3-Speed motorized bike experiment

[turbo/chaos]

is ther a way to make it that the motor can run a bicycle chain so the other side can be threaded to fit the 3 sped setup with a tensinor but then that might not work im not sure

 

[minibiker]

i am just days away from getting a 6 speed motored bike i got a cheap mountain bike from my freind i have everything all mounted all i need to do is titen chains add a free wheel sprocket another chain and do some tuning on the handle bar shifter this is coming along amazingly easy i hope i didnt screw anything up and i hope it works cuz if it does i should haul a$$ at least 45 and more if it will get will get to the lowest gear maybe 65 (i hope i hope i hope i hope )

 

[Zomby Builder]

Shifter

I tryed to make a similar setup. It works BUT the narrow chain that travels across the sprocket cluster kept jumpin off then SNAP. Thrashed a lot of parts. You really need at least a BMX size chain with any motor. & those are too wide for a cluster sprocket. If you make it work, my hats off to ya. If you need some semi thrashed parts to experiment with, let me know. I have a box full.

 

[minibiker]

im starting to get mad at this thing cuz i get it all set up about ready to try it and somthin goes wrong right now i have a bad sprocket on my jack shaft that has the wrong teeth for the 6 speed so thats another trip to the bicycle shop they arnt open til sunday so im off the bike till then and if i cant get it to work im out like $70 plus i gotta buy a new bicycle chain and drive chain for it my question is WHY DONT IT WORK AS GOOD AS IT DID ON PAPER AAAAAAAAAAUUUUUUUGH!!!!!!! this is startin to drive me nuts

 

[cheap ride]

Hi minibiker, keep your chin up, i and many others would love to hear you succeed with the three speed experiment, if you succeed then i will be doing the same design.

 

[minibiker]

after taking a break for a while i am ready to do it to it. i found out i got a flat tube but thats an easy fix im getting closer by the day i will get pix up ASAP.i should be able to get to the bicycle shop today for another sprocket i hope it works

 

[andyinchville1]

OK....this is how I was going to do it if I had time (work has been crazy tho so maybe another tinkerer will do this?)....Engine output to Jackshaft to get power output to the right side of the bike...Output of jackshaft drives a sprocket (custom machined...not a problem for us to make) that is fitted to a SRAM dual drive hub (the sprocket will slide on if machined right)....A freewheel (old fashioned screw on type NOT casette) would have to be fitted to the SRAM via a machined adapter (the SRAM dual drive hub cannot be machined for threads to allow the freewheel to screw on because there is not enough "meat" on the metal for the threads....hence...that part would have to be machined / cut off and a threaded tube would have to be affixed in it's place...be careful as there are bearings in there tho...Also a spacer may have to be machined to give some distance between the slip on custom machined sprocket and the largest sprocket on the freewheel....In essence this makes for a 3 speed engine tranny (altho gear spred is pretty wide) and about 72 speeds for the bike itself (3 speed hub times 8 cogs on the screw on freewheel times 3 chainrings up front). The freewheel on a freehub allows for engine compression starting and allows the pedals to remain motionless while riding under engine power.

Somebody please gofor it!.... wow I WISH I had more free time! HA

Andrew

 

[minibiker]

i gave up on my project cuz i had bad mounting and welded too soon everything was off
but i m annoyed cuz i spent $70 on the jackshaft set up now i got nothin to do with it i will be willing to sell it for $65 it has 1 sprocket for drive 1 sprocket for wheel drife and a freewheel to pedal stard and keep pedals stationary.

 

[MtnGoat]

3 speed jackshaft

Here's my idea for a 3 speed rig. I think it's original, but maybe I just haven't found it elsewhere yet.

1. Engine output on left side (either frame or rack mount) to behind seat post jackshaft, which moves output to right side and reduces gears as desired.

2. Output from right side of #1 jackshaft connects to 2nd jackshaft lower on the seat post tube. This jackshaft is made from a 3 speed hub. Input goes to the normal hub cog input on the hub's right side, which freewheels. Output is back on the left side, where a sprocket is attached to the hub spoke flanges. Further gear reduction can be gained by a smaller sprocket on #1 jackshaft to larger input sprocket on 3 speed hub. Sturmey Archer hub is available for around $60 new that goes from .75 - 1.33. No disk brake set up though, unfortunately. That would make for easier more secure attachment of left side output sprocket.

3. Output from left side of #2 internal hub jackshaft to rear wheel. Again there is opportunity for more gear reduction. Connect to wheel by disk brake hub, staton or grubee hub, or 9 hole spoke attachement.

That's it. The rest is only details - building jackshafts, attaching jackshafts, adjusting tensions, choosing sprockets and chains, ... oh my!

 

[andyinchville1]

I feel your pain about the jackshafts....I am still doing Net searches when I can and still have not found anything ready made....I may have to give in and build one when time permits....