocket ?

    Plus, it looks like #35 chain?
  8. Mike S

    Mike S Member

    I used a 54t on the driven but it is an 8mm chain.
  9. Stoney

    Stoney Member

    I am about to mount this as an axle mount on the rear Lt side (5.1 gear box). When I talked to duane (thats dax he said to get 72t sprocket and 14t for best overall and 11t for pulling trailers cargo or 20t for speed) is this correct? It seems to me mike with his set up this wouldn't be accurate!!! Who would be correct? they are both using the same motor sprockets but different wheel sprockets and claiming the same results... I honestly don't know how to calculate the correct figures and duane insists from experience that he is correct. Fyi- I didn't see this until after talking to Duane and was about to buy my parts. Now I am confused. I am looking for the best gear ratios for torque and speed 20-25mph or 23-28mph for my particular engine the tanaka 3300 - The same one mike has.
    Thanks in advance
  10. Mike St

    Mike St Member

    OK, here's how I made the speed/gear calculation. I have a 54 tooth 8mm sprocket connected to an 11 tooth sprocket on the gearbox. Using the speed calculator here, http://www.diygokarts.com/speed-calculator.html I simply put this in the calculator and it comes out to 110 mph, then divide this by 5 (the gearbox ratio) and the result is 22 mph. Here's some numbers based on the calculator:

    wheel sprocket, gear sprocket, speed
    72 14 21
    54 14 28
    54 11 22

    I used a 54T because I had one, and it is readily available. Don't know if a 72T 8mm sprocket is available.
    So 72/14 is very close to 54/11. This should help.
  11. lowracer

    lowracer Member

    Mike St,
    I'd like to see more about your cleverly engineered dual right sided freewheels?
    Do share...
  12. Mike St

    Mike St Member

    What, I already completely shared this info. The deisgn idea is NEAT TIMES, Ron. I followed his concept
    bought the parts and put it together and it all work the first time. I only designed the rack for holding the
    gearbox mount and motor motor mount, using steel and some aluminum. The driver/sprocket side
    has to be reinforced with steel and the gearbox mount are just steel strips together with some
    "L"s I made. Anyone could do this. Mike
  13. BigBlue

    BigBlue Active Member


    Should be able to use the Sick Bike Parts front freewheel sprocket adapter and a regular right threaded freewheel sprocket on a freewheel hub. Sick does carry two different kinds of front freewheel sprocket adapters. You can also buy a flanged freewheel adapter. On the regular freewheel sprocket, just make sure you don't get a bmx version.

    This might work too:

    Just saw this spider adapter to use your old chainring that you could use as a sprocket:

    Good Luck,

    AKA: BigBlue
    Last edited: Dec 19, 2012
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  14. lowracer

    lowracer Member

    I got the ACS crossfire freewheel & the 104 adaptor plate from same eBay seller.
    I got it just sitting in a drawer with new chainrings all mounted up waiting for yet another project.
    I'm interested in having a dual freewheel cassette kinda like what Scooterguy posted on his youtube vids http://www.youtube.com/watch?v=cyysF0L8CMA
  15. south_MS

    south_MS New Member

    It's a sweet looking set up. What kind of gearbox is it? Is it a custom made one ? Or did you adapt already made one to use with the bike?
  16. Mike St

    Mike St Member

    This is a common scooter gearbox, widely available that fits the 35cc engine. Search for it on the net. I think I bought mine from monsterscoorterparts for about $25. Thatsdax has them here: http://thatsdax.com/ENGINE_KIT_PARTS_PAGE_4.html. Good luck.