[python] Re: Bipolar update

  • From: Vi Vuong <vi_vuong@xxxxxxxxx>
  • To: "python@xxxxxxxxxxxxx" <python@xxxxxxxxxxxxx>
  • Date: Mon, 11 Jul 2011 22:03:25 -0700 (PDT)

Original intention was for maximum compactness, but I am liking the 
easy-to-fold more and more, as I discover that locking the pivot is not 
necessary.  Folding is also a way to make the bike on its own.  It would be 
nice to make the bike folds flatter like the IF-MODE 
bike http://www.google.com/search?um=1&hl=en&biw=1440&bih=814&tbm=isch&sa=1&q=if+mode+folding+bike&oq=if+mode+folding+bike&aq=f&aqi=&aql=undefined&gs_sm=e&gs_upl=2290l3844l0l8l7l0l0l0l1l349l568l2-1.1l2

Riding on the flat is easier among my python fleet, but uphill is probably 
worst, like a true python slithering up a slippery slope.

Just by chance, I stumbled on a solar powered LED decorative light that is of 
the reptile theme, which should be good for a "safer" night 
ride, http://www.ikea.com/us/en/catalog/products/70200939

Vi


>________________________________
>From: Olaf Johansson <noll@xxxxxxxxx>
>To: "python@xxxxxxxxxxxxx" <python@xxxxxxxxxxxxx>
>Sent: Monday, July 11, 2011 12:56 AM
>Subject: [python] Re: Bipolar update
>
>
>
>
>I'm probably just envious on your easy-to-fold frame design. 
>
>
>Does the bike slither more when you go uphill and have to push hard on pedals 
>( increasing the body's side-to-side movement?)
>
>As for the snake skin, don't forget the fangs!
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>
>
>Olaf
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>11 jul 2011 kl. 09:17 skrev Vi Vuong <vi_vuong@xxxxxxxxx>:
>
>
>if the rear pivot points forward, the rear wheel probably would counter steer 
>and makes the bike unride-able at 60 deg.  As is, I can park the bike with the 
>wheels turned in opposite direction to make it look uninviting :)
>>
>>
>>Looking at the second video from an observer point of view, the bike does 
>>meander more like the real animal.  http://www.youtube.com/watch?v=abNt5v9CsHg
>>Maybe it's time for a python skin shell (costume)... 
>>
>>
>>
>>
>>
>>>________________________________
>>>From: Olaf Johansson <noll@xxxxxxxxx>
>>>To: "python@xxxxxxxxxxxxx" <python@xxxxxxxxxxxxx>
>>>Sent: Sunday, July 10, 2011 1:11 PM
>>>Subject: [python] Re: Bipolar update
>>>
>>>
>>>
>>>
>>>Nice! What would happen if you changed the design so that the rear wheel is 
>>>countersteering? That would perhaps make turning radius even shorter? Maybe 
>>>it would make it impossible to ride straight? Making it unrideable. And 
>>>theft-proof.
>>>
>>>
>>> 
>>>Olaf
>>>
>>>
>>>
>>>
>>>
>>>10 jul 2011 kl. 21:26 skrev Vi Vuong <vi_vuong@xxxxxxxxx>:
>>>
>>>
>>>Riding hands-free is great, especially when the scenery is nice.  Best 
>>>comments I got from the trip are:
>>>>
>>>>
>>>>That't not fair - from someone riding roller blades
>>>>He's lying on a bike - from a kid
>>>>Can we make that bike? from another kid
>>>>...
>>>>
>>>>
>>>>
>>>>
>>>>http://www.youtube.com/watch?v=abNt5v9CsHg
>>>>
>>>>
>>>>
>>>>>________________________________
>>>>>From: Vi Vuong <vi_vuong@xxxxxxxxx>
>>>>>To: Python <python@xxxxxxxxxxxxx>
>>>>>Sent: Saturday, July 9, 2011 9:30 PM
>>>>>Subject: [python] Bipolar update
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>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...
>>>>>
>>>>>
>>>>>Vi
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>
>>>
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