On 28.11.2007 16:50, Kevin Bailey wrote:
I had assumed that PSI was dependent on the ratio between the
pedal "width" (distance from the center of the pedal to the
centerline of the bike) and the BB to pivot distance. Basically,
that PSI was caused by the sideways component of the pedaller's
stroke (which attempts to turn the wheel) and corrected by the
foward component of his stroke (which attempts to straighten the
wheel.) This ratio is equivalent to that between the pedal width
and the BB to pivot distance. Put plainly, the further back you
move the pivot (without changing the pedal width), the less the
PSI. I assumed this was why the Python was better in this
respect than the Traylor/Cruzbike designs.
Hello Kevin,
I thought this too - until I built the PX.5, an
experimental prototype where the pivot was moved
25 cm further back than the normal position:
http://python-lowracer.de/pics/Python%20PX.5.jpg
PSI was clearly noticeable and the bike was hardly rideable.
Cheers,
Jürgen.
Siwmae Jurgen,
That picture seems to me like a very striking
image of a man actually sitting on a unicycle,
with the one-wheel trailer towed behind, rather
than the rider sitting on the trailer to drive
and steer the front-end/unicycle from behind, so
to speak. Wonder if that has anything to do with
PSI. It's certainly surprising that it comes back
in that layout, and makes the bike hard to
manage. Mysterious!
Cof, RhG
