The reason is because if you are greatly concerned about aerodynamic drag, you can get a recumbent that has way less frontal area than an upright bike. No fairing can really make up for the upright bike's larger frontal area, and the tall profile makes them susceptible to crosswinds in regular use.

Last time I looked--Zzipper and Windwrap both make small fairings that you can mount on the handlebars of an upright bike, if you wanted.

The info from Bicycling Science may be technically correct but it seems rather outdated.
The Vector trikes and Avatar Bluebell bikes date from the mid-1980's; they look pretty slick but both of them are roughly 30 years old. I don't know what their drag numbers are but I'm pretty sure that they would both be totally uncompetitive today.
The Varna Diablo was probably the fastest direct-sight recumbent bike, before the camera bikes took over.

In years past there were Battle Mountain teams that ran faired upright bicycles.
There was also one team that showed up a few times with a fully-faired folding bicycle.
Neither of them went anywhere as fast as the faired recumbents did, but they still went way faster than an unfaired bike of the same type could.

You might ask on the recumbents.com website if anyone has more info on either of these. That site is fairly small but does seem to have a lot of IHPVA/Battle Mountain regular attendees.

I guess now there's also this.

I have flipped over the handlebars exactly zero times so I don't know if this would be better than a recumbent for aerodynamic touring.

One of the local news reporters did a segment on that bike. He was able to ride it although rather slowly and awkwardly. The inventor claimed the problems were due to a bad fit. The inventor appeared to have much better control and claimed speeds of up to 35mph were possible. No mention was made of grade to hit the 35mph.

The Bird Of Prey bike isn't new, there's news reports of it going back at least 2 or 3 years that I recall.

A lot of people have tried building prone bikes like this, and riding comfort usually ends up being the major stumbling block. In particular--you end up needing a head rest, because your neck muscles get tired extremely fast holding your head up in such a position. You might supposed that you could build your neck muscles up to it, but that is very very difficult to do. This is why many riders get Shermer's Neck on ultra-long riding events like RAAM, despite lots of preventative training for it.
https://www.bikeforums.net/road-cycli...er-s-neck.html

If you want good long-distance riding comfort, you're much better getting a regular recumbent than that thing. Or *any* prone bike, it seems.

Speeds of up to 35mph are possible on a Specialized Tarmac.

And on a BMC TM01 over long distances

Ergonomically, it's a disaster. Prones have come and gone over the years, and then come and gone again and again. They tend to be useful in sprints, but not much else. Nobody can 'stand' the position for long enough. Maybe having a cool name, like "Bird-of-Prey" will help, though?

Not really

I would think whatever the Bird of Prey can do a NoCom can do better.

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.

There's nothing unique about the Tarmac. It's a great race bike, best handling bike I have ever ridden, but it isn't even Specialized's aero bike. It was an admittedly snarky comment on how 35mph isn't remarkable. Even for a 49-year old Cat 3. 35mph isn't going to win you many 45+123 crits, at least not around here.

LOL I'd like to think so, anyway.

Edit: added pic when I finally found it. Upright on tops, hoods, drops, aerobars, followed by highracer (in a relatively conservative position,) followed by a NoCom. They're all sized correctly based on the front axle height, although the NoCom pic was taken from too close and the perspective makes his feet look too big and his head look too small.

Seems like you can't flip over the handlebars because your groin will smash into the seat area instead?

I think when you take into consideration practicality and comfort recumbents win for aerodynamics. Otherwise you need to get into fairings and velomobiles which gets expensive and sometimes silly. But then you still need the upright for hilly terrain or rough terrain .

The moral is that there's not a single ideal engineering solution for human powered wheeled locomotion.

They are more adaptable than most people give them credit for.

I use recumbents for gravel roads, fire roads, and double track. Anything more technical than that requires something more capable than what I have. Examples:

https://rothrockcyrcle.wordpress.com...ack-on-gravel/
https://rothrockcyrcle.wordpress.com...wn-laurel-run/
https://rothrockcyrcle.wordpress.com...greens-valley/
https://rothrockcyrcle.wordpress.com...r-o-overlooks/

And I use them on mountainous brevets and permanents (upwards of 80 to 100 feet of climbing per mile). Some are mixed surface. Examples:

https://rothrockcyrcle.wordpress.com...nishment-200k/
https://rothrockcyrcle.wordpress.com...e-gates-goofy/
https://www.bentrideronline.com/messa...ad.php?t=74264