[python] Re: baby python
- From: Jürgen Mages <jmages@xxxxxx>
- To: <python@xxxxxxxxxxxxx>
- Date: Sat, 10 Jan 2004 17:15:12 +0100
Olaf,
very cute, that baby! I can see no reason why it should not work.
Steering angle around 80 degrees like its parents. Rear suspension
is a must if you want to build a bike for travelling and everyday use.
The 20" wheels have almost no suspension effect, so the frame and
yourself will have a rather rough ride if the street is not smooth.
35x35 mm tubing will work fine. My airbike is made of the same
material. Bending the lower crank is absolutely necessary to gain
enough ground clearance. If you build the bike for racing purposes
leave the suspension but use thicker tubing instead.
The bending of the crank is easy if you have a propane/oxygen torch.
Let me quote Colin Morton from Australia:
> To bend alloy without breaking you must anneal it.
> This is really easy
> 1. Get a bar of soap and rub it onto the alloy where you want to bend it.
>2.Gently heat the alloy until the soap turns black. Let it air-cool for 10+
>minutes
>3.Your alloy is now annealed and will bend easily.
>4. Bend with gentle pressure and if it feels like it is getting firm stop
>immediately and re anneal (reheat).
>Remember aluminium melts at just above 500 deg C and when it gets
>close it becomes a liquid so be careful.
Peter and I made a little different approach. We heated the alloy until
a piece of wood can draw black lines onto it. This is the temperature
indicator. Then the crank gets a chewing gum like consistence and
can be bent WITHOUT force. After bending we let it cool down slowly.
The result seems to be as stable as the untreated crank. Let´s see.
Peter is our crash test dummy for this ;-) He is tall, strong and weighs
around 80kg!
If you do not trust the bent alloy you can as well cut a steel crank at
the right angle and weld it. This is very stable (but weighs the double).
A friend of mine and myself are thinking a lot of building a python-like
bike which is completely foldable. There are some good ideas so far
but it is still in the theoretical phase. Center-steered bikes in general
are
very suitable to be made foldable (see
http://www.airbike.de/bilder/airbike_gefaltet.jpg).
Olaf, we hope to see some real pictures soon and wish you good luck.
A place on my homepage is now reserved for your project.
Jürgen.
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