What is unique about these two bikes that makes them drastically faster than every other (very) similar bike on the market?

This whole subject of bicycle aerodynamics really depends mainly on if the bike has to meet any sanctioning rules, or if [none], then how normal you want the bike to look. A $100 Wal-Mart bike with a $100 home-made fairing and body sock could easily be 10% - 15% faster than any of these high-end "pro" models from the big companies.

You have to go to recumbent-bike-land to learn these things tho because for the most part, mainstream bicycle racing has been sticking their heads in the sand for a number of decades now.


And speaking of Graeme Obree--his Battle Mountain bike was also prone... -And used linear/treadle pedaling.
Which is two ideas tried many times in IHPVA events in years past, that haven't ever been found to work well.
(Also his was a fixie besides...? for a 4.2 mile TT,,, IIRC)

A couple of the Battle Mountain old-timers emailed him and gently tried to tell him that is bike design was very much not ideal, and they were willing discuss the matter with him privately or he could just look around in the archives at recumbents.com that showed pictures of the last few years' better entries. He declined all that and continued on his own way, which wasn't too surprising in itself--but I suspect that he thought he was doing something new, and he wasn't. He was doing something old and pretty much discarded, by many other people who do this as a regular thing.

A lot of people hoped he'd return with a better bike, borrowed, built or bought--to show what he could really do. After his one rather lukewarm attempt he seems to have lost interest, it appears.