Bike project 1: Design continues

I've continued to work on the design.  After some false starts I've done a redesign based on the Robinson 2x4 design.  I bought the plans a few weeks ago and decided to derive off of the 26" design.  There are a couple of errors in his measurements but some work with sketchup sorted those out and I've now got a reasonable next cut at the design.

Here you can see the Robinson design in the background.  Notwithstanding Robinson's notes the actual wheelbase is around 52" not 48". This moves the front fork assembly forward and reduces the angle from the rear axle to the base of the headset improving the overall design.  I've also adopted his seat profile.  In this design iteration I've moved it back 6" or so and lowered it to make mounting and stopping easier.  I'm still experimenting with frame profiles but the general idea is shown here.