How to change your gearing without changing your gears!

[Happy Valley]

Hey Sparky
Watched the linked video and then watched the next one too.

Heh, you don't have a folding bike do ya?
http://www.youtube.com/watch?v=MxqWlSxuKvs&feature=related

 

[sparky]

Didn't watch the video - my eyes are pretty bad, and most videos are useless to me.

It's not that long, but it definitely shows how quiet friction drives are... or at least how loud my chain drive is.

... except it looks like the "shift on the fly" system is basically a lever engager for the drive roller.

Yea, I figured that's what it had to be. I could tell by looking at all the marketing speak that something wasn't right, but I do get sucked into pretty adverts like that sometimes.

What I've sketched up is basically a two-speed variable roller system. Could readily be three speed, but as I said, that gets a bit more complex.

Yea, I still don't understand how it changes rollers, but if it'd be cheap... I want the first one you ship out! K? ;^)

 

[sparky]

Heh, you don't have a folding bike do ya?
http://www.youtube.com/watch?v=MxqWlSxuKvs&feature=related

I missed that one. I just found it funny that SimpleSimon came up with this shifter system for rollers, and I remembered the Dimension Edge system said something about shifting... was a bit odd to me.

Anyway, doesn't sound like Dimension Edge could be any better than Staton after all. But it seems like that guy just didn't install it properly... just doesn't understand physics or something.

Luckily, my folding bike came with the motor attached and shipped to my front door for just $500 with excellent support. The bike's not the greatest quality, but it's definitely worth the money.

 

[SimpleSimon]

It's not that long, but it definitely shows how quiet friction drives are... or at least how loud my chain drive is.

Yea, I figured that's what it had to be. I could tell by looking at all the marketing speak that something wasn't right, but I do get sucked into pretty adverts like that sometimes.

Yea, I still don't understand how it changes rollers, but if it'd be cheap... I want the first one you ship out! K? ;^)

Unfortunately, sparky, I don't have a shop or tools to fabricate the idea. I tossed it out there for anyone who might be interested.

If you look at the sketch I posted, the blue transparent cylinder between the two green plates represents a compression spring, with the vertical line through the center representing a cable. Pulling the cable raises the end of the lower plate in relationship to the upper (which is the fixed frame plate with the engine mounted to it), causing it to pivot around the central small shaft. That raises the smaller front roller off the tire tread, and presses the larger rear roller to the tire. Just simple geometry.

 

[Large Filipino]

SS that's Genius!

I say keep it all spinning all in line just like in your sketch then have the entire thing including engine slide on roller bearings or something similar to rollers you find in file cabinets or good tool boxes. Then connect it all to a shifter up front with a solid bar connecting it all. Middle is neutral.(both rollers aren't touching the wheel) Forward is first gear or climbing gear. Back is second gear or cruising gear. All done on the fly! And when on cruising gear the engine is further back,more room to stretch.
That idea most definitely has merit. BRAVO!@!

 

[sparky]

It's too beautiful, man!! ... now that I understand how it pivots. It's simply amazing!

 

[SimpleSimon]

SS that's Genius!

I say keep it all spinning all in line just like in your sketch then have the entire thing including engine slide on roller bearings or something similar to rollers you find in file cabinets or good tool boxes. Then connect it all to a shifter up front with a solid bar connecting it all. Middle is neutral.(both rollers aren't touching the wheel) Forward is first gear or climbing gear. Back is second gear or cruising gear. All done on the fly! And when on cruising gear the engine is further back,more room to stretch.
That idea most definitely has merit. BRAVO!@!

I like that, Large, I like that a lot. Unfortunately, I see some fab issues in making a rack/shift linkage work smoothly - the geometry varies a great deal from bike to bike - you'd just about have to fab up a custom linkage for each installation. Now, take your same idea, and instead of rod linkages go with a long throw cable mounted on a positive throw/snap lock lever arm shifter (like the old Stingray three speeds had), and you got something. I can even see a powered reverse from a friction drive along with two (or three) speeds.