I finally have a chance to sit down and cover the last few months of updates. After blowing the second sprag sprocket design, I made a new one using a sprocket made of hardened tool steel, with a pressed-on ring to reinforce it.
This design still had a major flaw. The ratchet pawl had a habit of flattening out and mushrooming at the tip, which would prevent it from seating and cause it to break and lock the ratchet. I solved that by filing large chamfers on the sides of the contact edge, and oil hardening the parts, but this still needed to be rebuilt every 20-30 miles or so. This was good enough for racing, but I wanted to eventually use the bike on the road.
The final design uses four ball bearings that sit in ramps on the inner collar that is locked to the shaft. The sprocket has a series of shallow notches machined into its inner surface, and when it spins in the direction of the ramps, the balls roll into the notches and lock the parts together. So far, this design has lasted for over 100 miles without fault.
The last major change I made was to replace the ANSI Type 40 roller chain with SAE Type 420 O-ring chain. This is compatible with ANSI 41 sprockets, so I remachined the sprockets to the correct width. The regular chain was throwing off the grease too quickly and then seizing links, and O-ring chain will last longer.
I've also completed a full set of blueprints, the associated documentation, and a full costed out parts-list for this transmission design. If anyone is interested in making a copy of this design, or having parts manufactured by me for their project, you can PM me at John.W.Petsche@gmail.com