Very nice! Using 8020 for the cross bars is an interesting idea. It might be slightly heavier than a 1x2 tube, but it would be much faster to fabricate than the tube and bracket method we use (from the team 221 superlight chassis). It eliminates 2 fabricated parts and allows the use of 1/4-20 hardware rather than #10 hardware at the corners.
I also like the vex bearing plates for the outer wheels. Another nice fabrication time saver. It's funny, we were just discussing this idea at the FRC summit at ODU on Saturday. One question, does the use of the vex bearing plates allow the chains to be moved inside the side rails?
To spark some ideas, check out the video of the
presentation I gave on the evolution of the Triple Helix west coast style drive trains. Any chance you will have your drive train at the FRC workshops in Richmond?