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Recumbent What IS that thing?! Recumbents may be odd looking, but they have many advantages over a "wedgie" bicycle. Discuss the in's and out's recumbent lifestyle in the recumbent forum.

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Old 09-01-07, 04:52 PM   #1
joe99
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Non-circular pedal action

Just wondering...

Are there any commercial production recumbent trikes using a non-circular pedal action? I am sure that experimental builders have tried all sorts of variations involving elliptical cranks and other such devices.

One obvious possibility would be the arrangement traditionally used on a child's pedal car where the pedals swing back and forth on arc with connecting rods going to a driven crankshaft.

It seems to me this would avoid wasting the rider's energy in raising and lowering the centre of his legs so much. It would also provide better forward visibility and the possibility of a smaller front fairing. It might also be possible to avoid using such a long chain.

I am certainly not claiming any of this to be novel ideas, but I am simply curious as to whether anybody has ever managed to apply anything along these lines to a production machine.
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Old 09-01-07, 05:19 PM   #2
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I don't know about production, but I rode a guy's 'bent in June that had a custom machined elliptical chainring set. I didn't much care for it.
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Old 09-01-07, 05:27 PM   #3
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Just wondering...

Are there any commercial production recumbent trikes using a non-circular pedal action? I am sure that experimental builders have tried all sorts of variations involving elliptical cranks and other such devices....
Two I know of....
Gary Hale makes a "glider" LWB recumbent:
http://www.halebikes.com/index.html

The Sherer trike uses a linear pedaling system:
http://www.shererusa.com/

....I like the function of the Sherer type of system in particular, because it does not limit the rider to a specific pedal stroke length.... I have a pet theory that (if it were technically possible) bicycle riders would prefer to take lots of little pedal strokes [keeping their legs nearly extended] when cruising over level ground--and they'd take fewer, deeper pedal strokes when climbing hills--just like people do when they are jogging.
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Old 09-01-07, 05:36 PM   #4
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I don't know about production, but I rode a guy's 'bent in June that had a custom machined elliptical chainring set. I didn't much care for it.
I have Rotor Q-rings on my long-distance LWB.

I have them set up not to maximize power, but to take the load off the upper end of the pedal stroke and push it down into the lower end. My knees ached with round chainrings, specifically my knees ached during the top half of each pedal stroke. I can ride considerably longer now, and at that time the Q-rings was the only part of the bike I'd altered, so for that I can definitely say they work.

The two complaints I have are that shifting onto the small ring (of a triple road set) doesn't work real well, though my front derailler is rather inexpensive.... And at the time Rotor didn't have a 42T road ring available at all--and even now, they don't want to sell a 30-42-52 chainring set. I'd have liked to match my 30-42-52 round rings, but I had to settle for 30-40-52.
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Old 09-01-07, 05:37 PM   #5
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At century rides in Huntsville Al for the past 4yrs I have seen a rowing bent that
uses push pull action alternately on the steering and pedals to turn the rear wheel
with a cable that is wrapped around a stepped cone. The derailleur shifts the cable
up and down the steps to provide different drive ratios. It has 5 speeds and looks
sort of like a 15-24 freewheel. Never have seen it under way as I think he rides
toward the back of the pack.
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Old 09-01-07, 05:56 PM   #6
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Thanks for the links Doug. The Sherer is more or less what I had in mind. Except that I am a little surprised that he evidently found it necessary to have such long pedal arms. Long pedal arms have the effect of gearing the machine down, so that he then needs multi stage chains to gear it up again. In fact he seems to have finished up with more rather than less chain. I also take the "twice as fast" claim with a grain of salt!

As far as the "depth of pedal stroke" issue is concerned, are you suggesting more than one pair of pedals on the same arms?
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Old 09-01-07, 11:27 PM   #7
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Originally Posted by joe99 View Post
Just wondering...

Are there any commercial production recumbent trikes using a non-circular pedal action? I am sure that experimental builders have tried all sorts of variations involving elliptical cranks and other such devices.

One obvious possibility would be the arrangement traditionally used on a child's pedal car where the pedals swing back and forth on arc with connecting rods going to a driven crankshaft.

It seems to me this would avoid wasting the rider's energy in raising and lowering the centre of his legs so much. It would also provide better forward visibility and the possibility of a smaller front fairing. It might also be possible to avoid using such a long chain.

I am certainly not claiming any of this to be novel ideas, but I am simply curious as to whether anybody has ever managed to apply anything along these lines to a production machine.
Vaccum Velicopede had a linear stroke:

http://www.pedersenbicycles.com/vacuum.htm
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Old 09-02-07, 06:33 AM   #8
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As far as the "depth of pedal stroke" issue is concerned, are you suggesting more than one pair of pedals on the same arms?
No, not two sets of pedals. The Sherer trike doesn't need them.

On the Halebikes glider recumbent, it uses what we could call "semi-linear" pedaling, but the stroke lengths of the pedals are fixed, because the pedals are still connected (by rods) to a regular set of crankarms. If those crankarms are 175mm's, then the pedal stroke distance is going to be 350mm all the time.

On the Sherer trike, the pedal stroke length isn't set--it just has a maximum you can't go beyond, and a minimum that's dependent upon the freewheel's ratcheting pawls. So you could use any stroke distance you wanted, inside those limits. Plus--if the upper limit was wide enough, you could use your legs nearly extended part of the time, but use a deep "lunging" stroke at other times.

And I think that the pedal arms on the Sherer seem kinda long, too.
And the Sherer system isn't *perfect*, in that there's no way to assist on the pedal upstroke, and that the only way to recoil the primary chains is by spring tension, that you must pedal against all the time. But I'd still bet that most recreational cyclists would benefit from such a system.
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Old 09-02-07, 02:51 PM   #9
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Thanks again Doug. Reading you explanation and studying the pictures again I now understand how it works. I see now that a second set of pedals would be equivalent to the rider both changing gear and changing his stroke at the same time so that they would not provide any real benefit.

One question however. Are the pedals arms connected by some sort of "see-saw" linkage so that they always move equal and opposite? If so, would not this enable the rider to pull as well as push? If the pedals were not interconnected, he could use different length of stroke on each pedal or even give one leg a rest altogether. He could also use both legs together, a bit like a swimmer doing a "dolphin kick". By pushing against his shoulders rather than his lower back, he could use his back muscles as well as thigh muscles. Possibly opening up new possibilities of pain and injury not previously available to him!
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Old 09-02-07, 03:19 PM   #10
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Thanks again Doug. Reading you explanation and studying the pictures again I now understand how it works. I see now that a second set of pedals would be equivalent to the rider both changing gear and changing his stroke at the same time so that they would not provide any real benefit.

One question however. Are the pedals arms connected by some sort of "see-saw" linkage so that they always move equal and opposite? ....
They don't appear to be connected in the photos to me, but I've never seen one IRL or heard from anyone who owns one. He wants $4500 for the things(!) and I'm not real interested in tadpole trikes overall anyway.
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Old 09-04-07, 10:30 AM   #11
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I use Q-ring elliptical chainrings on my trike. They're great! They really do smooth out the pedal stroke, enough that switching back to round rings feels unnatural and jerky. Highly recommended.

The Scherer trike is the only production trike that I know of that has "non-standard" pedals by default.
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Old 09-04-07, 12:48 PM   #12
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i guess i got lucky when i bought that bike for $15 with the shimano bio-pace cranks on it........im not sure i notice much of a difference tho...........but i put em on my bent and they work good......as far as i can tell..lol
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Old 09-04-07, 12:48 PM   #13
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actually the first time i rode it i thought they were bent........then i looked closer and realized they were oval
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Old 09-05-07, 08:30 AM   #14
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actually the first time i rode it i thought they were bent........then i looked closer and realized they were oval
The BioPace rings aren't oval, they're more of a "rounded diamond" shape, with four corners. And the shape is not as offset as the Rotor Q-rings are:
http://www.norcom2000.com/users/dcim...hainrings.html
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Old 09-05-07, 09:40 AM   #15
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wow i didnt realize there were so many different types...........thx doug
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