I finally completed the new handlebar setup for my M1. The previous setup worked fine, but using a conventional V-shaped handlebar resulted in the brake levers facing the wrong direction, causing almost the entire surface area of my XL hands to be facing directly into the air stream. The picture below also shows how cluttered it looked. On a bent designed solely for speed, this was far from ideal, so some radical redesign had to be done.
This was the design I came up with to replace it:
The horizontal crossbar is just a piece of 7/8" aluminum tubing, sourced from a hardware store, while the grips on the ends are made from a set of Bontrager mountain bike grips with the curved ends cut off. The Di2 TT style shifter pod has an expander plug on the end which fit perfectly into the aluminum tube.
When I removed the existing handlebars, I noticed that the manufacturer of the tiller had done me the favor of drilling a large hole in the base of the handlebar clamp. This gave me the idea of routing the electrical wire from the shifter pod internally through the crossbar and down the length of the tiller, where it exits through a slot and plugs into the Di2 junction box. Very clean and aero. Eventually I'll want to wrap some bar tape over the grips, but I need to do a few test runs first in case any further tweaking is required.
After some experimentation, I angled the brakes outward slightly so that the levers would fit into the web of my hands for best leverage and comfort. This also made it possible for my thumb to press the shifter buttons without interference from the lever, so that I could operate the brake while shifting gears if need be. On the left side I installed a bar end mirror which had been in my parts bin for years. Positioning it as shown behind my left hand keeps it out of the airstream. As before, the width of the grips positions my hands directly behind my thighs when pedaling, thereby hiding them from the wind as much as possible. On the trainer, everything worked flawlessly. Shifting up and down through the gears is effortless, and the Cane Creek brakes seem to work quite a bit better than the ones they replaced. All that remains now is to take it for a test ride.