Gearing problem

--OK here's the thing; I've a notion to build a 2-passenger pedal powered vehicle, but I want to set it up so that driver and passenger face each other. No problem with the layout or seat locations but I'd like it to be possible for both riders to contribute to the pedaling. Now, aside from having the passenger pedal backwards, how would one go about gearing the thing so both riders would pedal "forward"? The best I can figure out is to have an intermediate assembly with two keyed shafts, each with a spur gear, so that rotation is reversed somewhere in the drive train. Trouble is this is mechanically complex, heavy and robs power. A twisted drive belt is another option, but I've found that belts need extreme tension to avoid slipping and on a slender tubular framework this would probably want to twist, which would again rob power. Anyone got a viable plan "C"??

Reply to
steamer
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Try your twisted belt, only with a timing belt. The cogged construction should reduce the tension requirement.

Pete Keillor

Reply to
Peter T. Keillor III

There only needs to be one gear set to reverse the direction. The second pedaler's chain just goes to the gear driving the normal pedaler's pedal axle gear and you have the reversed drice needed.

-- Why isn't there an Ozone Hole at the NORTH Pole?

Reply to
Bob May

Use the back side of the passengers chain to drive the sprocket. You'll need one or more idlers for this to work but other than that nothing different from standard bicycle chain.

Real hard to explain in words but dirt simple if I could draw it.

I'll attempt a ascii drawing of it.

O passenger pedal sprocket I I I I I I I IO_ driven sprocket IO___O idler sprockets.

Wayne Cook Shamrock, TX

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Reply to
Wayne Cook

Bicycle chains have a lot of side flex in them. Obviously this is true or deraileurs wouldn't work.

You may need to put a couple of small ider pulleys in there, but simply cross the chain between the driver's and passenger's chainrings. You would only have to separate them by a half inch where they cross.

Jim

Reply to
jim rozen

One pedal sprocket "inside" the chain, and the other pedal sprocket "outside" the chain. Ken.

Reply to
Ken Sterling

That's what I was thinking. In fact, with an adjustable bottom bracket off of a child's stoker kit, one could make the tensioning idler and the second crank one and the same. You'd need to make sure one has plenty of wrap around both crank chain rings so that the chain doesn't jump a tooth or three.

Peter

Reply to
Peter Grey

"There only needs to be one gear set to reverse the direction. The second pedaler's chain just goes to the gear driving the normal pedaler's pedal axle gear and you have the reversed drice needed."

The problem with that is that the gears would have to be appx 15" in dia.

Reply to
Wwj2110

||"There only needs to be one gear set to reverse the direction. The second ||pedaler's chain just goes to the gear driving the normal pedaler's pedal ||axle gear and you have the reversed drice needed." || || ||The problem with that is that the gears would have to be appx 15" in dia.

Both cranksets drive a chain to a gearbox with two small gears.

3rd chain from the 'normal' side gear goes to the axle. You would need some provision for freewheeling at the passenger side so that crankset would not have to turn if the driver was still pedaling. Texas Parts Guy
Reply to
Rex B

jim rozen wrote: : Bicycle chains have a lot of side flex in them. Obviously this is true or : deraileurs wouldn't work. --Ya know, the more I think of this the more it seems possible. Gotta make me a "figure 8" chain and try it...

Reply to
steamer

Ken wrote: : One pedal sprocket "inside" the chain, and the other pedal sprocket : "outside" the chain. --Trouble with this is that the "outside" chain doesn't wrap around the sprocket very well; I worry about chain slipping and "cogging" on the sprocket.

Reply to
steamer

That's what idlers are for. You place the idlers where there's at least 2/3rds of a wrap around the sprocket.

Wayne Cook Shamrock, TX

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Reply to
Wayne Cook

Chain drive from the backwards running seat to the gears will drop the diameter of the gears but I'd rather not go too small or the efficiency of the gears will go down.

-- Why isn't there an Ozone Hole at the NORTH Pole?

Reply to
Bob May

Another thing for Ed to consider is that he will almost have to provide "crankshaft" pedals like a paddle-wheel boat, rather than just taking the pedals off two bikes. For a regular "bicycle built for two" (or more), the peddlers sit in tandem. I took his design to have three or four wheels and the driver and passenger to be side-by-side. Am I wrong?

If I am correct above, then I don't quite see the problem with an "inside and outside" looping of the chain. Assuming the rear wheels are to drive, then to go forward the chain must come off the top of the rear wheel driven sprocket. If it then comes to the passengers sprocket, and passes from below to above it contacting at least 180 degrees, then to an idler that has the top of its form at least slightly above the top of the passengers sprocket and it also has at least 180 degrees arc of contact, the chain would now run forward some distance to the drivers pedals and over the top of the drivers sprocket and exit below, returning to the bottom of the driven rear wheel sprocket to be joined at the start point to make a full loop. Of course, it can't do this if the driver and passenger are in-line. And it would certainly need some way of allowing free-wheeling.

Take care.

Brian Laws>Ken wrote:

Reply to
Brian Lawson

Brian Lawson wrote: : Another thing for Ed to consider is that he will almost have to : provide "crankshaft" pedals like a paddle-wheel boat, rather than just : taking the pedals off two bikes. For a regular "bicycle built for : two" (or more), the peddlers sit in tandem. I took his design to have : three or four wheels and the driver and passenger to be side-by-side. : Am I wrong? --Correctamundo; it's got 4 wheels. Driver sits in the back, passenger in the front, looking aft. Driver's position will be a foot or two higher than passenger so's I can see where I'm going..

: Of course, it can't do this if the driver and passenger are in-line. : And it would certainly need some way of allowing free-wheeling. --Yup, they are one ahead of the other, just facing each other..

Reply to
steamer

lots of replies covering everything I would have added.... A question...

How is the person facing backwards going to feel with no control? - I see people on the trains all the time feeling nervous about travelling backwards, and I suspect it'd be harder in a pushbike (is it going to be a bicycle, or a trike(or quad?)?).. if it's a bicycle, I suspect the person facing backwards will have some large initial concerns about tipping over, and the lack of "apparent copntrol"

my 2 cents,

Reply to
Des Bromilow

The crossed chain could run through tubes like the Wright brothers used or just the slack side. Charlie

Reply to
Charles Lessig

I hate to say this, but I suspect the stoker is going to barf within five miles of riding this thing. Have you run any tests with a vomitometer?

Jim

Reply to
jim rozen

Charles Lessig wrote: : The crossed chain could run through tubes like : the Wright brothers used or just the slack side. --Hey that's right! Forgot about those; nice hack, too.

Reply to
steamer

jim rozen wrote: : I hate to say this, but I suspect the stoker is going to barf within : five miles of riding this thing. Have you run any tests with a : vomitometer? --LOL! Well, it'll be like riding backwards on the train; i.e. "scenic", heh. Actually I'm going for style, not speed. It's going to be a self-propelled "art car" for next year's Burning Man. I've discovered this neat stuff called "EL-wire" (coolneon.com) and I'm looking to build a contraption suitable for the environment and capable of supporting a lightweight structure that's covered with the stuff...

Reply to
steamer

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