[python] AW: Re: The Python Patrick Introduced in February 2011

Hi Bob,
while a trike promises an easy start, I dont think it is necesarily the better 
option.
On a dry streets and with high speeds in mind, a two wheel python might be the 
better option. 
Specialy cornering at high speed is less tricky with the bike.

Learning to ride a two wheel python will take some effort and will go with some 
bruises. Having the seat low, to allow both hands to touch the ground in the 
normal sitting position, makes learning easier. In any case make your first 
steps somewere away from the traffic!

I ride my python trike only in Winter, switching back to two wheels as soon as 
the snow is gone!

BR
Gerald




-----Ursprüngliche Nachricht-----
Von: Bob's DotMac <robert.holliday@xxxxxxx>
An: python@xxxxxxxxxxxxx
Gesendet: Montag, 20. Februar 2012 21:34:57 GMT+00:00
Betreff: [python] Re: The Python Patrick Introduced in February 2011

Patrick//

        Thanks for the thoughtful response.  I have a feeling that I might want 
to focus on a trike.  I'll go back to the mail lists and do some more 
research/homework.  

best regards, 

Bob


On Feb 20, 2012, at 12:13 PM, Patrick van Gompel wrote:

> Hey Bob,
> 
> I think you are talking about this Python: 
> http://cycle.free-creativity.com/images/python2.jpg
> That was the bike I used to learn to drive a Python. I used it for about half 
> a year and then took the front part to make a Python trike. So I didn't use 
> it since.
> I could cycle quite well with it, but there were some situations when I 
> didn't feel secure. Like on some bumps, sharp corners or loose dirt. That 
> wasn't the bike I think, but my lack of experience.
> Pythons have the tendency to slip when going uphill. On a good surface you 
> might not notice anything, but when the road is wet or muddy you might run 
> into problems when going uphill.
> 
> > o How is it working out? Are you satisfied with the design? Have you 
> > modified the design? 
> No, I am not that easy to satisfy when making designs. When I took the front 
> end apart to use it for the trike, I noticed some small cracks in the welds. 
> The rear is really strong I think with the triangular design, but the front 
> is not. The two front tubes that go left and right of the front wheel are 
> rather long. So there is quite some force on the joint (connection pivot 
> point - front tubes). The design was easy to build, but not so strong. To fix 
> this for my trike I welded some extra metal to support this joint. You can 
> see that in this picture: 
> http://cycle.free-creativity.com/images/pythonjet9.jpg (just left of the 
> handle bar). It does the job, but I would really prefer to make a complete 
> redesign with a triangular front part that is both stronger and lighter.
> Another thing I would do differently is the mudguard. It works ok for keeping 
> the dry dirt away from your trousers, but when it is rainy or the road is 
> covered with snow, the splash against the mudguard will make your trousers 
> messy nonetheless. So I would go for a more enclosed option like other riders 
> on this list have done. Though, even more enlcosed so that the splash won't 
> go onto the chain/gears.
> I would change a few other things: disc brakes, Rohloff, going to 24" (since 
> I am a bit close to the front wheel, as my lenght is about 174cm), other more 
> ergonomic handle bar position etc etc...  In short: a first design is hardly 
> ever perfect.
> 
> > o Do you have any thoughts on load carrying capability? Could it handle a 
> > 90 kg rider? Is the design specific to rider weight? 
> As above, the joint was a weak spot in my design. I think a triangular design 
> -like the rear part- is the way too go, but other people might think 
> differently. For home builders it's not the easiest...
>  
> > o How does it handle at higher velocities? Say 50 - 70 kph downhill?
> I don't have much experience with high speeds on that Python. I think 30km/h 
> was the max I did by pedalling. I live in The Netherlands and we don't have 
> hills around here to test high speeds without pedalling. With a very strong 
> wind in the back I think I went with a speed of about 50km/h (highest gear) 
> on my python trike, and I must say that I felt much safer than with 30km/h on 
> the two wheeled Python.
> There are riders that have far more experience with high speeds than me. As 
> far as I know it is possible, but (by far?) not as easy as on a recumbent.
>  
> > o Do you have any thoughts on using disc brakes for this Python design? Do 
> > you use the front brakes at all?
> I am not sure about disc brakes on this design. My next design will have 
> them, but I don't know the right positions for the calipers yet. I have no 
> idea whether they would be close to the front tubes.
> I don't have rear brakes. I think I should for safety and slippery roads, but 
> I haven't really felt the need so far. Remember: brakes on the front do most 
> of the job, not the rear's.
> 
> > Any insight would be helpful. I'm considering having a local (Seattle, WA 
> > US) stainless fabricator put the frame together. Will probably stick with 
> > 26" wheels.
> If you want to use my design, I must add that I put it online for people to 
> give ideas or use it for making their own design. I wouldn't recommend to use 
> it 1 on 1 and give the design to a company to build it. For example: the 
> shapes are not all neatly connected and there are overlapping parts. Another 
> thing is that I would strongly suggest to change a few details, like some 
> more space between derailleur and axle point for better release of the wheel 
> and maybe some other things I forgot at the moment.
> 
> Anyway, quite a long email but I hope it gives you a better idea about the 
> bike.
> I don't have that much experience with a two wheeled Python, but if you are 
> really after high speeds and going uphill I would ask some riders with more 
> Python-cycling-time than me. They might give you a better idea if a Python is 
> what you want for your purpose.
> 
> If I can help you with anything else; just ask.
> Patrick
> 
> 
> > From: robert.holliday@xxxxxxx
> > Subject: [python] The Python Patrick Introduced in February 2011
> > Date: Mon, 20 Feb 2012 10:52:31 -0800
> > To: python@xxxxxxxxxxxxx
> > 
> > Hi Folks//
> > 
> > This is my first post. Hope I get it correct. I currently ride an SWB 'bent 
> > (HP Velo Street Machine). Do a lot of hill riding with it. Uphill is slow 
> > and downhill is fast. Saw the Python and became interested - perhaps the 
> > short distance to the road while falling was attractive. I've had my share 
> > of encounters with the road. I wonder if Patrick could provide some updates 
> > and insight on his stainless Python? 
> > 
> > o How is it working out? Are you satisfied with the design? Have you 
> > modified the design? 
> > 
> > o Do you have any thoughts on load carrying capability? Could it handle a 
> > 90 kg rider? Is the design specific to rider weight? 
> > 
> > o How does it handle at higher velocities? Say 50 - 70 kph downhill? 
> > 
> > o Do you have any thoughts on using disc brakes for this Python design? Do 
> > you use the front brakes at all? 
> > 
> > Any insight would be helpful. I'm considering having a local (Seattle, WA 
> > US) stainless fabricator put the frame together. Will probably stick with 
> > 26" wheels. 
> > 
> > best regards, 
> > 
> > 
> > Bob
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