The Ultimate Concept - Balanced CVT Rackmount

Discussion in 'Rack Mounted Engines' started by Mike St, Aug 25, 2011.

  1. Mike St

    Mike St Member

    I finished the ultimate concept in a motorized bicycle, a balanced cvt and four stroke engine, which provides smooth accleration and power at all speeds. When riding, the bike has a very light, balanced feeling; you don't even know it has a motor. Performance with a real transmission makes the bike into a moped, and far outpasses the performance of slip clutches. Note both the bicycle sprocket and the cvt drive sprocket are on the same side, the right side. Please refer to Treewk's comments on this site for info on the double-right sided drive, which is his idea. Once you feel the power and smoothness of a CVT, you never go back. This is a cool 24 inch steel frame bike using 11T/63T sprockets, top speed 25 mph. Got my carb adjusted a little better. This thing really has acceleration pop. Mike S

    Attached Files:

    Last edited: Aug 25, 2011


    TREEWK Member


    Congrats, your mab looks super. The open view of your drive chain is nice for checking chain alignment. May need to plastic wire tie a little plastic cover over top sprocket if you oil your chain, chain saw bar oil works good for me.

    Glad was able to help you with the pm`s. Thanks for the kind words.

  3. happycheapskate

    happycheapskate Active Member

    Looks good. I am not quite sure how the sprocket is mounted, but it looks like you used a multispeed freewheel hub, with a single speed freewheel and some kind of lockring or spacers to trap the cog.
  4. wheelbender6

    wheelbender6 Well-Known Member

    You must post more details. Many will want to mimic your concept.
  5. strotter

    strotter Member

    I want to know where you got that transmission!!!
  6. Mike St

    Mike St Member

    tranny from pocketbikeparts or fancyscooters

    TREEWK Member

    Happycs and members

    Back around 3-3-2009 when I came up with the double right hand free wheel concept, posted the info in "CVT`s and Comet drive lines" thread.

    Starting at post #54 thru approx post #80. It references post`s in the brother forum also.

    Hope this helps. Nuttsy came up with the CVT build before me with a left side drive. Did not know about his until after mine was done. He is a valued friend now.

  8. happycheapskate

    happycheapskate Active Member

  9. Mike St

    Mike St Member

    One More Pic

    This pic shows how compact the power system is:

    Attached Files:

  10. sparky

    sparky Active Member

    Meh... I bought "the ultimate concept" when I first came to this site 3 years ago.

    View attachment 32277
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    Folding 20" bike w/ 5:1 reverse gearbox rack-mounted to a dual freewheel hub, both freewheels being on the right-hand side, connected to 12 gauge spokes or thicker.

    My engine freewheel looks just like the others in this thread. In order to get it off, I had to grind it off. I'm thinking of putting a shim plate on the inner side of the engine freewheel this time, so that it should be far easier to remove if needed.

    Also, if you ever need to replace your engine freewheel for whatever reason, that larger sprocket (44t) will slide right on a regular 16t freewheel, and those 4 bolt holes will line up perfectly with the spokes of the regular freewheel. 16 / 4 = 4 perfect holes for those bolts to go thru.

    Very, very awesome design, indeed.

    I could have gotten the Grubee dual freewheel hub, but the engine freewheel is on the left-hand side!!! That doesn't allow me to use the SUPER compact 5:1 reverse gearbox, however... which is a huge bummer. Also, flipping the engine around would put the intake in the rear of the bike.

    I feel like this configuration adds an extra mph or two w/ the intake being in the front and the exhaust being in the back... like the Honda K-series motors.

    Love it, love it, love it.

    Too bad somebody doesn't have a bunch of these wheels pre-made for 20", 24", 26", etc. bikes.

    Design a wheel around this hub, with 10 gauge spokes, with a double-wall rim, etc... and then nearly all the pains of motorized bicycles will go away.

    Seriously... if someone could make a solid steel wheel with this hub... in pre-made configurations... they would each be worth a few hundred $$$ in my opinion.

    Just add tube, tires, bike, & engine/gearbox combo (that gearbox can be had for $20 or so).... and all of a sudden I see motorized bicycles as a reality for the masses.

    Don't understand the benefit of CVT if we both reach the same top speed. I can carry this thing up 3 flights of stairs if need be.

    THE HANDLE on my folding bike made this bike the ultimate configuration, as well, but it fell off after carrying it up so much. The aluminum was too thin at one part and cracked. But that flat plate w/ handle was something else. Still a handle on the frame for me to carry it up, but the one on the engine plate was soooo convenient.

    What an awesome bike I have.

    EDIT: Take note of the engine chain tensioner, as well. Very, very simple and solid.
    Last edited: Aug 31, 2011
  11. Mike St

    Mike St Member

    Your bike is nice, but this "ultimate concept" uses a CVT, a real transmission, like a snowmobile or moped with the weight of the engine and tranny balanced over the rear wheel.
  12. sparky

    sparky Active Member

    I have zero issues with balance. The 20" wheels & generally low frame help with that, too, I'm sure. But balance is not a concern whatsoever for the weakest of females.

    The extra weight and cost of the CVT seems unattractive if you don't have it geared for a faster top speed. If you want to accelerate faster, then use the pedals. :)
  13. Happy Valley

    Happy Valley Active Member

    Looks good Mike! I think above all you'll really like that engine. Curious if you did did any of the preemptive component upgrades, bearings etc. on the CVT we discussed?

    Ya know, 'ultimate' usually means end of the line but there is another the power from the CVT through the rear cassette cluster, lol :devilish: devilish gear ratios.

    Attached Files:

    Last edited: Aug 31, 2011
  14. sparky

    sparky Active Member


    I'd like to see a video of a couple of these CVTs zipping around.

  15. Mike St

    Mike St Member

    To Sparky: For a folding bike with 20 inch wheels, your setup is probably fine, if you don't mind a pedal start, but for bigger bikes and higher top speed, a cvt is the ultimate, especially with a 54T rear sprocket and a 26 inch wheel. It's all in how you gear it. The CVT I used is really light, and probably would add no more than 2-3 lbs to your present gearbox, and the bike would be better balanced. I have not made any changes to the CVT. It seems to perform fine as stock. I noticed that several who made changes, were not satisfied, and went back to the stock setup. I really like the acceleration from a stand-still with a cvt. It's neat. I would not have interest in running the power through a rear cassette - too complicated. I like the automatic motorscooter setup. Totally automatic.
    Last edited: Aug 31, 2011
  16. Mike St

    Mike St Member

  17. sparky

    sparky Active Member

    Forgot to ask...

    Where'd you get those shims, that go on the inside of the inner sprocket??

    Or maybe that was TREEWK's album I'd seen? Same difference... :)
  18. Mike St

    Mike St Member

    Follow Trewks posts for shims, which come from McMaster Carr.
  19. Fast4

    Fast4 New Member

    Can someone tell me where this rack comes from?
  20. Mike St

    Mike St Member

    I design my own racks. It can't be bought. It's an engineering challenge, to make
    it strong enough and light enough for this application.