Stupid Mistakes #2

I did it! I bought the kid bikes from which I will harvest the front forks. Walmart kid bikes are much cheaper than buying the parts from even online bike shops, and who knows? I could even put the rear section together with the front wheel from the mountain bike and make a delta trike later.

I got what I paid for, which is Chinese crap. The steering and the axle turn like in place of ball bearings, they have twenty-sided dice. If you apply a little force, they go bump-bump-bump, about 3-4 bumps to go through an eighth of an arc. Swell.

More Steering

Now what I need to decide is how to mount the steering mechanism. Options:

1. The easy way, relatively speaking, is to cut out the steering system from the old bike and affix it under the seat. Unfortunately, the old bike's head is longer than the space where it needs to go, so this is out.
2. I could cut off the top of the old bike's head. This would allow me a solid steel cylinder to put the yoke into, and a system of bearings to make it turn easily. I would need to devise my own way to keep the yoke from pulling up out of the head, and I would lose some of the anti-wobble effect of the longer head. Not sure the impact of losing the bottom system of bearings, beyond these two. Also, the yoke is too long for the space, and would also have to be shortened.
3. A variation of # 2: I could cut out the middle of the head, and attach top and bottom together. Would give me the bottom bearings, but would make the head a weak-point. All I could do to join them would be to apply epoxy, and this might also compromise the free turn of the handlebars.
4. Find a smaller head. The main problem here is the hassle and cost.
5. I could attach the handlebars to a perpendicular pole, then put a simple pin through the pole, and be done with it. Say, use a short bolt, one of those quarter-inch ones that has a length without threads. There'd be more wobble than either of the above, and it wouldn't have the bearings to turn so nicely around, so precision, high-performance steering is out. But it's by far the simplest.

Steering

There are two basic formats for steering that I can think of, illustrated in the diagram above. The green bar is the handlebar, the blue dots are joints, the red are steering bars. The triangle represents the stem of the yoke that turns the wheels, in black. The handlebar turns about its center, not marked.

The first thing I think about them is that the push-pull format seems to work best when the steering is significantly behind the wheels, although I have seen other designs that use the lateral design from behind, and use a bent bar (the long red one in my diagram) to reach the wheels.

I think the real difference is the travel, how far you turn the handles to turn the wheels. I think the push-pull method would make the wheels turn quickly with very little motion of the handlebar, not a good thing. In the lateral method, the shorter the little bar (red) that connects the handlebar with the long red bar, the longer the travel of the handlebars.

It's also the method I've seen on pro trikes.

Steering mechanism

Another decision was how to rig the steering when your technical skills are limited. Most Tadpole Trikes (two front wheels) use a design where the crossbar of the frame heads out toward the axle, then has a hinge. This is clearly the superior design, but I don't know how to find such a hing. I don't think door hinges will work. So my thought was to take the front end of a pair of kid's bikes, and have the crossbar connect to the cylinder.

• Use a bike with a small front tire, say 16", so your bike doesn't look like this:

The downside is this involves a bamboo-metal connection, but we'll deal with that in a bit.