python - a center-steered lowrider

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juergen

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Apr 4, 2003, 3:05:16 AM4/4/03
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Hi bent-folks,

let me introduce an easy-to-build 2x26" center-steered
lowrider to you.
It took me some time of pre-studies but only 2 weeks of
building-time (I did not spent more than 10 bucks for material).
The python weighs about 17kg fully equipped, the seat height is 32cm.
After some time of learning the center-steering-basics, it is
easy to ride and quite fast.
I ride it daily - even in the urban traffic.

Here is the link to my homepage:

http://www.python.de.tt

Please let me know your opinion about the bike!

bent but not broken,

Juergen.

Nomad

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Apr 4, 2003, 4:51:10 AM4/4/03
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Gadzuks Juergen! How do you steer?

juergen

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Apr 4, 2003, 8:48:23 AM4/4/03
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Nomad <deep...@hotmail.com> wrote in message news:<3E8D558D...@hotmail.com>...

> Gadzuks Juergen! How do you steer?

Hi Nomad,

I must admit, there is no handlebar. But it is not
necessary because the python is steered by feet.
This needs some learning (about 1 week) but then
it works fine ...

Juergen.

http://www.python.de.tt

Hillel

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Apr 4, 2003, 9:46:47 AM4/4/03
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Wow! Cool bike.
Is that a BB and crankarms for the steering joint?

Seth Jayson

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Apr 4, 2003, 10:24:11 AM4/4/03
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That is the coolest, weeeeeerdest thing I've seen in a while. I
imagine there will be some folks over here happy to cut up some
junkers and try that design. If I could weld, I might try.

Sj

>

> http://www.python.de.tt

bentnut

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Apr 4, 2003, 1:10:47 PM4/4/03
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Very COOL! Can you tell us a little more about riding it? How do you start,
stop, turn, etc...

"juergen" <jma...@gmx.de> wrote in message
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Torben Scheel

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Apr 4, 2003, 1:17:40 PM4/4/03
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Great design! And great to see some new(?) thoughts. I might try to copy the
design for my next project - do you feel safe in traffic on the python? I
would expect a bit of anxiety going fast downhill.

Can I -please- use the photos on www.hpv-klub.dk ?

Regards,
Torben

"juergen" <jma...@gmx.de> wrote in message
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harv

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Apr 4, 2003, 3:47:18 PM4/4/03
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Looks pretty cool, but a little lacking in room between the 'nads and the
front tire.

"juergen" <jma...@gmx.de> wrote in message
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Mark Helmus

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Apr 5, 2003, 11:22:15 AM4/5/03
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just brings out a new use for a "bike" cup!

Rob

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Apr 5, 2003, 2:46:12 PM4/5/03
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Yeah, agree it's cool.

If you build it, I would be interested on how you make out.


"Torben Scheel" <torben...@hotmail.com> wrote in message
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Rob

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Apr 5, 2003, 2:49:03 PM4/5/03
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Very cool. I think you could be really on to something here.

What is the rubber flap, on the articulation part of the bike for?

Why do you have the bolt through the rubber for, (looks like folded up inner
tubes), is that for suspension?

Rob.

"juergen" <jma...@gmx.de> wrote in message
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Lewis Campbell

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Apr 5, 2003, 8:32:32 PM4/5/03
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Thats very interesting, Juergen.

The first time I went to your site, all I saw was the 3-D modelling
and did not notice the link to the photos.

You've really done a good job of an interesting looking machine. Did
it take you very long to get used to the steering?

Good luck.

Lewis.

http://tinyurl.com/8vvh
.........................

jma...@gmx.de (juergen) wrote in message news:<d5c88ce6.03040...@posting.google.com>...

Torben Scheel

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Apr 6, 2003, 10:57:44 AM4/6/03
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"Rob" <da...@shaw.ca> wrote in message
news:8oGja.47345$vs.31...@news3.calgary.shaw.ca...

> Yeah, agree it's cool.
>
> If you build it, I would be interested on how you make out.

I'll post experiences here, if I choose to build it. I'm torn between
building a Zephyr lowracer using parts from my old DF racer (ancient Dura
Ace components - 7400 series), and the Python, which would be a fun and
challenging project.

Torben


Joshua Goldberg

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Apr 6, 2003, 11:08:20 AM4/6/03
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Juergen
very interesting bent design, 1st time I saw the python page I only saw the
CAD and did not notice the link to the photos. Once I saw the pics the CAD
made more sense. (forgive this OT)...but being an architecture
groupie...what is the building in the background?
-----------------------------------------

"Torben Scheel" <torben...@hotmail.com> wrote in message
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Paul Milner

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Apr 7, 2003, 12:03:12 AM4/7/03
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jma...@gmx.de (juergen) wrote in message news:<d5c88ce6.03040...@posting.google.com>...

Hi Juergen,
Will you be offering plans for the Python?
Paul Milner

Leendert Prevo

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Apr 7, 2003, 2:09:07 AM4/7/03
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Nice bike !

This steering principle is used also in the
original Dutch Flevobike bike, trike and racer.
For pics see: http://www.ligfiets.net/fietsen
Choose Tempelman - Bike, Trike, Racer. Comments are
in Dutch language.

Comments say that learning time is 1 to 4 weeks, though
some people never learn.

greetings from Holland,
leendert prevo
--

__________________________________________
-<\\\ leendert
|
| @ _ goes by bent
|\\\/ \_
=|=\x/=|=# gaat per ligfiets
____(_)___(_)____________________________
flevobike fifty-fifty

juergen

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Apr 7, 2003, 2:21:55 AM4/7/03
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Thanks a lot for all your positive feedback.
I am glad that you like the python.

I try to answer your questions:

- yes, the steering joint is simply a bottom bracket,
which is welded to the front part. The BB's crankarms
are attached to the middle part of the frame by nuts and
bolts. By opening them, the python can be split in the
middle, which makes storage and transportation easy.
- the rubber block which is attached to the BB is not
really necessary, but it makes steering smoother and
the handling easier.
- the rear suspension is done by cut inner tubes with
a bolt through, thus the strength can be adjusted. It
is similar to a ZOX suspension, but much cheaper.
- the python runs stable even going fast downhill.
- the building in the background is the old hospital
of Erlangen/Germany. Mid 19th century.

have fun,

Juergen.

juergen

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Apr 7, 2003, 10:53:32 AM4/7/03
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> This steering principle is used also in the
> original Dutch Flevobike bike, trike and racer.

That is right. But the ancestor of the python is the
airbike (http://www.airbike.de) and not the flevobike.
I rode the airbike for 7 years and wanted to create a
lowracer-version of it, firstly because it is faster
and secondly because I like to touch the ground with
my hands when starting and stopping so that my feet can
stay on the pedals. (thirdly maybe picking flowers while
riding;-)

> Comments say that learning time is 1 to 4 weeks, though
> some people never learn.

I guess that riding the python is much easier than the
flevobike because it is more stable and the steering
is not that agile. The disadvantage of the python is
the relatively big turning cycle of 7 meters. The bike
loves to go straight ahead...

regards,

Juergen.

Kirt Bowman

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Apr 7, 2003, 11:23:07 AM4/7/03
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Great design verrrrrrrrry cool This is certainly one of the most innovative
home builts I have ever seen. You ought to make plans available I know I
would buy them.

--
Kirt Bowman
24/20 v-rex
r-30 vision


"juergen" <jma...@gmx.de> wrote in message
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Penguinista

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Apr 7, 2003, 11:38:55 AM4/7/03
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Interesting design.

Tips on the photo page: smaller pictures, crop to item of interest,
thumbnails. Was taking way too long to download on my slow connection.

Don

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Apr 8, 2003, 2:03:59 AM4/8/03
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What is the ground clearance? I know someone who built a low-racer
based on a famous (forgot the name) design but he could not ride over
speed bumps.

The pictures were great. Don't crop them. I have to disagree with a
previous post. Yes, they are very slow to load but the scenery is
fantastic and a point of interest all by itself. What a cool place
to ride around. Would love to ride there on my Zak. Nothing in front
of me but the world. Don

juergen

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Apr 11, 2003, 2:33:35 AM4/11/03
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> What is the ground clearance? I know someone who built a low-racer
> based on a famous (forgot the name) design but he could not ride over
> speed bumps.

Ground clearance is 7 cm only. This is not very much.
I got stuck 2 times until now (a quite funny experience).
One curbstone and one times off-road.

A material list and a building plan for the python will
be available on http:/www.python.de.tt within the next
3 weeks.

Torben Scheel

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Apr 11, 2003, 4:03:44 AM4/11/03
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"juergen" <jma...@gmx.de> wrote in message
news:d5c88ce6.0304...@posting.google.com...

>
> A material list and a building plan for the python will
> be available on http:/www.python.de.tt within the next
> 3 weeks.

Great! I'll be ripping anything for www.hpv-klub.dk - with your permission,
off course ;-)


beetle_deuce

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Jun 23, 2003, 12:42:25 PM6/23/03
to
Juergen wrote:
> Hi bent-folks,
> let me introduce an easy-to-build 2x26" center-steered lowrider to you.
> It took me some time of pre-studies but only 2 weeks of building-time (I
> did not spent more than 10 bucks for material). The python weighs about
> 17kg fully equipped, the seat height is 32cm. After some time of
> learning the center-steering-basics, it is easy to ride and quite fast.
> I ride it daily - even in the urban traffic.
> Here is the link to my homepage:
> http://www.python.de.tt/http://www.python.de.tt

> Please let me know your opinion about the bike!
> bent but not broken,
> Juergen.

Hi!

Great looking bike, very creative! My initial thought was that using a
front fork for the rear wheel looked a little weak. On reflection I may
have changed my mind - after all, on a conventional bike the front fork
has to resist large bending moments in the form of braking forces, in
addition to bike/rider weight. Have you considered these things? It's a
little hard to see on the photos, but how have you welded the fork to
the square tube - any reinforcement, and does the fork tube continue
inside the square section? How does it seem to be holding up?

regards, Magnus


--
>--------------------------<
Posted via cyclingforums.com
http://www.cyclingforums.com

juergen

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Jun 26, 2003, 11:19:39 AM6/26/03
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beetle_deuce <usenet...@cyclingforums.com> wrote in message news:<3ef732a1$1...@news.chariot.net.au>...

>
> Hi!
>
> Great looking bike, very creative! My initial thought was that using a
> front fork for the rear wheel looked a little weak. On reflection I may
> have changed my mind - after all, on a conventional bike the front fork
> has to resist large bending moments in the form of braking forces, in
> addition to bike/rider weight. Have you considered these things? It's a
> little hard to see on the photos, but how have you welded the fork to
> the square tube - any reinforcement, and does the fork tube continue
> inside the square section?
>
> regards, Magnus


Hi Magnus,

first let me thank for the compliments.

The fork tube continues inside the square tube and there are
trenches in the square tube through which the weldseam connects
the fork tube with the outer square tube. This should do.

Additionally there is a rear suspension which protects the fork
from bumping too much.

> How does it seem to be holding up?

Sorry Magnus, I do not understand what you mean. Can you explain?

BTW: Meanwhile I started a mailing list for homebuilders, added some
more fotos to the python homepage and wrote a short intro about
the bike's history.

regards, Juergen.

http://www.python.de.tt

beetle_deuce

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Jun 26, 2003, 4:30:02 PM6/26/03
to
Hi again Juergen,

>> How does it seem to be holding up?
>Sorry Magnus, I do not understand >what you mean. Can you explain?

I just wondered if the rear fork still looks strong after the first 2500
km? Any wear, or still ok? I have a friend who works in a bike shop, and
we're feeling a little inspired.... We only have round tube in stock,
and will probably have to rethink the rear set-up a little.

cheers, Magnus

juergen

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Jun 27, 2003, 2:59:50 AM6/27/03
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beetle_deuce <usenet...@cyclingforums.com> wrote in message news:<3efb5c7a$1...@news.chariot.net.au>...

> Hi again Juergen,
>
> >> How does it seem to be holding up?
> >Sorry Magnus, I do not understand >what you mean. Can you explain?
>
> I just wondered if the rear fork still looks strong after the first 2500
> km? Any wear, or still ok? I have a friend who works in a bike shop, and
> we're feeling a little inspired.... We only have round tube in stock,
> and will probably have to rethink the rear set-up a little.
>
> cheers, Magnus

Ah, now I understand you.

There is no wear so far and everything works fine.

Round tube for the frame should do as well. Just a
little more pottering ...

good luck,

Juergen.

Warren Berger

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Jun 27, 2003, 11:34:52 AM6/27/03
to
Juergen,

Welcome to the world of truly wacky bikes!

If you think negative trail (NT), front-wheel-drive (FWD),
front-wheel-steered (FWS) bikes are challenging...try NT, FWD,
rear-wheel-steer (RWS)!

http://www.rowvelo.com/images/27FDRWS.jpg

Warren

Donn Cave

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Jun 28, 2003, 12:00:24 AM6/28/03
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Quoth eld...@cstone.net (Warren Berger):

Looks good, how does it feel? Does that man look a little
nervous or something? I like the short chain line you get
with front wheel drive, seems like it has potential to be
more efficient. But last I heard, it tends to be a bit hard
to operate.

I'm not sure Juergen's thing is front wheel steer. It has
been a while since I looked at the picture, but the way I
remember it, the steering axis was between the wheels -
with yours too?

Donn

Warren Berger

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Jun 28, 2003, 3:24:50 PM6/28/03
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Donn,


> Looks good, how does it feel?

It was very efficient climbing, but was not very relaxing on fast
descents. The steering axis angle, and steering ratio were a
compromise between high speed stability and maneuverability.

> But last I heard, it tends to be a bit hard to operate.

More than a bit.

> I'm not sure Juergen's thing is front wheel steer. It has been a while since I looked at the picture, but the way I remember it, the steering axis was between the wheels - with yours too?

Most bikes have two sub units, which turn relative to each other. If
you sit on the rear unit, and turn the front unit, as with Juergen's,
it is FWS. If you sit on the front sub unit, and turn the rear unit
(on these, the steering linkage must be reversed for normal steering
sense), as with mine, it is RWS. It does not matter where the
steering axis falls. This only determines if it has positive or
negative trail.

Some bikes actually have three sub units. You sit on the middle one,
and the two at either end turn. These are two-wheel-steered!

Warren

juergen

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Jul 3, 2003, 5:18:45 AM7/3/03
to
Hi Warren,

I saw, that you have a lot of experience with NT bikes.
RWS is not my thing because it is not safe.

Did you notice that the python's NT has no negative effect
on steering safety because of two effects:

- the riders weight pulls the front part
automatically in a straight ahead position

- the steering damper enhances this effect and
additionally prevents the front wheel from
wobbling

I have about 3000 km of experience with the python and
I appreciate it as a fast and safe bike.


Regards, Juergen.


eld...@cstone.net (Warren Berger) wrote in message news:<930c70dc.03062...@posting.google.com>...

Torben Scheel

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Jul 3, 2003, 7:26:22 AM7/3/03
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Hi Juergen.

Have you seen the post about a leg steered recumbent for a guy without arms?

Do you think the Python would work for him with a "foot-brake" and another
seat?

Regards,
Torben


"juergen" <jma...@gmx.de> wrote in message

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juergen

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Jul 3, 2003, 10:11:30 AM7/3/03
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"Torben Scheel" <torben...@hotmail.com> wrote in message news:<3f040fce$1...@news.carlbro.dk>...

> Hi Juergen.
>
> Have you seen the post about a leg steered recumbent for a guy without arms?
>
> Do you think the Python would work for him with a "foot-brake" and another
> seat?

Torben,

I see the python more as a racing bike than as a bike for
everyday use. For the high velocities one can reach, I think a
foot brake is not a good idea.

hej hej, Juergen.

Warren Berger

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Jul 3, 2003, 12:51:45 PM7/3/03
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Juergen,

> Did you notice that the python's NT has no negative effect on steering safety

> I have about 3000 km of experience with the python and I appreciate it as a fast and safe bike.

It sounds great. How fast have you gone on curvy, steep mountain
desents? I found them very scary on my FWD, RWS.

Warren

juergen

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Jul 4, 2003, 3:34:57 AM7/4/03
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My fastest descent was about 60 km/h. But the road was quite straight.
The lowracer gains a lot of speed downhill which makes me a bit
scary, so I tend to brake anyway.

How about your RWS bike?

Juergen.


eld...@cstone.net (Warren Berger) wrote in message news:<930c70dc.03070...@posting.google.com>...

Warren Berger

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Jul 4, 2003, 2:13:56 PM7/4/03
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Juergen,

> How about your RWS bike?

As I said, I found them very scary on my FWD, RWS.

If the Python is as stable as you say, you might want to consider a
rowbike version. No pedal steer with a rowbike.

Check out Paul Francois' design from 1944.

http://l2.espacenet.com/espacenet/viewer?PN=FR890589&CY=gb&LG=en&DB=EPD

It looks very similar to the Python. You could use a bottom bracket
and cranks for the hanging pendulum, like you used for your steering
pivot. Slide about 46 cm of rectangular tubing over the cranks to
make the hanging pendulums. The handlebar stem should be about 46 cm
long as well, and attached to the front section (turning with the
front wheel). It should be a yoke, straddling the front wheel. Use
an 11-34T cassette, and 406 mm wheels, and the gear range will be
about perfect!

This would be one sweet rowbike. Trust me! If you have any questions
about this design, just ask.

http://www.rowvelo.com/

Warren

juergen

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Jul 5, 2003, 3:05:13 AM7/5/03
to
Thanks Warren,

I always thought of an additional hand-driven acceleration.
Steering is by feet and so the hands are without any use most
of the time.
When I want to ride fast I use my hands to push the
knees which makes about 4 km/h more speed.

Regards, Juergen.


eld...@cstone.net (Warren Berger) wrote in message news:<930c70dc.03070...@posting.google.com>...

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