[python] Bipolar update

  • From: Vi Vuong <vi_vuong@xxxxxxxxx>
  • To: Python <python@xxxxxxxxxxxxx>
  • Date: Sat, 9 Jul 2011 21:30:37 -0700 (PDT)

When disassembled, it managed to fit inside a medium luggage (largest that I 
have), where the micro python would need another inch or so.  Thus it got to go 
traveling first.  Fortunately, the total weight is under 50lbs, so no extra 
luggage charge ($100?).

Climbing is rather poor, as front weight distribution is ~40%.  Walking is 
tough, and barely with a stick at the front.  Carrying the 25lb folded bike 
uphill is no fun either, so a upright folding bike is better here, especially 
in the city...

Downhill is not too scary anymore with some braking.  I can go faster than 
going uphill now :)  On the flat, I am comfortable enough to share trail / 
pathway with pedestrians now (when legal).

The 2-piece seat is marginal so I had to pick up a mesh back support on the 
trip, not bad for 
$1, http://www.google.com/search?q=back+support+mesh&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&hl=en&tab=wi&biw=1440&bih=814.
  A hotel towel would also helps.  Because the seat rest is coupled to the rear 
wheel, starting is a little tougher even with sticks, and care is required to 
ensure that the back seat / rear wheel is straight.

Luckily, while experimenting with uncontrolled rear wheel, I found that the 
bike is actually more compliant.  The rear wheel is now mostly free from the 
seat back, other than some pressure / friction, and straightens out nicely 
under weight, and seems to move slightly with the front wheel due to the 
pendulum effect, and probably vice versa (another invisible link like the bango 
steering http://www.youtube.com/watch?v=jzUr3GI_ulE).  

There also seems to be some sort of self-stabilizing effect (PSI reduction?) 
between the two wheels that deserves more analysis, beyond quick all-wheel 
steering.  Since the camera is mounted to the rear frame, so it's not very 
obvious that the rear wheel rotates unless you pay attention to the view 
through the wheel. http://www.youtube.com/watch?v=vswF-qqcwg0 ;  See the PSI 
test at 1:06-1:15.  The bike feels quite stable as going straight.  I will 
repeat the test on regular pythons...


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