[python] Re: FWD/RWS tadpole

Super! This is what I need! I am already looking forward to winter ;-D

(a dymaxion search brings up some interteresting pages)

It is interesting to hear there is no speed problem!

It is an interesting observation that they use a complete vertical setup, so they can change tire sizing without effect on the trail. And yes, with a spring you can create more or less the same effect as with the self centering effect (quadratic in potential energy).

Do you think it would be possible to have the derailleur hub directly connected to the two front wheels (i.e. have a axle going between the two wheels going through the hub. Possibly have two free wheels on each side of the hub as a differential?

Dirk

25hz wrote:

Bingo . . .
Here:
http://www.ihpva.org/pipermail/trikes/2006-January/041612.html
and here:
http://www.ihpva.org/pipermail/trikes/2006-January/041629.html
http://www.greenspeed.com.au/tyabb.jpg



  

That trike link is pretty cool.  It looks like the Christiania trikes, but
the rear steer would really make them maneuverable.  The FWD/RWS tadpole
that was built by Ian Sims (Greenspeed), according to him, was fast, easy
    

to
  

control and they actually raced it successfully.  I still can't find a
picture of it but the steering was based on the Dymaxion.  Paul said that
the trick to rear wheel steer is to have the pivot aboslutely vertical
    

with
  

ZERO trail.  While zero trail produces no steering "feel" or "weight" they
fixed that by adding springs to the steering linkage so the rear wheel had
some artifical "weight" to the steering inputs and it would also
    

self-center
  

then.  If I remember correctly, they didn't use a steering damper because
with zero trail, there was no tendency for the rear steering wheel to
    

shimmy
  

to one direction or the other.  It was also only one wheel drive to the
    

left
  

front wheel.


    

Oh never heard of sidewinder! Thanks! I am _considering_ building a
tadpole ... and FWD/RWS seems to be ideal -- if the speed problem can be
solved. I knew actually of a rear steered tadpole before, but upright.
Here it is:

    http://www.sortejernhest.dk/christiania-cykel/index.jsp

You see it quite often in copenhagen. They use a steering damper, may be
exactly to take away oscilations from riding at speed.

Dirk
      

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