In the spring of 2001 me and a friend (Michael Nahl) both built a flevo racer type recumbent. His is on the basis of 26inch wheels, mine has the smaller type wheels: 20inch (406). The original idea was that by changing some settings on the bike you could convert it between the two types. Although this sounded great at the time, it turned out to be pretty useless: I ride small wheels and he does the large ones all the time.
Yes, it is, and I use it for commuting (20km, one way). It has front wheel drive, 24 gears and uses the moving bracket to steering: you steer with the feet. Once you get the hang of this (you need lots of patience) it's a real nice way of moving about: you have your hands free, and have a real cruise feeling ---may be because steering, pedalling is all done subconsciously.
Because there is no chain running from end-to-end the bike can be split into two pieces (using one screw) and be transported by train (as "hand" luggage) or put in the back of a car.
I live in a very hilly area, where there are a few steep climbs (going to 15%). Although not ideal, this bike does climb them. When we built the bike we tried to put the seat as much in front as possible, and use a largish wheelbase. A question of putting the point of gravity to the front. I measured it and it is at two thirds of the wheelbase... Still, when the road is in a bad condition or simply wet you need to be careful with a slipping front wheel. Also, the bike tends to be instable at the particular steep hils, caused by the steering angle of 45degrees and the weight of the front part including the weight of your legs (compare to 75degrees normal bikes have). The low steering angle makes the front part to drop away. This can be mastered by technique: most climbs except for the really steep ones I can do hands free now.
|gears||11-32 and 60-33|
|steering angle||about 45 degrees|
Building a bike isn't as difficult as it may seem. You need a minimal set of tools and lot's of time. This is especially true if you do not have much practical experience in metal working (e.g. you are a programmer like me). You need a set of files, a saw, flex, brazing equipment and a marking gauge. Be careful: you can buy yourself poor on equipment, but actually in most cases you can help yourself with the file. We did have access to a mounted drill (what's the word for "standboormachine"?) and that was a relief.
The tubing we used is square 35x35x1.5 and 30x10x1.5 construction steel. It is easy to get and real cheap. It is also way too fat. We could have made the bike lighter (its 18kg all included). A square tube is easy to work with but has less nice properties concerning stability then tubing with a round cross section.
Most of the joints on the bike are brazed. Sometimes using silver (30%), sometimes brass. We learned brazing while working on the bike, and it is easy. In a nutshell: you clean the parts from rust and dirt, put flux on it, heat the pieces and when it is hot enough you apply the silver or brass. I did buy a practical oriented book to have some background material. The book is alright and gives you many tips. Note, brazing holds best using sheer forces, but it need a contact area for that. That is (one reason) why lugs are used in bicycle construction. Using capillarity effect the brass/silver penetrates deeply between the lug and the tube. When doing a lugless construction as is the case here, you do not have a lot of contact area. This can be circumvented by building up big fillets at the joints. This technique is called fillet brazing. When doing fillet brazing you need to use brass or rods with low silver content. High silver content rods are too fluid.
For good brazed joints you will want to minimize the gap. Which means that you will need to be precise. These things are best done by bying some expensive machines, but instead I used templates out of paper which I wrapped and glued around the tube. That way I could quickly file the edges without having to try out or measure for a fit. The templates were generated with a perl program. I made it for myself and therefore isn't very comfty, so you will need some perl knowledge to adapt and use it. Moreover, it is not generic, it can't calculate the section of any two tubes crossing (it knows how to do round and rounded rectangle tubes). The output is postscript format. The following picture is a example of such a template. It depicts the section of the front piece with the steering tube. The vertical lines ease the alignment of the paper onto the square pipe.
Square tubing has a disadvantage for brazing. At a joint between two square tubes you have only two sides to put your brazing fillet. The other two sides only hold using a tiny bit of brass. I once fell sideways and hit the seat real hard, causing such contact face to crack. You can see the rip in the first picture above. It has been like this for many months now (to lazy to repair it), it doesn't get any worse anyway. The solution is to braze a sheet of metal (1mm thick, 1cm height) over that joint. This way the brass would hold the two tubes through shear force, and that is where brazing method is best at. I used a simular technique on other parts of the bike and they haven't shown any problems yet.
The rear part of the bike is too long. Instead we should have made the middle part longer. It would have made the bike lighter, but more importantly, it would have made it stiffer too. At the moment the tension of the screw connecting the rear with the middle part is very critical. Any tolerance on that screw is amplified to the rear wheel. The same thing problem caused by the elastisity of the rear fork itself.
I tried to ride some time with the handlebars horizontally. But I didn't like that very much: it feels like I am steering a wheel barrow. And I've read that this handle bar position is potentially dangerous in accidents, because you do not have something to stem yourself against. So I turned them around to point upwards. Which I feel is perfect for me. But another problem crops up: it's raining into the brake cables. This can be particullary fun when it starts to freeze... I have no satisfying solution yet. I though of making a waterhole in the cable and using inox wire as cable. Or filling the cable with grease. Or putting something over the brake levers so the water cannot enter.
I mounted the bracket (BB) the wrong way around. Normally the cartridge is screwed in from the right, here it needs to be screwed in from the left. I thought it wouldn't matter or even would be better, because the thread is left handed. But I was wrong. The cartridge kept unscrewing itself. I solved the problem using locktite onto the thread to fix it. This ain't elegant, and I can't get it of without heating and thus destroying the paint on that part.
On the way to work I to go through forest and drive on country roads. In winter snow isn't bulldozed off the road and the salt is only thrown in symbolic amounts (making things worse). My flevo was unridable in these conditions. I had the feeling that the steering principle made it much more difficult than any normal recumbent.
To solve the problem we made a three-wheeler out of it. Because the rear part cannot take the torsional forces that would be caused by a fixed rear bridge, it is necessary to put a axle in between. I used a the head tube of an old bicycle. Cut of the fork and fixed the crown to the bridge. Although slightly complicating things, it had added benefits: center of gravity is better in curves, you aren't bothered by roads dropping sideways, you feel the pottholes only half (we have a lot of them in East-Belgium).
Dunno. I am quite satisfied with the one I built now, but I do think about making a new one. It's probably going to be front wheel drive again, but I am going to be sitting lower so weightshifting when climbing is less. And it is going to be lighter. And folding should be easier.
This bike is called the "pedaaltroon" (pedal throne). I got the name from a dream I had lately. In that dream my bike was being admired by some kids. And one of them cried out: "oh, so you're riding a pedal throne!". In the real world a lot of people (not only kids) react positive when they see this bicycle. It strokes my vanity, so may be it sometimes does feel like a pedal-king.