From the blurb I wrote for the university press release:
“Mechanical and aerospace engineering graduate students Nick Badger and Andrew Smith competed in the Parker Hannifin Corporation’s 2012 ‘Chainless Challenge,’ in which students designed and built a human-hydraulic hybrid bicycle. The competition was held April 12-13 in Irvine, Calif.
Instead of a direct chain link from the pedals to the wheel, the rider pumps and pressurizes hydraulic fluid to power the bike. Badger and Smith’s recumbent design, complete with a hydraulic infinitely variable transmission, won the Ingenuity and Novelty award at the competition.”
As it turns out, we had a shaft coupling come loose during shipping, and we couldn’t actually compete in the race. But we still had a very strong showing, and the fact that we didn’t come home empty-handed is a testament to that. The most frustrating part for me, especially because I was responsible for the entire mechanical design of the bike, was that I learned years ago (from the microturbine project, actually) that, especially when working with small assemblies, shaft couplings will make or break you. Unfortunately, with only two of us to manufacture such an ambitious design, we were simply just too pressed for time to do the couplings the right way ourselves, and our budget was too small to get the gears splined. With the wall thicknesses so thin, that definitely would have been my chosen coupling method.