Gears

[George]

I am in the design stage of a multi person "bicycle" and am looking
for information on gearing systems. Basically I need a system that
allows the different cyclist to pedal at different speeds and
therefore supply different levels of power. And for as much of this
differential power to be transfered to the drive train.

Can anyone point me in the right direction?
Does anyone know of any good resources?

[Phil Brown]

>Basically I need a system that
>allows the different cyclist to pedal at different speeds and
>therefore supply different levels of power. And for as much of this
>differential power to be transfered to the drive train.

DaVinci does this as well as the Opus Counterpoint now made by Bilenkey.
Phil Brown

[Dave Lehnen]

George wrote:
> I am in the design stage of a multi person "bicycle" and am looking
> for information on gearing systems. Basically I need a system that
> allows the different cyclist to pedal at different speeds and
> therefore supply different levels of power. And for as much of this
> differential power to be transfered to the drive train.
>
> Can anyone point me in the right direction?
> Does anyone know of any good resources?

A conventional tandem forces the same cadence for both riders, but
not the same power. Each rider can pedal as hard or easy as he/she
desires.

I've seen a tandem with ratchets in the cranksets which lets either
or both riders coast independently of the other. I think these were
Shimano cranks, not sure, and don't know if they are still made. The
pedals are not forced to stay in phase.

Differentials would allow each rider to choose the cadence, but
force the same torque from each rider, or at least a fixed ratio of
torques. Good luck finding any differentials light and strong enough
for bicycles.

I don't know the configuration of your vehicle, but it might be
possible to provide each rider with an independent complete
conventional drivetrain, driving a common axle. Each rider could
choose gears and coast as desired. You could probably machine
adapters for old-style freewheels to fit on a common axle.

Good luck.

Dave Lehnen

[Jeff Wills]

Dave Lehnen > wrote in message >...
> George wrote:
> > I am in the design stage of a multi person "bicycle" and am looking
> > for information on gearing systems. Basically I need a system that
> > allows the different cyclist to pedal at different speeds and
> > therefore supply different levels of power. And for as much of this
> > differential power to be transfered to the drive train.
> >
> > Can anyone point me in the right direction?
> > Does anyone know of any good resources?

Others have pointed out that there are tandems that allow independant
*coasting* (the DaVinci and Vision recumbent types). The
Bilenky/Counterpoint Opus tandem features somewhat-independant gearing
for each rider driving the rear wheel. There are a couple custom
recumbent builders that build tandems with elaborate drivetrains that
allow independant gearing for each rider. One of these is Lightfoot
Cycles:
http://www.lightfootcycles.com/HTML/tandembikes.htm
Some recumbent tandems have completely independant drivetrains: the
captain powers the front wheel, the stoker powers the rear wheel. ZOX
makes one like this:
http://www.zoxbikes.com/index_e.html

Interestingly, at last May's HPV races in Portland, only one of the
five multi-rider entries had a "normal" tandem drivetrain. The rest
had independant drivetrains for each rider:
http://www.ohpv.org/pir2003/theracers/pages/calvin18.htm
http://www.ohpv.org/pir2003/theracers/pages/don008.htm
http://www.ohpv.org/pir2003/theracers/pages/don080.htm
http://www.ohpv.org/pir2003/roadrace/pages/neils106.htm

Jeff