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

A

andyinchville1

Guest
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 work....it 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
Plus.

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?

Andrew
 


N

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.
 
M

minibiker

Guest
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
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
 
M

MtnGoat

Guest
... 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
Plus. ...
...any thoughts? (esp on the jackshafts..the last essential ingredient)

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.
 

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  • JackshaftKit.jpg
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M

MtnGoat

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

srdavo

Well-Known Member
Joined
Nov 4, 2006
Messages
3,157
Nice detailed pics. How are the sprockets connected to the jackshaft hub? Are they welded too?

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

Zomby Builder

Guest
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

IMG_0926.jpg
 
5

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.

Myron
 
5

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.

Myron
 
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