Eccentric Transmission

I ran across this in the recumbent bicycle newsgroup, it reminded me of the
giraffe chainring discussion here. Has anybody tried something of the sort
on a Uni? Seems like it would address the loss of power when the cranks are


Harper, now that we know you are able to make working hubs and stuff, are you looking for a summer project? This could be a good one to work on when classes arent going on.
-David Kaplan

I may look really unaware here, but this doesn’t seem to me like it is much different from the elliptical chainrings that flopped. In principle, the chainrings worked as they were designed, but it turned out that for those who knew how to pedal efficiently (spin) the chainrings were more of an annoyance.
Those plots for torque assume the cyclist applies force only in a direction normal to the ground. That is why torque is represented as 0 at TDC and BDC. In fact, if that were the case, it would not be possible to free mount a unicycle the way most of us do because you would be unable to apply any torque to the pedals once on. In fact t graph of their linkage is pretty representitve of the torque applied by an experienced rider on a conventional setup. The device seems to reward bad pedaling technique. Not for sure though.

I test rode a bike with that system at the Seattle Bike Expo. The bike was stationary on a trainer, but it did let me get the feel for how it pedals. It was very difficult to pedal it in an even circle with even pressure on the pedals. It’s like Biopace chainrings all over again, only more so. There were some people at the bike expo who liked them, but I’m still scratching my head trying to figure out how they considered it an improvement.

It’s only use on a unicycle would be for a novelty giraffe that you take to UNICON and challenge people to try to ride it. I’m sure it could be ridden well with practice, but put someone on it for the first time and it would be a difficult and amusing ride.


Nah…find a mechanical engineer to do it.

I don’t teach either. The only thing that changes for me during the summer is that there’s more room on the bus on the days that I take it.

without mentioning any of the above said,that system is crap!more beringz,more weight,more hassle,need i say more?Shimano has been there by the way, with some old Durace pedal crank combo.i cant remember the model name but it floped worse than Biopace.

Then what the hell do you all day at the University? Are you just a janitor who happens to be extremely advanced in physics, and electrical engineering?
-David Kaplan

Re: Eccentric Transmission

Harper could start a collection of projects proposed/suggested to him
by UniDak. I think this was #3?

Klaas Bil

On Wed, 24 Apr 2002 22:30:40 -0500, UniDak
<> wrote:

>Harper, now that we know you are able to make working hubs and stuff,
>are you looking for a summer project? This could be a good one to work
>on when classes arent going on.
>-David Kaplan
>UniDak - David Kaplan
>I think that English was never meant to be taken seriously. Its kind of
>like A cartoon language… transient and flexible like the elastic,
>animated characters of old. -Greg Harper
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