Baby python

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This bike was built by Dirk Bonné -- rollout 2004-12-01.

It has been the first working 20inch version of the python. Due to the small wheels other geometry than the usual 26inch python is possible, and this bike minimizes self centering effect, without causing wheel flop. This makes the bike very agile, while still being not nervous.

Recently the original baby python got touched up, where the front part got partially redone. The bottom bracket was not straight and this irritated during longer tours, where I could feel the difference between left and right through my knees. Now I brazed the bottom bracket, instead of the previous welding, and now it is straight (and 1cm further away). The main tubing is either 30x30x1.5 or 30x10x1.5. By its own the tubing is not big enough to make a stiff frame, but the front 8x1mm tubing at the front solves that.

The bike is quite light for a home built, with 14kg with everything on, but strong enough to hold against my rough handling. I have many kms on this bike, as I use it daily (can't say how much as I only recently installed a speedometer).

In the winter I use a 5W halogen with a lead accu (14Ah) to get me through the pitch dark passages on my way home.

Geometry Data

- Pivot Angle [°] Trail [cm] Seat Height [cm] BB-Seat Diff. [cm] Ground Clearance [cm] Wheelbase [cm] Weight [kg] BB-FWA [cm] BB-EOS [cm] Turning Circle [m] Front Tubing [mm] Wheel Size [inch] CG [%]
baby python 60 -14 28 20.5 21 111 14 49 74 - 30x10x1.5 20" 20" -

Front Part

Rear Part


The seat is taken away from my old Challenge Twister.


I used to ride with 406-37 width tires (vredestein monti carlo), but I switched to schwalbe big apples 406-50. A much fatter tire with very good rolling properties. Fat tires are really to recommend for small sized wheels! Bumps or holes are much less of a problem.

Building It

Mastering The Bike Log

Not much to say here as I already could ride the flevo before, and the python is not _that_ different. You can see me riding on this video on youtube (I pull a burley solo here, and the camera is mounted onto that):