Notes on frame parts

None of the bicycles I have currently have the correct dimensions for using the triangular front-end as-is on the back of the Bike With 2 Brains, so I'll have to custom build those parts. It's probably for the best anyway since I don't like the size of any of the top brackets.


Redesign frame

I redesigned the frame with a rounded top and moved the rear wheels as wide as the edges of the seat. Prior to deciding to make the top frame rounded (which is an aesthetic choice) I had to make the eyes (in full scale) to test that I could indeed bend Schedule-style steel pipe with the hydraulic bender I have.

I moved the rear wheels further apart for aesthetic and practical reasons. Aesthetically, the copper model looks like forward is indeed forward owing to traditional conventions of wider wheelbases in the rear of vehicles. Practically, 24-inch diameter wheels would hit one another if the axis of rotation was only 24 inches apart.

I think it's a good decision because it'll improve stability as well — the only downfall is that it's not so clear how I want to make the whole frame come apart so I can transport it.

Second copper wire model


Create full-scale eyes to test pipe bender

Dimension drawing of eyes

Full-scale steel pipe eyes

I decided to build the eyes first. I have some pieces of Schedule-type steel pipe which I wanted to make sure the pipe bender I have can actually bend it — and in a controllable way. I also tested to see if I would have to strip the pipe to bare metal but it appears I can just use a wire brush to knock off the loose zinc and rust for the paint to stick.


Frame disassembly brainstorm; unicycle lament

I decided I can use 3/4" pipe unions (which are three-piece deals; two of which have threaded ends and the third is a nut that keeps the two other parts together. They are beefier than typical pipe so they should be strong enough. Unfortunately, they're about $3.50 each so I'd like to see if I can find them as they are removed from old construction.

I also noted that even on eBay, the base price for a unicycle is $75 with shipping. has the "cheapest" unicycles which sell for $63 with $12 shipping. On eBay the situation is worse with sellers using exorbitant shipping costs to offset low prices. So far, $75 is pretty much it.


Original frame design and first copper wire model

The bulk of the frame is a pair of direct-drive bicycles placed two-feet apart. Triangular parts maintain structural integrity and an overarching roof structure provides support for the windmill generator and to resist bending from the rigors of pedaling.

All four wheels are 24-inches in diameter and the rear wheels caster to allow the front wheels to provide steering as well as propulsion.

The frame has been modeled in 1:15 scale using copper wire. The material and scale were chosen because they were convenient. Although balsa wood and glue would also have worked, 14-gauge copper wire and solder were more readily available. The scale was chosen by printing the CAD drawings on an 8 1/2" by 11" page and then cutting the wire according to the lines on the page.

First copper wire model