Sketches with Dimensions

I initially sketched these in my notebook and have just thrown them into TurboCAD and exported them as gif's to get the size down. So none of the angles is really right, and a lot of the bits are just put in by eye. But the dimensions are real, so they are more or less to scale. TurboCAD does 3D after a fashion (no cylinders in the cheap version) and it works reasonably well. And it's $US100. The first sketches took a while, it's been a long time since I used a CAD package and this one lacks some of the features I'm used to from AutoCad R13... so this is all pure 2D.

First, the Greenspeed. This has about a 40° seat angle.

The TriSled with a roughly 30° seat. It really is a pretty curvy seat, so the angle I measured is basically the hip to shoulder one.

My Kotzur recumbent bike, again about a 45° seat. Wheelbase about 1.1m.

Having got at least a vague idea of how big the bits of my other hpv's were I decided to start making a list of their other features.

This is the first attempt at a trike for me, just showing how I can demount bits and make the seats slide. I'm also looking at sizing and seat angles. So this first sketch is just the Greenspeed design with the addition of removable bits.

The TriSled uses roughly 1.6m from the far pedal extent to the back of the headrest, and that is (I think) about a 30° seat. So going off that and a 0.8m rear rack I will need a minimum of 2x1.6m+0.8m = 4m long. The GS is a shade over 3m, and that's long.

Given the nature of CAD, it's easy to come up with wildly- overprecise designs, so I printed this then pretty much ignored it. Well, I cut to more or less these sizes then tried to build something that looks a bit like the picture.