Python Projects Survey

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 [%]
stokid 57.5 -17 28 25 - 178 18 49.5 - - 30x10x1.5 20" 26" -
Dirk 60 -14 28 20.5 21 111 14 49 74 - 30x10x1.5 20" 20" -
Ghislain_1 60 -14 29 20 22 100 13 46 75 - 30x10x1.5 20" 20" -
Borm 60 -14 31 23 26 100 18 50 70 - 30x15x1.5 20" 20" -
Ghislain_2 60 -14.5 30 - - 106 13 - - - 45x23x2.0 20" 20" -
Nobuo 60 -16 20 17 4 115 - 40 63 - - 16" 16" -
Gavin 60 -17 28 12 7.6 88 - - 67 4 25x13x1.5 16" 16" -
Pajton 60 -17 30 28 - 95 - - - - - 20" 20" -
Mike 60 -18 25 20.5 15.5 111.5 15 51.2 78 - 13x1 10x1 20" 20" -
Martin 60 -20 32 8 8 110 15 36 67 - 13x1 20x1 20" 20" -
Jukka_1 60 -25 30 10 - 130 17 - - 4.5 30x15x2.0 26" 28" -
Jukka_2 61 -21 24 14 14 140 19.7 41 80 5 30x15x2.0 24" 28" -
Monty 62 -17 27 14 15 88 11 47 66 - 30x10x1.5 16" 16" -
Jaculus 62 -20 28 17 17 138 13 37 71 - 30x15x2.0 27" 27" 61
Gerald 20 62 -22 27 31 14 90 13.9 53 - 1.5 50x20 alloy 20" 20" 46
pythoon 62.5 -17.5 31 17 - 162 18 49.5 - - 30x10x1.5 20" 20" -
Piko 63 -14 34 15 14 138 16 42 65 - 20-150 20" 26" 61
Marcel 63 -25.4 29 10 5 117 12 - - - 51x13x1.6 26" 16" -
Serge 63 -27.4 28.5 25.5 10.4 125.3 16 40 74 - 13x1 10x1 26" 26" -
Patrick 64 -26.5 34 12 13 120 15 40 73 2.5 40x10x2.0 26" 26" 62
Torben 65 -27 29 21.5 17 134 13.5 38 77 7 30x10x1.5 27" 27" -
Worm 65 -28 20 29 12 128 16 38.5 69.5 4.2 30x20x2.0 26" 26" -
Elias 67 -21 21 18 19 138 13.4 36 35 - 16x1.25 13x1 26" 26" -
P4 67 -24 20 23 12 113.5 14 34 63.5 4 40x10x1.5 24" 24" -
P1 67 -27 31 19 7 129 19.8 38 70 6 30x20x1.5 26" 26" 63
P3 67 -27 30 21 15 129 19.8 41.5 73.5 5 40x10x1.5 26" 26" 63
42 67 -27.6 24.5 29.5 11.5 138 18.7 40 79 - 40x10x1.5 26" 26" -
jmaier 67 -31 40 5 - 120 15 42 - - - 27" 27" -
Gabriel 68 -29 28 18 16 130.5 15 38 72 - 40x10x1.5 26" 26" -
P2 68 - 29 17 - 127 16.5 42 75 - 30x20x1.5 26" 28" -
BHP 68 - 34 9 7.6 107 16 - - - 51x13x1.6 26" 20" -
Laurent 69 -30 20 26.5 11 114.5 13 37 72.5 2.5 35x20x1.5 26" 26" 58
Ray 70 -28.5 40 7 - 109 16 - - 6 - 26" 26" -
Gert 71 30 29 - 12 130 19 - - - 35x15x1.5oval 26" 26" -
Sucuri - - - - - - - - - - 30x20x0.9 26" 26" -

stokid

stokid

Roll-out 2011-10

Follower of the pythoon

Video

Gerald 20

Gerald 20

Roll-out 2011-02

Alloy frame

Martin

Martin

Roll-out 2009-12-02

2011-02-14 Mileage 3.500 km

Patrick

Patrick

Roll-out 2011-02
pythoon

pythoon

Roll-out 2010-04

Video 1

Video 2

Elias

Elias

Roll-out 2010-03

Gert

Gert

Roll-out 2009-09

Piko

Piko

Roll-out 2008-08

First Hungarian Python

Video

Serge

Serge

Roll-out 2007-07

2009-09-07 Mileage 2.561 km

Max Speed 65.7 km/h

Serge's page

Mike

Mike

Roll-out 2007-07
Jaculus

Jaculus

Roll-out 2007-04-03

2007-09 Mileage 100 km

42

42

Roll-out 2006-12-15 (42 hours building time)

Z-Frame by Stephan Schöling

Gavin

Gavin Katts

Roll-out 2006-10-01

First South African Python

Borm

Thorsten Borm

Roll-out 2006-04-22

12 mm rod-end bearings

2006-10-10 Mileage 500 km

Ghislain 2

Ghislain 2

Roll-out 2006-03-30

Aluminium frame

2007-08 mileage 5.000 km

Nobuo

Nobuo

Roll-out 2006-02-08
Jukka_2

Jukka 2

Roll-out 2005-11-18
Pajton

Pajton

Roll-out 2005-11-14
PC2

PC2

Roll-out 2005-10-06
Gabriel

Gabriel

Roll-out 2005-06-15

2009-09-07 Mileage 26.000 km

Ghislain 1

Ghislain 1

Roll-out 2005-05
Monty

Monty

Roll-out 2005-04-29

2006-10-10 Mileage 1.000 km

Ray

Ray

Roll-out 2005-04
Laurent

Laurent

Roll-out 2005-02-05
Marcel

Marcel

Roll-out 2005-01-13
BHP

BHP

Roll-out 2005-01-05 (20 hours building time)
Dirk

Dirk

Roll-out 2004-12-01

2009-09-16 Mileage 30.000 km

Max Speed 67 km/h

Worm

Worm

Roll-out 2004-11-17 (14 hours building time)
Jukka_1

Jukka 1

Roll-out 2004-11
P4

P4

Roll-out 2004-08-02 (30 hours building time)

2007-09-20 Mileage 3.000 km

Jürgen Maier

Jürgen Maier

Roll-out 2004-07
Torben

Torben

Roll-out 2004-06-14
P3

P3

Roll-out 2004-04-22 (40 hours building time)

2009-09-07 Mileage 26.000 km

Max Speed 50 km/h

Sucuri

Sucuri

Roll-out 2004-04-01
P2

P2

Roll-out 2004-02-04 (41 hours building time)
P1

P1

Roll-out 2003-02-24 (60 hours building time)

2009-09-07 Mileage 12.000 km

Max Speed 50 km/h



illustration

Pivot Angle

The angle of the steering pivot should be around 60 degrees. Angles bigger than 70 deg. will make the bike nervous, whereas very shallow angles result in increased wheel flop and huge turning circles (This was the major drawback of former center-steered lowracers with positive trail).

Trail

Before you raise any objection against the negative trail of the pythons, have a look at Frame Geometry Page.
The destabilizing effect that NT normally has on dynamic bike behaviour is satisfactorily compensated by the "hanging pendulum" effect and gyro forces.

Seat Height

The seat height is measured at the lowest point of the seat. When building the python, ensure that you can reach the ground with both hands. Riding this bike is only half the fun when you cannot reach the ground. E.g. I never have to unclip my shoes when stopping.

BB-Seat Diff.

An important value for the efficiency of the pedalling force and the air drag. For very racy riders, values around 35 cm are ok. For moderate riders 22 cm are good.

Ground Clearance

One problem of the P1 was its low ground clearance of 7 cm. Especially when riding over curbstones or roots it regularly hit the ground. All later versions have better clearance. 10 cm is the minimum I would recommend for daily usability. If you ride a lot in the cities and offroad then it should be 15 cm.

Wheelbase

The WB should be as short as possible for a small turning circle. Limiting factors are the seat angle and the travel of the rear suspension.

Weight

Of course, the lesser the better. But stability and stiffness of the frame should not suffer.

BB-FWA

The distance between bottom bracket and the front wheel axle is crucial for the chainline. Try to achieve values bigger than 40 cm. If you are below 40, then better use smaller wheels or shorter cranks. For the sake of a maximized BB-FWA, the distance FWA-steering pivot should be minimized.

BB-EOS

This is the distance between the bottom bracket and the front edge of the seat. This measurement corresponds to the rider´s inseam length. As a rough calculation I use inseam minus 13 cm (for 170 mm cranks).

Turning Circle

Just a theoretical value. The TC is twice the turning radius. To measure the TC, push the bike around with the maximum steering angle and mark off the resulting track. Then measure the diameter of this circle. Most probably a left turn has a different TC than a right turn, depending on what part of the front frame collides first with the middle frame. If so, the average TC is taken.

Front Tubing

Box tubing of 40 x 10 x 1.5 mm is a good choice. It has the same width as the bottom bracket and is narrow enough to fit in the small space between the tire and the chainwheel.
Easier to get is 30 x 10 x 1.5 mm tubing. Initially I doubted its stability, but several pythons use it without complaints so far.

Wheel Size

Front wheel and rear wheel.

CG

The position of the Center of Gravity relative to front and rear wheel, or the steering pivot might be important for the python´s dynamic stability. To determine the CG, place the front wheel on a scale and place the rear wheel on some books to obtain equal height. Then sit on the bike in your riding position and beg another person to read the scale. Then calculate the percentage of weight on the front wheel.


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