[python] Re: let us compare
- From: dirk.bonne@xxxxxxx
- To: python@xxxxxxxxxxxxx
- Date: Mon, 29 Oct 2007 14:12:06 +0100
Hi,
Sorry for the late reply but I have been away.
Jürgen Mages wrote:
> Hello Brian,
>
> > Please give us the typical characteristics of the 3 principle
> > center-steer bikes:
> > Airbike
> > Flevobike
> > Python
>
> Consider that I have ten-thousands of kilometers experience on both
> airbike and python, but only several hundred on a flevobike. Better to
> ask real Flevonauts like Olaf or Dirk.
I have good experience with flevo (20" flevo racer variant), and 20"
python (my own bike).
The 20" flevo is:
http://dirkb.dnsalias.net/image/flevo/flevo01.full.jpg
and the python can be view amongst the project list of Jürgen (it is the
baby python).
I have ridden on the 26" python of Serge for some 14kms (one evening),
and know the monty (16" python) from several rides. And I think in
comparing the flevo / python one should really differenciate between
python_26, python_20 or python_16. They have all a different wheelbase
and trail and make a different bike.
When trying Serges python (26") I noticed it drives more layed back:
after the initial difficulties with the bike, my impression was that it
worked quite well -- I should ride more to really know. Driving my own
python (20") on the other hand has a more agressively touch: taking
U-turns on small roads works very well (something not all "normal"
recumbents can do). And the monty (16") just cries out to fool around
with doing 8-er turns.
Mostly the turning behaviour comes from the different self centering
force of the python. My own bike I can sway the front part so far that I
hit the a physical limit (the handlebars hit the seat frame). On Serges
bike the self centering force gets to big for that so it is difficult to
do that.
Jürgen has compared the 26" python with the airbike. I can compare my
20" python with my 20" flevo racer. A noriginal flevo has two settings,
by changing the height of the rear damper. My own flevo could not do
this and corresponds in geometry to the lower setting (the less agile
setting).
Ok here comes my take of it:
>
> > How do they compare:
>
> > turning circle and sudden avoidance of obstacles etc
>
> A clear ++ for flevo and airbike. I can survive with my python in the
> city traffic, but it is definitely not its favourite terrain. However
> bumping over an obstacle e.g. a stone has far more consequences on an
> airbike/flevo than on a python concerning stability and road impact.
My 20" python has a smaller turning circle then the 20" flevo. Avoiding
obsticals is easier/faster. There are two causes for these effects:
* The flevo has a rubber spring in the steering, which you have to fight
to turn the bike.
* My own flevo has a heavy front part and I always felt that swaying it
took more time. This is probably different on a "flevo bike".
On my python I have survived front wheel slips on icy roads, where I am
convinced I would not have been able to recover on my flevo.
I must say that I like riding in Town with my python (and also on my
flevo), but that is probalbly more of an matter of view.
>
> > Ease of building
>
> The airbike is very difficult to build. For the flevobike you have
> detailed building plans, whereas building a python is always from
> scratch. However python building is less challenging and costly as
> flevo-building I guess.
>
Was about the same. Flevo you can buy some nice parts (steering joint,
rear axle, etc..). My own python is more simple because no suspension.
Otherwise no real difference.
> > Up hill
>
> A clear ++ for the python. Airbike/flevo tend to loose traction very
> easily.
Yes. Much better.
>
> > Down hill at speed
>
> The other way round: Pythons are bitchy at +50 kph (at least for me)
> wheras airbikes/flevos even gain stability with the speed. Going fast
> (80kph) with the airbike felt like riding on rails. However I had an
> unsuspected accident with the flevo at 40kph which caused me to
> abandon this bike.
My own top speed on the python at the moment is 63kmh. Not further
explored yet.
I haven't ridden my flevo for about 4 years now, and I do not remember
how troublesome high speed was (I certainly had similar speeds on my
flevo). However, I talked to a friend of mine (Mike who is also in the
project list) who recently switched from 26" flevo racer to 20" python,
and he's opinion is that on the flevo it was easier (he has had speeds
up to 60kmh after a few weeks of riding his python).
>
> > Cross country over grass, sand and/or mud
>
> Clear +++ for the python here. I love going off-road. Especially with
> the helps of your hands on the ground you can master difficult trails
> without having to unclip your feet.
Flevo slips to much. Python is better, but worse then any other
recumbent IMO. Probably 26" wheels will help a lot.
>
> > ease of dismantling for compact travel by car or rail
>
> This is very construction dependant. The Monty built by Olaf folds
> rather small (see his page). The airbike also folded nicely (see my
> foto on the airbike site) and I guess the flevo also folds nicely and
> quick. Midsteerers are generally very suitable for folding.
My flevo used the standard steering joint and folded easier then my own
python, but it was still a bother. To put the steering axle through the
rear part, you have to struggle to pieces of metal with wheels under
them. I seldom came clean out of this operation.
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.
hope this helps
Dirk
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