Dare I say a plausable multiple roller drive for friction mount...

bigkat650

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Oct 8, 2008
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We all know how a typical friction drive works... What if by using a simple air piston- activated by pulling a small convenient lever, the typical friction drive could be transformed into a dual- roller drive, high and low gear system... Perhaps this is a solution to the idea...

Below I have several pictures illustrating how this system could work.

Use a C02 container (like one's found on a paintball gun). Attached to the C02 container is a regulator which decreases the PSI down to aprox. 100psi. Next, the constant 100psi pressure is fed into a 3-way valve, splitting the pressure into an 'A' or 'B' line. These lines each are attached to a simple 1-way exhaust valve (to prevent back pressure). Finnally, these lines feed into a small air piston called a Pancake piston, which is attached to the frame of the bike and the frame of the friction drive unit.

When the valve is opened to line 'A', the piston opens up to either 1, 2, or 4 inches (whichever fits the application best), and the back roller contacts the tire. When valve 'A' is closed, and valve 'B' opens, the piston retracts, contacting the front roller with the tire.


There are only two potential problems I see with this set-up:

The chain that would be used to turn both rollers would have to spin at a high RPM. I feel the best chain to do this would be a timing chain, since they are designed for hard usage.

The addition of a chain and second drive roller would add a small amount of resistance to the motor.


Ultimately, I don't know if this system would work. I was thinking it was plausible though. I have never built any kind of motorized bike, but am very intregued by the thought. And since I am a larger guy, I thought this system might provide both a high torque and higher speed options. Please leave some comments guys, and sorry about the vagueness of the pictures, I hope they are self-explanatory.
 

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bigkat650

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PS, the price of the valves, regulator, tubing, piston, ect. I have calculated around $150 American dollars.
 
J

JemmaUK

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This was done back in the 50s/60s with a spring mechanism... but I dont know how effective it was..

there was someone looking for something like this who eventually went with a twin engine set up...

Jemma xx
 

Happy Valley

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Why not?

Not sure about the technical needs for the pneumatics....something simply mechanical (and cheaper) might suffice.

Keep at it though, just a matter of time before someone comes up with changeable, on the fly gearing for FD. I'll be first in line.:D
 

bigkat650

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i looked for a 3-way valve system that would run off a small electrical toggle switch (perhaps small battery powered) rather then a manual lever. However I couldn't find one, that's not to be said one doesn't exist. If someone has the means/time to try this out, i'll let ya know where i found all the component. The air piston with 100psi should hold down with over 100lbs of pressure-which should keep good pressure on the tire. The tricky part would be figuring out how long of a stroke needed to push the motor mount down to the precise point, and making sure that when it was retracted- it put the correct pressure on the tire with the other friction roller. I think it would take a little bit of tinkering, but I think it is very plausible it would work rather well. With that being said, I don't think a 'kit' could be fabricated only because it has to be rather precise... But once its in the correct place, it should be something that will last for the long haul.

I don't know how long a typical c02 cartridge would last, but I would think it would be at least 100+ switches, could be several hundred or more before it requires recharge... aaand that cost what, 5 bucks at a typical sporting goods store. Basically, it would require almost zero cost once the initial price for the components was spent.

I don't know... it was just a thought I had and figured I would share with you great people
 

Mountainman

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that's what I was thinking also

Why not?

Not sure about the technical needs for the pneumatics....something simply mechanical (and cheaper) might suffice.

Keep at it though, just a matter of time before someone comes up with changeable, on the fly gearing for FD. I'll be first in line.:D
yes -- I think that you are on to something here

but remember there should be a way to keep it very simple

and also please note
just in case you truly come up with something new
if you post these thoughts in those (as above) fine pictures of project
some one will be sure to steal you idea
it's not the mountain way -- but just the way that some are these days

ride that thing
 

bigkat650

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true... i would just hope if it was a successful idea- and even if someone did steal it, they would at least send me working version of it lol. or cut me in on a little of those profits :p
 

Mountainman

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I shouldn't laugh

even if someone did steal it, they would at least send me working version of it
guess what -- THIS IS A TRUE STORY

the Sting-Ray bicycle was (very first one built)
right here in Hillcrest Calif -- part of San Diego
built by a father and son team ---- late 50s or early 60s
many pictures in that bicycle shop telling the whole story
Hillcrest Bicycle Shop
Scwhinn stole the idea
and guess what they gave the inventor

one new Sting-Ray bicycle ------- THAT'S ALL

watch out what we pray for -- we just might get it !!!!!!

ride that thing
 
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bigkat650

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lol well i'm not looking to invent something... i really was just looking to put the idea out there. If someone does invent it, that's fine. I'm not a material guy... i'm more of a sharing of information guy. If people are happy from something i've thought of, thats awesome and really reward enough... but a free working version of my model wouldn't hurt!!
 

Mountainman

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that's very cool bigkat

i'm more of a sharing of information guy. If people are happy from something i've thought of, thats awesome and really reward enough... but a free working version of my model wouldn't hurt!!
well - that's the least that they could do for you

not to get lost here and forget
I LIKE YOUR IDEA
can you simplify it any ?

maybe instead of hoses and valves ect
cables and springs ?

I don't know -- it's your thing -- got to love the idea !!!!
maybe low gear 10mph up ANY HILL
high gear 35 to 40 mph no strain on the level ???

ride that thing
 
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