[python] Re: Bipolar - a double-pivot folding python
- From: Vi Vuong <vi_vuong@xxxxxxxxx>
- To: python@xxxxxxxxxxxxx
- Date: Mon, 11 Apr 2011 23:15:03 -0700 (PDT)
Hi Dirk,
Yes, the rear pivot is somewhat redundant in terms of steering, and auxiliary
at
most (only during turns). However, it's primary purpose is to enable 2 folds
for compactness, yet without any folding locking mechanism and seat removal
like
the commercial Grasshopper or Cobra or the μPython. I was prepared to make a
pivot lock in case it's not ridable, but after some testing, it seems that I
can
skip the lock and consider the extra instability as a compromise / feature.
Over the next few months, I will be comparing its mobility / utilization vs.
the μPython, going different places. The μPython will probably win the
popularity contest, with the tiny motorcycle tires alone.
There is a steering linkage between the wheels, an organic one (the rider). I
was surprised that the weight of my back is able to keep rear pivot / wheel
pretty steady going straight without any correction effort, not much different
than regular python. Some coroplast friction between the backrest and seat
bottom helps, at least walking the bike. Turning is more different, almost a
new experience, very smooth like butter and without moving the shoulder
outward.
Perhaps, this is its best riding characteristic, which I would recommend
people
to try.
Maybe, I will lock the front pivot just to see with how RWS only feels like,
but
not for speed as discussed here before. I don't think I can go very fast on my
exercise routes, flat dirt/gravel trail, ~10mph (16km/h). The μPython clocks
in
at 7mph, fast than some joggers :) Check out this race between a big wheel and
a bus
http://gas2.org/2011/04/11/video-man-beats-bus-on-big-wheel/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+IM-gas2+(Gas+2.0)
Cheers,
Vi
________________________________
From: "dirk@xxxxxxxxxx" <dirk@xxxxxxxxxx>
To: python@xxxxxxxxxxxxx
Sent: Sun, April 10, 2011 11:31:28 PM
Subject: [python] Re: Bipolar - a double-pivot folding python
Hi Vi,
it is another, somewhat redundant degree of freedom...there was a project a few
years ago on this list. I brought up this issue once and juergen cleared me up
on that ;-)
i have my reservations whether one can safely control a double pivot setup.
Maybe, if you link the two together, so you end up with connected steering?
- DirkS
Vi Vuong <vi_vuong@xxxxxxxxx> hat am 11. April 2011 um 06:36 geschrieben:
> Here goes a bicycle version of the Skatecycle, same folding requirement as the
> μPython, to fit in the back of small car boot with seat up. For 20" wheels,
> double-pivot folding mechanism is used for max compactness. The seat is split
> into 2 pieces, with the backrest mounted to the rear pivot to control the rear
> wheel, which makes this bike all wheel steering (AWS), with rear wheel turning
> only when the body leans into a turn. Turning feels tighter and smoother than
> regular python; going straight is not too bad, but instability seems more
>sudden
> / unpredictable...
>
> Also see more use of sticks for stabilization
> (skiing?) http://www.youtube.com/watch?v=USd9OYN4BEY
>
>
> ________________________________
> From: Vi Vuong <vi_vuong@xxxxxxxxx>
> To: Python <python@xxxxxxxxxxxxx>
> Sent: Sat, April 2, 2011 10:39:48 AM
> Subject: [python] 2-Headed Python (Skatecycle)
>
>
> In case RWS is not challenging enough...
>
> Interestingly, first prototype has one 1 pivot like a python, then evolved to
2
> pivots; see http://www.youtube.com/watch?v=kzoQ1JrTVgk&feature=related
>
> Vi
http://dirk.steuwer.de
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