A bicycle exhibition in Tampere late in 2007 had several kinds of bicycles on display from past decades. Even though e.g. the wooden bike built by a crofter's nine-year-old son from early 20th century was kind of cool, the most interesting sights there were the recumbent bikes at the very end of the exhibition -- i.e. bikes that you ride in a semi-lying position, feet first. Jürgen Mages on tour with his Python style recumbent. More of his pictures here. After getting home a brief googling took me to two websites, those of Jukka Viirret (Finland) and Jürgen Mages (Germany). It immediately occurred to me that I can build a thing like that, too! Even though Viirret's and Mages' (and also Dirk Bonné's and Esko Meriluoto's) websites were a lot more comprehensive, here's my take on how to build a Python style recumbent bicycle for those who might find that kind of information helpful and/or interesting. I benefited greatly from others' explanations on structure and other tips & tricks, so I hope this website can be of use to someone in the same way. From proto-1 to proto-2 Up to now (3.4.2009) I've built two prototypes, the latter of which has turned out to be rather good, both in terms of rideability and from the viewpoint of further development. What it means is that I'm not planning to build a third prototype. Certain solutions in the 1st proto were used in the 2nd one as well, but overall I find the second much better than the first -- so, to put it bluntly, the first version was merely the inevitable practice I needed in order to build the second. Before being scrapped and cannibalised for parts for the second proto, the first one served about three months for building and riding practice, and on top of that about six months in commuting. What follows is an account of the structural solutions of the second prototype, primarily as pictures with some supporting text, so this is not intended to be an exhaustive handbook for Python construction. But I hope it will be useful when you're confronted by the inevitable quandaries when you're thinking about how to build your own version. Up to February 2009, I've used the second proto for commuting about 25km a day, altogether maybe 4000-4500km. I've skipped cycling during the worst weather conditions (lots of slush, fresh snow and no cycle paths cleared etc.), but a normal cleared cycle path in winter has been just fine. With these reservations I've tried to cycle all year around. Rain gear and lunch go handily into the bags shown in the picture below. Based on the winter riding experiences of 2008-2009, I have to say that I was able to cycle a lot less than I looked forward to, because during winter here on the south-west coast (of Finland) the temperature keeps see-sawing around 0 C much of the time, which means that the daytime slush at +1 degrees freezes during the night, freezing all foot prints and bicycle tyre grooves into an unrideable terrain.. what a pity. Overall I think the guaranteed riding time is eight months a year, from mid-March to mid-November, or something like that. So, above, first the whole thing, before getting down to individual parts, structural solutions and other tricks. The bike is made up of two basic parts, the front and the rear. They are attached to each other only at the steering pivot, plus by an additional shifter wire (in a housing). All in all, the parts can be separated with relative ease from each other. Above, the front. The mud guard is made out of glass fibre and liquid plastic (hartsi), the front tyre being a 47-507 (=24") with a 7-speed Shimano Nexus hub. (The tyre is for winter use.) Above, the rear. The back wheel is a 42-406 (=20"). The mud guard is attached from two points, the one near the fork crown, the other on the rear rack, just behind the reflector. (The tyre is for winter use.) On the left, a close-up on the other half of the steering pivot. On the right, a suspension system of sorts, the same as in Jürgen Mages' bike; the actual suspension is performed by a thick piece of rubber (or in this case, three layers of 1cm thick rubber). At the red arrow you can see the axis, and at the red line, the suspension. On the left, the sketch of the other half of the steering pivot. The actual pivot itself a cartridge bottom bracket, the one end of which is first slid into the slot at the bottom, and then the other pushed into the one at the top. The grey part marks the latch which prevents the upper end of the axis from sliding out. The whole bottom bracket, along with the latch, is tightened with the two bolts that normally are used for tightening the crank arms onto the ends of the axis. Above on the right, a close-up on the lower end of the support mechanism of the seat. Originally the idea was that the seat would be adjustable, but as is evident from a few pictures further below, the way of attaching the rear rack made any real adjustment impossible. The front hub that can be seen on the picture above is thus more a vestige of the original plan than a real, useful function. But it serves it purpose, nevertheless, as the seat has to be supported from the rear anyway. On the left, the upper end of the seat support. From the very top, you can see an arm extending to the rear rack, and on the right you can see how the rear rack is attached onto the frame of the seat, so as to hold it (and the rear mud guard) steady and firm. As was already mentioned, the seat adjustment is not really a possibility -- but it is just about enough to manage the movement that is due to the suspension. That's as good as it gets, though. On the left, the front fork (or loop) with the overall shape visible, made out of 15mm x 35mm cubical pipe, 2mm thick. The loop has been shaped by first welding two rear wheel dropouts onto two 24cm long pieces of pipe. The dropouts with the pieces welded on have then been fastened onto the wheel (or vice versa) so as to start tailoring the loop around the wheel. Originally I used a 26 inch wheel, and the loop became something like the smallest possible to allow the wheel to spin. The wheel itself couldn't be removed and put back on without deflating the tube! This was because the pedals must not escape too far away from the rider, otherwise you'll run out of legs! On the right, the Nexus shifting wire and housing. Above, a way to fasten the flag. The solution for the upper spot shamefully uses black plastic quick strap as a partial solution, so as to prevent the flag escaping too much to the left.. I should muster the energy some time to develop a proper, genuinely tightening tightener, so that I wouldn't have to rely on cheap tricks like this :-) On the left, the whole seat, made out (rather appropriately) of seat belt. The pieces have been looped from both ends, and through the loops you can see a white rope going (if you look carefully), which has been then been tied onto the seat frame. The solution has proved to be rather good. During winter, though, you need a piece of plastic under your arse to protect it from the ultra-cold metal that is the handlebar (not used for steering). The frame has been welded together from whatever pipe I happened to have at hand. The width of the seat is 36cm at the narrowest spot, and 43cm at the widest (both measures are external). In the picture on the right, a detail on the bell and handbrake. The shifter, normally on the right side of the handlebar, is not visible, as it is attached to the front part, which is not in the picture. It's worth mentioning (as it was a surprise even to myself) that even though the distance between the seat and the front wheel might appear very small, it works perfectly, and e.g. the handlebar has not caused any kind of discomfort whatsoever, as the rider's weight (also because of the pedalling direction) is towards the back of the seat. On the left, you can see the manner in which the seat frame has been attached to the handlebar. It is not a fixed joint, but instead two loops welded to the frame go around the handlebar. When the original intention was that the seat is adjustable, naturally a solution like this was necessary. Even now, when adjusting the seat is not really possible, the suspension needs some flexibility. Plus the seat frame can be taken off the bike. Inspection of the picture of the rear part of the steering pivot further above makes it clear that the handlebar, welded onto the back of the read part of the pivot, supports the rear part extremely well. It also turns out (if it wasn't clear already) that the handlebar serves no function whatever for purposes of steering. On the left, the steering pivot, on the right, the lamp. The lamp is a super-cheap LED lamp wrapped into a plastic bag to protect it from water and snow. Above, the ground clearance, 13,5cm. It hasn't caused any problems even while riding in the city (I'm not in the habit of riding in the city, though, anymore than I have to on the way to work.) Naturally some kerbstones are too high for this bike, but most kerbstones have never caused any problems. Necessary further development is hard to come up with, the only evident case that comes to mind is a head rest of some sort, but this far I've managed without. Below, a motley of pictures and other stuff. The pictures above and below were taken during a trip on the Finnish Archipelago Trail in 2009. Above, an earlier incarnation of the second prototype, with a 26 inch front wheel and an orange seat. Notice the front wheel dropouts that are above the loop to decrease ground clearance (it was about the same as it is now with the 24 inch wheel with dropouts below the loop). The weakness of the dropouts above turned out to be that the mud guard must always be removed before you can take the wheel off. When also the tube had to be deflated, this structure caused considerable trouble and strain of nerves when there was always something small you had to do which required taking the wheel off. The final nail in the coffin was when the winter tyre didn't fit properly into the loop and mud guard -- I decided to opt for a smaller front wheel instead. And the 26 incher was the maximum a guy of my height (178cm) could have anyway. Also the mud guard had to be changed, as the solution visible in the picture above didn't protect the rider at all from horizontal sprinkling of water. So as to be able to ride in rainy weather (or on wet ground), I built a semi-closed mudguard out of glass fibre and liquid plastic (hartsi) already before I decided to change the 26-incher to a smaller one. After I changed the wheel, I had to make the new mud guard a bit smaller too, but I didn't need to build a new one. In the old picture, a dynamo operated lamp can be seen. It had to be removed, because I found that a dynamo pointing downwards collects sand and dust underneath the cap, causing friction, and eventually it stopped revolving altogether. As a man of the dynamo camp, I though first of having a dynamo at the rear, but it would have required a long cable from the rear to the front where the lamp would be.. I opted for keeping the front and rear parts as simply separable as possible, and installed a LED lamp. (What a defeat! :-) The orange excessively loud seat material I changed the very minute I got wind of my friend's Volvo being scrapped soon. Salvaging the seat belts I gave them a new live in some serious HPV activity. Above, a sketch by Jürgen Mages on the essential measurements of the Python. On Mages' website you can find a summary of around 20 different Python projects from all over the world. Here are the measurements for my own bike: - Wheelbase 105cm - Ground clearance 13,5cm - Steering pivot angle 70dg - Trail -33cm - Bottom bracket distance to front wheel axis 36,5cm - Bottom bracket distance to the edge of seat 72cm - The difference in the height of the bottom bracket and seat 11cm - Seat height 32cm - Weight 20kg (without bags) - Weight balance (bike + rider = 90kg): 56% front,  44% rear. - Distance travelled: 10.376km (24.8.11) Here's how it all started in December 2007: the first prototype. Links to useful websites: - Jürgen Mages (the "inventor" of Python style recumbent) - Dirk Bonné - Fleettrikes.com - Python Wiki - Esko Meriluoto (in Finnish and English) - Jukka Viirret (in Finnish)