python - a center-steered lowrider

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

Quoted message said:

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.

bent but not broken,

Juergen.

"juergen" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

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 ;-)

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

Quoted post said:

Originally posted by Juergen
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:

python.de.ttpython.de.ttOpen ↗

Please let me know your opinion about the bike!

bent but not broken,

Juergen.

beetle_deuce <[email hidden]> wrote in message
news:<[email hidden]>...

Quoted message said:

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.

Quoted message said:

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.

python.de.ttpython.de.ttOpen ↗

Hi again Juergen,

Quoted message said:

Quoted message said:

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

beetle_deuce <[email hidden]> wrote in message
news:<[email hidden]>...

Quoted message said:

Hi again Juergen,

Quoted message said:

Quoted message said:

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.

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)!

rowvelo.com27FDRWS.jpgOpen ↗

Warren

Quoth [email hidden] (Warren Berger):
| 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)!
|
| rowvelo.com27FDRWS.jpgOpen ↗
|
| Warren

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

Donn,

Quoted message said:

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.

Quoted message said:

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

More than a bit.

Quoted message said:

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

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.

[email hidden] (Warren Berger) wrote in message
news:<[email hidden]>...

Quoted message said:

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)!

rowvelo.com27FDRWS.jpgOpen ↗

Warren

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" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

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.

[email hidden] (Warren Berger) wrote in message

news:<[email hidden]>...

Quoted message said:

Quoted message said:

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)!

rowvelo.com27FDRWS.jpgOpen ↗

Warren

"Torben Scheel" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

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.

Juergen,

Quoted message said:

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

Quoted message said:

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

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.

[email hidden] (Warren Berger) wrote in message
news:<[email hidden]>...

Quoted message said:

Juergen,

Quoted message said:

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

Quoted message said:

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,

Quoted message said:

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.

l2.espacenet.comviewerOpen ↗

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.

rowvelo.comrowvelo.comOpen ↗

Warren

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.

[email hidden] (Warren Berger) wrote in message
news:<[email hidden]>...

Quoted message said:

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