Bang gears for less....Multispeed for engine!

Discussion in 'Performance Mods' started by andyinchville1, Nov 8, 2007.

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  1. HI All,

    Well, actually...."bang less" shifting but I will get to that in a bit...

    I recently posted in the thread "3 speed motorized bike experiment" my idea on how to achieve multi speeds for our engines (center mounts mainly but could be used with racks too)...While the idea would was fairly labor intensive and the machine work for the adaptor and 1 weld would have boosted cost beyond what I think most would want to spend.....

    Then I began thinking Nuvinci....Seems ideal and heck Staton I think is already has tested it on some of their bikes...BUT what is the draw back there?....Well beyond the obvious (hub cost) we will still have to have a jackshaft to get the power to the "right" side of the bike)...So I figured...which is easier....Manufacturing,designing, and custom machining or simply getting a better price on the hub itself?.....I thought the latter and I can get the Nuvinci's for less (about $275 (maybe less but being conservative) delivered to anywhere in the lower 48)....That's the discount price for members of this great forum....If I tried to sell elsewhere I'd probably bump the price $10 or so....Just an idea for now BUT I digress...

    The only problem I have now is the Jackshaft....I like the one Blaze I think made in another post BUT I need to find a ready source for jackshafts that
    would fit on our bikes without a lot of fuss...Is there anything out there like that now or are we back to more custom machining....Not a problem but I like easy!...Bolt on ability ( I think that's an Augi phrase!...Thanks Aug) is a BIG

    As far as the sprockets adaptor goes I think we could buy the piece Staton makes for something like $25 (the piece that allows the engine to drive 1 sprocket while the rider pedals using the other sprocket....a freewheeling sprocket....this would allow for compression engine starts and stationary pedals when the engine is running....Hmmm.....with 350% gearing would we still need custom sprockets....Hmmm...YES! ;-)

    So there you have it....The long awaited Multispeed tranny for engine and rider....any thoughts? (esp on the jackshafts..the last essential ingredient)

    Does it still seem pricy?....I wonder what the jackshafts would run or should that aspect be left to the end user....of course that may deter alot of people...BUT then again aren't we all tinkerers?


  2. noah

    noah Guest

    just a thought

    How about mounting a drive sprocket to the pedal crank and using the 5-8 gears on the rear sprocket as your "transmission". Using a freewheel crank
    of course. Just a thought.
  3. minibiker

    minibiker Guest

    i did this but wlded too soon i have a track hub wit a fixed gear on the right and another on the left with another freewheel i got the whol set up for $70 iff ya want it lemme know and ill sell it @ 65 for an MB.c special
  4. MtnGoat

    MtnGoat Guest

    Yes, lots of thoughts. Jackshaft first.

    I've been scouring the forums here looking for details on how to build and assemble jackshafts, because I've come to the same conclusion you have. Just about any scheme for multispeeds requires a jackshaft. My mechnical background is limited to putting together a couple of simple rack mb kits, and performing a few mid level bike repairs, like replacing a crank and bottom bracket. So when it comes to building jackshafts, I'm starting at the bottom of the ladder, with no motorcycle, scooter or other motorized vehicle experience to build on.

    I've seen some references in various posts to gokart jackshaft kits, but no details on how to adapt them. Seems like these would be a good starting point for standardizing a simple jackshaft for motorized bikes. What do you think?

    Here's a pic of a standard kit. (i.e. if my first attempt at attachment works) I don't understand how to mount the rotating shaft to the bike frame. Obviously need some bracket, bolt on would be ideal, like you said. I don't get the concept of those washers with one flat side. They're called bearing hangers, but what the ... ???. Do they fit around the bearings, snap lock or something? Then what? I don't understand the intent of those, but maybe they simplify everything?

    It would be nice to have a thread devoted to general jack shaft installation. Maybe edit the title if there is some interest.

    BTW, I've seen Zombie Zack's and Blaze's excellent pics. But I'm thinking the gokart kit might make for a great less custom, more universal application.

    Attached Files:

  5. srdavo

    srdavo Active Member

  6. MtnGoat

    MtnGoat Guest

    Nice detailed pics. How are the sprockets connected to the jackshaft hub? Are they welded too?
  7. srdavo

    srdavo Active Member

    yes, the sprockets are welded to the hubs. the hub bearings can still be re-greased or replaced as needed.
  8. Jackshaft for bicycles

    The bearing hangers flat side is supposed to be welded to a gocarts rear deck. The holes in the hangars house the bearings. I welded the two hangars together so that they house two bearings. The other side is supported by a european crank adaptor that just bolts into a regular bottom bracket. It also houses two bearings so you have a driveshaft that has 4 bearings.

    Z Bob #3 frame.jpg

  9. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool: MtnGoat, your question would be good for an IQ test.

    The flat bearing hangers are welded onto a flat platform and support the bearings, which then support the 5/8" jackshaft. After you install the sprockets, you would place two locking collars onto the shaft, one each on the inside of the bearing hangers.

    You could also place the collars on the outside of the bearing hangers, or one inside and one outside the hangers. Inside placement of the collars look better, IMO.

    That would prevent any side movement, and secures the shaft and bearings onto the hangers.

    As a comparison, visualize a barbell set, suspended by the posts on a weight bench. The barbell plates on the outer edge of each side restrict side-to-side movement. Similarly, if you placed the plates on the INSIDE of the bar, they would also restrict side-to-side movement.

    The "bar" also has locking collars, one on each end. if locked in close to the posts of the weight bench, the collars themselves would be enough to restrict side-to-side movement.

  10. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:Besides fabricating the jackshaft, the first problem will be to calculate gear ratio to best utilize engine's torque/hp range. The next obstacle is finding/selecting proper sprockets to attain the ratio.

    Happy time engines have a built-in 4.1:1 gear reduction. without this option, one MIGHT have to utilize rather large jackshaft sprockets, or maybe two jackshaft assemblies. This is especially true if yours in a 12,000 rpm chainsaw engine.

  11. MtnGoat

    MtnGoat Guest

    Standarized jackshaft for NuVinci

    Thanks Myron and Zomby Builder. Now I've got it clear in my mind, how those bearing hangers/washers work. I'm thinking these might be replaced by the bracket that attaches to the bike frame, using the same sized hole to attach to the bearing.

    Zomby Builder, do you think it is necessary to double the bearings for a typical MB jackshaft? Or was that something specific to that one project?

    Myron, I'm already comfortable calculating the gear reduction values, due to reading some of your previous posts on the subject. Thanks for getting me up to speed on that score. And you didn't even know you had! Like I said I've been scouring the forum for any information I can find about jackshafts.

    Andrew was hoping to find or develop a standarized jackshaft for the purpose of easily using the NuVinci hub in mb applications. Getting in the right range might be difficult when using the NuVinci hub off a single jackshaft that moves the drive to the right. The usual Happy Time setup reduces an additional approx 4 to 1 by going from the drive sprocket to driven sprocket on the wheel. 4 to 1 makes for a pretty big sprocket on the jackshaft if one can't get any additional gear reduction going from the jackshaft to the NuVinci hub. Seems Staton is using a 36 tooth driven sprocket on the NuVinci hub, AFTER already reducing the ratio to 18.75 to 1 in his gear box. I don't understand why such a big 36 sprocket is appropriate, but I'm sure he's got it calculated correctly.

    The NuVinci at $250-300 with sprocket would be quite attractive. My only reservation is the weight, assuming I could work out the gear reduction and right side drive issues cost effectively.
  12. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:MtnGoat, you're welcome. A few builders here have welded an extra crankset bracket into the frame. There are special components to convert it into a very strong(but not adjustable) jackshaft.

    When most people consider using the NuVinci hub, they fail to take into consideration that David Staton is using this hub in conjunction with his gear chain drive gearbox.

    There is an 18.75:1 gear reduction BEFORE it links with the NuVinci hub. The hub does not openly advertise what its gearing is. HOWEVER, through some speed/rpm stats advertised on STATON'S website, one can calculate what the NuVinci hub's gear reduction range actually is.

    You'll be surprised.:shock:

    Dave starts with a 26" bicycle, using a 22t drive sprocket on his gearbox and a 36t on the NuVinci hub.

    At 7,000rpm, maximum speed is 9.49 mph in lowest NuVinci gear.

    This computes to a low drive ratio of 58.7:1 final drive:shock:, as compared to happy time engine with 143t sprocket.

    At 7,000rpm, maximum speed is 32.9 mph in highest NuVinci gear.

    This computes to a high gear drive of 16.87:1, as compared to happy time's engine with 41t sprocket.

    Therefore, the NuVinci hub has gear spacing of a LOW 1.913:1 and a HIGH of .55:1.:shock:

    Any enthusiast thinking about installing this hub should realize that they need to factor in some MAJOR gear reduction at the jackshafts...

    ORRR design the STATON gearbox into their drivetrain.

    Here's what would happen if you linked the NuVinci hub directly with your happy time engine. This is with NO gear reduction at the jackshaft(10t sprockets on both ends):

    At 7,000 rpm, maximum speed is 19.72 mph in lowest NuVinci gear.

    This computes to low drive ratio of 28.24:1,as compared to happy time engine and 69t sprocket.

    At 7,000 rpm, maximum speed is 68.6 mph in highest NuVinci gear.

    This computes to a high gear drive of 8.12:1, as compared to happy time engine and 20t sprocket.

    At first glance, one might say that the NuVinci hub MIGHT work with a direct happy time connection. HOWEVER, one would not be using the intermediate and high gear to its fullest advantage. This is especially true if you run an 8500rpm MITSUBISHI or an 11,500 rpm pocket bike or chainsaw engine.

    Hope this helps prevent a few expensive nightmares.:confused:

    Last edited by a moderator: Nov 12, 2007
  13. Hmmm...Actually it may be GOOD to run the HT without a lot of reduction prior to going into the NuVinci...reason being there is a lot of twisting that must go on at the controller for the hub to go from one extreme to the other (the hub is shifted by rotating a twist grip type control....If we only have to use a little bit of travel to cover the wide range you mentioned I think we'd be set.....I mean a 20T to 69T sounds like all the range I'd ever want.....I heard that HT engines on a single sprocket shouldn't go much below 32T anyways...BUT 20 T on a down hill with full!

    As far as cost....If we can get a good easy to attach jackshaft...we'd have the multipeed tranny issue almost licked because I can get us NuVinci's for about $275 delivered to your door in the lower 48 .....We are just soooooo close!
  14. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:Hmmm, Andy, I guess someone here will do it, sooner or later.

  15. HMMMM might be me!!

    OK you could probably get away with only using one bearing on each side. I do this because you see all the sprockets are on the right side. I tryed this red bike set up with nothing but the bottom bracket bearings. No hangars. It looked real clean & worked great for 50 miles. Then the shaft chewed up the right hand bearing. Too much cantlever on the shaft. If you had the driver on the left it may be OK. I would still use one hanger on each side as well as two additional bearings inside the bottom brackets for a left handed driver. I am wanting to do this with a Whizzer motor. As soon as the Whizzer motor can be started with the new electric start I will. So count me in on the discounted NuVinci. This setup should have awesome torque with a 22 tooth driver on the left & the smallest possible reduction sprocket on the right, and a 22 tooth on the NuVinci. You could do this now with a happy time, I just want a higher quality motor. Why spend the time and $$$$ doing this with a $100 motor???

    If you want an inexpensive jackshaft: just weld those hangers on each side of a stock bottom bracket. It would be an easy weld that any amateaur welder could do. Then just weld in the bottom bracket into your frame. Use the bearings that come in the kit & drive it on the left reduce it on the right & ROCK ON DUDE. Just put the bearings so that the short side faces your drivers.
    Last edited by a moderator: Nov 12, 2007
  16. MtnGoat

    MtnGoat Guest

    Staton - NuVinci gear reduction

    Myron, check my math and inputs, since it doesn't match yours. NuVinci hub range from their website is 0.5 - 1.75.

    Staton set up highest gear:
    18.75 * (36 nv sprocket / 22 Staton drv spkt) * (.5 nuvinci H reduction) = 15.34 to 1
    You have 16.87 to 1

    Staton set up lowest gear:
    18.75 * (36 nv sprocket / 22 Staton drv spkt) * (1.75 nuvinci H reduction) = 53.69
    Your value was 58.7 to 1

    Where are we differing? I want to make sure I'm doing this correctly.
  17. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:MtnGoat, I'm using .55:1 instead of .5:1, utilizing the stats taken off STATON'S site.

    I'm also using 1.913:1 instead of 1.75:1 for the same reason.

    That computes to +.88(to 10.37 mph) in low gear, and +3.4(to 36.3 mph) on the high end.

    The proof will be in the actual experiment, not our theoretical calculations.

    Last edited by a moderator: Nov 12, 2007
  18. MtnGoat

    MtnGoat Guest

    It's good to know I've got the method right. That's what I wanted to check. I get the same reductions you do when I put in the Staton site numbers.
  19. Method??

    Please fill me in with how these numbers relate to my boney arse. With a bike that weighs conservatively 100 lbs. With a 200 elbo rider.. You guys make this sound like an equation that is real. Are you considering HP?? Or just gear reduction?
  20. 5-7HEAVEN

    5-7HEAVEN Guest

    :cool:Zomby, gear reduction is an important factor. It helps calculate rpm at mph, and are general theoretical calculations. It becomes more specific when the rider's engine's HP and torque ranges are known.

    Total weight, wind resistance, friction losses from all aspects will detract from these mathematical calculations.

    They are simply ballpark figures. They show if you're within your engine's power range, or 'way out in left field.