[python] Request from France
- From: Jürgen Mages <jmages@xxxxxx>
- To: "Python Malinglist" <python@xxxxxxxxxxxxx>
- Date: Sat, 17 Jul 2004 03:29:41 +0200
Yesterday I received mail from Ghislain, France.
I would like to share it with you:
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Hello Jurgen,
Congratulations for your achievement and your effort to promote the
Python, and thanks for sharing it for free !
I've built 2 recumbents, bentech make it yourself US design, I did'nt
do the welding myself, I had to subcontract it.
We enjoy the bikes very much, the wheels are 20", 26", no suspension.
For touring on French roads it's ok. I use to ride holding the
handlebar with one hand only, the other one resting freely.
Looking around for my new homemade recumbent, I flashed immediately on
your Python : brilliant, simple, low cost, achievable, no hands at all
this time, plus the personal challenge to get the balance !
(One point remains unclear : Behaviour of the Python self steering at
low speed, on flat ; at (very) high speed downhill, and uphill at low
speed when pushing hard on the pedals to keep the thing on balance and
moving ,say 6 km/h ?)
Capitalizing on Bentech experience, my personal requirement about the
overall weight of my new homemade bike is : Use a flawless existing
design, overall weight should not exceed 10kgs - carbon fiber, or
aluminium, to be used instead of steel, no suspension is acceptable
(for me).
I then started to think about the way to make it.
Then came the Danish python, no brakes and one Flevobike pivot !
Looks simple and neat, (but, please, what is the rubber silent block
for ?). Looks easy to assemble to a pipe...Why not have a go for it
as it is available ? Being not an engineering expert ; I'd rather buy
something which works well than start hasardous experiments.
Then came the Airtrike : oh! oh!..
Forward part made of one single piece of tube, carbon and aluminium
with the canti drive ! Looks ideal !
Canti drive from Air Trike ? Reply : Available for 95$ each, if I take
minimum of 2 .
Question mark about the self steerint system of the Airlite trike : I
suspect the system works only if resting on a two wheels aft part ; I
doubt it can be adapted to classic two wheels recumbent. Wrong or right
guess ?
The picture of my new homemade bike now gets clearer :
Forward part as Airlite trike, single carbon/aluminium pipe with a
cantidrive, and a Flevo steering pivot.
Aft part, another single carbon/alu pipe and a cantidrive to get rid of
the fork. Seat, carbon with foam, or aluminium pipe with mesh .
But, does this make sense ? Question for the engineers : if cantidrive
used only forward, is the off center wheel compatible with the balance
?
If cantidrive used forward and aft, are the off center wheels
compatible with the balance of the whole unit ?
Your comments will be welcomed !
You are working now on a new pivot with conical rollers (?) will you
make the design available to all of us, when it's ready and thoroughly
experimented ?
Cordially,
Ghislain Pillet,
Antibes, France.
--------------------------------------------------------------
And here is what I answered:
Hi Ghislain,
> Behaviour of the Python self steering at
> low speed, on flat ; at (very) high speed downhill, and uphill at low
> speed when pushing hard on the pedals to keep the thing on balance and
> moving ,say 6 km/h ?)
Low speed and uphill is absolutely no problem at all. High speed is
a matter of self-confidence and training. With my first python I
could reach 65 km/h. With my third one, which is quite new, I came
to 55 km/h until now.
> Looks simple and neat, (but, please, what is the rubber silent block
> for ?).
The rubber is absolutely necessary for the flevobike and the
airbike. It is a steering damper that inhibits wheel flop.
The python does not need this, because it has no wheel flop.
Nevertheless Torben uses this steering damper. He says that
it makes handling (e.g. pushing) easier.
> Question mark about the self steerint system of the Airlite trike : I
> suspect the system works only if resting on a two wheels aft part ; I
> doubt it can be adapted to classic two wheels recumbent. Wrong or right
> guess ?
The steering system of the trike is a pivot made of two
elastomere blocks. One at the back of the seat and one
under the seat.
I doubt that this is an acceptable solution for high speed as
well as for a two wheeler, because there is no rigid pivot,
resulting in too much wobbling.
> The picture of my new homemade bike now gets clearer :
> Forward part as Airlite trike, single carbon/aluminium pipe with a
> cantidrive, and a Flevo steering pivot.
> Aft part, another single carbon/alu pipe and a cantidrive to get rid of
> the fork. Seat, carbon with foam, or aluminium pipe with mesh .
> But, does this make sense ? Question for the engineers : if cantidrive
> used only forward, is the off center wheel compatible with the balance
No problems expected here. As the balance has to be learned anyway,
your cerebellum will compensate this. For the steering pivot I
prefer the brazilian solution from Eduardo.
> If cantidrive used forward and aft, are the off center wheels
> compatible with the balance of the whole unit ?
I would build one cantidrive to the right and the other to the
left side to achieve better centering.
> You are working now on a new pivot with conical rollers (?) will you
> make the design available to all of us, when it's ready and thoroughly
> experimented ?
Of course ;-)
Regards from Jürgen.
PS: I posted this to our mailing list (python builders), because s.o.
might be interested in it. Hope you do not mind. If you want to
join the list you are welcome.
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