gears, why not use an old bikes derailleur shifter mechanism

[thedarlington]

ive seen lots of 2 and 3 speed transmissions lately but dont we already have a derailleur transmission on bikes in the first place? how easy would it be to chop the lower part of the diamond off an old bike, put a motor on the end where the crankarms go, and a friction drive on the other end and put that on top of the wheel? maybe the ratios would be off but would this be atleast possible? because it would be pretty cool to have an 7-8 speed tranny if we could use the cassette derailleur parts of a bike and im sure would be easier to find and chop than machining custom parts

 

[thedarlington]

also, does anybody know what controllers would be a good match for these? the first one is pretty impressive it claims equivalent to a 100cc gas engine, although for the price the other two might be better, but i get the feeling those 2 are over volted, and the same could be done with the first one to maybe 70-90v

http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14427

http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14426

http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=5139

 

[spinningmagnets]

From Bluefang:

and "woody goes shopping" a push-trailer:

 

[Thud]

hello thedarlington,
To answer your 1st question: the issue with bicycle gearing is the spacing. the ratios are very close together to optomise the limited power of human legs. Our electric motors have a much wider power band (nearly linear) & function mutch better with a wide ratio. but it isn't unprecedented. Look at a cyclone, or a jackshaft kit the motored bike guys are using.
http://endless-sphere.com/forums/viewtopic.php?f=30&t=20840
Also, I have the CA80/120. it runs on an CCHV160.....but it really strains it looking at the logs....its a killer motor.(i have not mounted it to anything with wheels yet) Member Olaf is setting up a pit bike racer with one with it re-terminated in wye using a sensored controller. I will prolly re-wind mine & optomise it for 60v & add a sensored controller. (I have high hopes for Jeremys new design) The smaller 80/100-130 motors are popular & run fine on the big Castle controllers.

 

[Lessss]

I have an MY 1080 motor 900W that I had a bikes rear sprocket welded onto the MY1080. I built a TRASH push trailer with it but it was too DAMN fast so dismantled it. I'll rebuild it eventually as a proper push trailer with a smaller motor. Will likely put the 900W MY1080 in a bike frame or sell it. Haven't gotten round to though.

 

[hydro-one]

why not skip it all and just have a cone shaped motor bell. with another axis of freedom in the standard friction drive ala grinhill, you could achive a CVT type effect. eh?

 

[spinningmagnets]

Clever! My tires have a very round profile, so a cone-shaped Kepler-type of system would be a fun experiment. If one side of the tire started to show wear, you could just shift the drive over to the other side and reverse the motor?

ES member Storm suggested this:

 

[LI-ghtcycle]

Clever! My tires have a very round profile, so a cone-shaped Kepler-type of system would be a fun experiment. If one side of the tire started to show wear, you could just shift the drive over to the other side and reverse the motor?

ES member Storm suggested this:

Nice! That is a very simple CVT, love to see someone make that work!

 

[thedarlington]

that simple cvt frictio ndrive is an excellent idea! you could use some sort of knob to adjust your 'gear ratio' by pulling the motor cone in or out, to deal with the tires you could also tilt the whole assembly to different angles to get the tire from the top, topside, other topside, sides etc, that first picture is awesome i know gears are made to suit slow human legs, but thats why i thought about reversing the roles, so that the small cassette gears where on the motor side like the cone, and the big ring was attached to power the wheel side thru a friction drive or attached to the wheel, this is getting interesting, can you guys recommend a controller for those 80cc equivalent motors? i may have to try some of this out

 

[olaf-lampe]

that simple cvt frictio ndrive is an excellent idea! you could use some sort of knob to adjust your 'gear ratio' by pulling the motor cone in or out, to deal with the tires you could also tilt the whole assembly to different angles to get the tire from the top, topside, other topside, sides etc, that first picture is awesome i know gears are made to suit slow human legs, but thats why i thought about reversing the roles, so that the small cassette gears where on the motor side like the cone, and the big ring was attached to power the wheel side thru a friction drive or attached to the wheel, this is getting interesting, can you guys recommend a controller for those 80cc equivalent motors? i may have to try some of this out

How much torque is such a friction drive able to handle?
I'd guess a 80ccm equivalent motor is way out off league?
Only my 2 cent. I've never built a friction drive...
-Olaf

 

[electraflyit]

I think you will tear the tyre apart quite quickly with the cone type fricton drive.
As it pushes down into the tyre for grip the contact patch widens, this area sees different speeds across the cone.
I could be wrong, but just visualizing it my mind it seems it can't work.
Eddie

 

[JohnH]

I think you will tear the tyre apart quite quickly with the cone type fricton drive.
As it pushes down into the tyre for grip the contact patch widens, this area sees different speeds across the cone.

That makes sense to me. The larger-diameter part of the cone has a higher speed in SFM (Surface Feet per Minute) then the narrower part for a given RPM. What about a stepped cone, much wider I suppose? If you spring it to move away from the tire when not powered, you could drop power to shift. Next I suppose you'd want to figure out the right ratios to use an indexed twist-shifter to move the assembly left-to right just the right amount to center the tire on each diameter. I think the stepped version would need to be a lot "taller" (longer axis) to give wide-enough steps.

 

[grifftek]

I think you will tear the tyre apart quite quickly with the cone type fricton drive.
As it pushes down into the tyre for grip the contact patch widens, this area sees different speeds across the cone.

That makes sense to me. The larger-diameter part of the cone has a higher speed in SFM (Surface Feet per Minute) then the narrower part for a given RPM. What about a stepped cone, much wider I suppose? If you spring it to move away from the tire when not powered, you could drop power to shift. Next I suppose you'd want to figure out the right ratios to use an indexed twist-shifter to move the assembly left-to right just the right amount to center the tire on each diameter. I think the stepped version would need to be a lot "taller" (longer axis) to give wide-enough steps.

Here is a cone type drive that was developed for gopeds, maybe something like this could work for a bike? http://img113.exs.cx/img113/7903/dscf00148tx.jpg

http://img113.exs.cx/img113/7903/dscf00148tx.jpg