[python] Re: let us compare

Hello,

it is very interesting to read about the theoretical basis of the python again. 
Jürgen always recommends a steering angel around 67°. If  I remember right the 
reason was, that a lower angel causes wheelflop and a steeper angel makes the 
bike unridable, because the selfcentering effect disappaers. In the projecct 
survey page are a lot of pythons with lower angels down to 60°. Is this 
possible, because the riders are so heavy or the front part is so light, that 
no wheelflop happens? Is the conclusion for me (1,74m tall, 70kg) to aim at a 
shallow steering angel for great selfcentering effect but a light front fame to 
avoid wheelflop? Is it right, that a bike with small wheels in general allows a 
lower steering angel because the COG of the front frame is not so high over the 
pivot point like on a bike with large wheels?

In the weekend I cut out the complete front part of the front frame, changed it 
for the new crank, welded everything together again. Then had the first longer 
trip along the dyk about 15 km. I felt it easier to go a little bit uphill or 
against the wind than downhill or downwinds. In general  get scared in higher 
speeds. Does this mean: no PSI problems, but not enough selfcentering effect? 
Or is it too early to make any conclusions?
Your advices are welcome.

Lutz
> -----Ursprüngliche Nachricht-----
> Von: python@xxxxxxxxxxxxx
> Gesendet: 29.10.07 18:24:49
> An: python@xxxxxxxxxxxxx
> Betreff: [python] Re: let us compare


> 
> Thanks Dirk,
> 
> very enlightening!
> 
> A common problem in comparing pythons is that there is no standard 
> building plan. I was quite surprised how different even the four 26" 
> pythons were that I have tried. Despite their geometry was quite 
> similar, each felt different and it took me about 20 minutes till I got 
> used to them. No wonder that different wheel sizes have even more influence.
> 
> > One difference with the flevo / python is the pedal induced steering.
> > pedal induced steering is the slight wobble of the front bottom bracket
> > in the cadence of pedalling. It was practically unnoticable on the flevo.
> > It does amount to much on my python in terms of steering (I am guessing
> > about 0.5degrees), but still I find it not very estetical. May be a 26"
> > python has less PSI - my proficiency on Serges python was not good
> > enough to judge that.
> 
> I do not notice any PSI while riding, but I recall that when I switched 
> from python to airbike the latter felt less wobbly. The airbike always 
> gave me the impression like riding on rails. I guess, the flevo is 
> similar and I think the reason is the lower steering pivot angle of both 
> airbike and flevo:
> 
> http://upload.wikimedia.org/wikipedia/de/5/50/Knicklenker.png
> 
> Groetjes,
> Jürgen.
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