The Trike

I built a thing. To be specific, I built a recumbent tandem tadpole tricycle, but I’m just going to call it a trike because that’s easier. Here it is:

It has a number of interesting features.
For one, it can be steered from the back seat. Which is also where the shifting and rear brake controls are. I designed it intending to captain in the rear myself, to afford my ‘stoker’ the better view. Those are tandem jargon, usually corresponding to the front and rear positions on a 2-person bicycle, but in this case the positions are reversed. Captain sits in the back, in other words. The front seat also controls the front wheel brakes, and can steer. This is the steering linkage:

It also uses biopace gears, as shown here:

I have a general preference for biopace gears, especially because of how I pedal and due to an old knee injury. All of my bicycles are fitted with them. I find the transition between reciprocal motion of the leg to rotary motion of the crank to be smoother, especially at higher cadence where I try to spend my time. I spin between 90 and 110 rpm, usually, a speed most enter only when sprinting. But here’s the thing about spinning vs mashing(the other way to pedal). If you’re spinning, you’re further from the physical limit of force you can put out onto the pedal. With mashing, you’re going to be at like 80-90% of your max force all the time so when you want to go faster, you can only give it the remaining 10% of your effort. (aside: For the purpose of this brief comparison, there is no 110% effort. 100% is the most you can do. period.) And if you want to go really fast, you are going to end up spinning anyway, because there are limits to how much development you can get without severely impacting your ability to ride at low speeds and get going. (another aside: Development is a term for how much the rear wheel moves per turn of the front pedals. More development=higher speed) I’ve seen very large front gears on land speed record vehicles, but those needed an assist to get going. Normal bicycles have some limits on the front gear. The rear can only get so small before it is inside the axle. So limited on development, eventually if you want to go faster, you end up in your highest gear having to pedal faster to go faster, so you end up spinning anyway. I spin at or near those kinds of cadences all the time, just in a lower gear, so the force i’m putting on the pedal in each stroke is minimal. This is also better for my bad knee. Less force => less stress on the joints. And with biopace, the faster cadence doesn’t cause trouble either. I’ve pedaled at up to 150 rpm before without any lasting pain. And when I want to go faster, I just shift into a higher gear. Usually I’ll spin up past the top end of my normal cadence first, so I don’t end up mashing too hard to get up to speed in the new higher gear. I rarely, if ever, end up in my highest gear. This has been a fairly poor description of the two ways of pedaling a bicycle, and I’m sure there are more ways to pedal and strategies for shifting, but this is mine.
Back to the trike, it uses a fairly rare 24” wheel and a mountain bike cassette(since it was nominally built from a mountain bike). These combined give it ample low-end torque. Which is good because it weighs a lot. Takes much effort to get it going from a stop.

It uses V-belt pulleys, not proper idlers for chain management. These were cheaper. I’ve used them for years on my other recumbent.

Here are some more images:

A combination of its excessive weight and the lack of strength from my cycling partner means that the trike does not get used at all, unfortunately. It is also too big to fit on most of the trails around here. I made the front track too wide. But it had to be wide to fit around shannon(she is a wide girl). At the time of its initial design and construction, the trail closest to our house was wide and did not include any crosswalks. It would fit on said trail. But the trail near where we live now is not so wide in parts. It also includes crosswalks which involve very tight turns. The trike can be ridden on the streets, no argument about that. But I’m still probably going to get rid of it. It was not so much money sunk into the project, and it was a successful project. The only way I could improve it would be to rebuild the frame out of aluminium. And even then it would still be a heavy bike.