I found out they have great Q&A videos on their YouTube channel. They answer here why golf ball dimples are unnecessary for a fin-like shape. https://www.youtube.com/watch?v=ZXpZy_A7mMk

Golfball-like dimples are only half my question. In aircraft much work has been done on reducing boundary layer issues with suction holes that actively remove turbulent air. Some aircraft engines, the SR-71's in particular, do this to ensure 'clean' intake air.

Subsonic: http://www.dtic.mil/dtic/tr/fulltext/u2/274329.pdf

Supersonic: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2006002...

Speaking of the SR-71, you guys should all read the heavily reposted stories about it. It's such an amazing plane. While it's not flying in the sky anymore, it deserves to fly in our imagination every time somebody speaks about it.

http://oppositelock.kinja.com/favorite-sr-71-story-107912704...

The majority of the drag affecting a modern HPV racer is caused by the wheel aperture. Perfectly fitting the fairing to the tyre isn't practical, due to flex in the wheel and the tyre casing. Managing airflow around this gap is a largely unsolved problem.

Some improvements could be made by reducing the rolling resistance of the tyres or the efficiency of the drivetrain, but this will have only a relatively small impact; this drag increases linearly with speed, whereas aerodynamic drag increases geometrically.

this is very interesting. What if the vehicle flew in ground effect (small retractable wheels for takeoff)? You'd also need a propeller for propulsion. You'd drive off the road easily though.

Dimples on golf balls help in inducing turbulence, not the other way. Turbulence in this case reduces drag significantly. This is a well known counter intuitive result in flu mech.

Weight, air flow for rider, friction, even more arodynamic profile, ergonomics, better fit for rider. I suspect a better bike might get you 10% more speed, but each 1% is going to keep getting exponentially harder.

Maybe the road surface? I'm assuming an actual highway has some friction that could be sacrificed perhaps? Not sure what the cutoff is there before too little traction becomes problematic?

Just spitballing here, I have no idea how most of this stuff works.

Related to road surface, are properties of the tires used. The goal is to optimize for rolling resistance. On a long brevet, different tires can shave hours off your time.

Since their requirements for durability are much lower (i.e. they don't need to get days or months of use), they could optimize for tires that are just durable enough for the event and have minimal rolling resistance.

Suspension losses are another area where power is lost. I'm curious if it is possible to perform these tests in a velodrome where gains from better tires suspension would be minimal.

Also check out motor-paced records, where the current record is 166.9mph by Fred Rompelberg.

https://en.wikipedia.org/wiki/Cycling_records#History_of_mot...

http://mammajammaride.org/wp-content/uploads/2014/08/Fred.jp... http://fredrompelberg.com/upload/images/site/Wereldrecord_fi...

This is worth a read on the surface of the Bonneville salt flats: http://saltflats.com/traction.html

Does it have to be a bike? What about a rowing rig, where you can leverage the powerful muscles in your back and upper body?

Contrary to what it might look like, rowing is almost entirely dependent on your legs, your arms/back merely keep the momentum going at the back of the stroke. Also, the muscles in your back are nowhere near as strong/large as the muscles in your legs, there's nearly a magnitude of difference. Though if you added power from your arms in addition to fully utilizing your legs (it would be much harder to concentrate) then there would be a benefit. But then you run into how to engineer such a thing, especially with respect to aerodynamics.

The limit is cardiovascular, not muscular. World class rowers and cyclists have about the same power output. A rowing bike would be larger (so less aerodynamic) and difficult to engineer.