> John H.: Maybe PhysicsMan can settle this
> with facts? Come on PM, break out the
> slide rule!
> dchan: I can't remember the formula
> (Physics man?) but I seem to remember that
> the wind resistance goes up exponentially
> with speed depending on surface area.
Hey Guys - In the past week or two, I've been busy and not as active on the skiing forums as I would like to have been.
Anyway, I looked over the previous posts in this thread, and if I think the question is essentially whether a bicyclist going down the same grade as a skier would go faster or slower.
Its kind of a vague question because to make it specific you got to specify all sorts of things that you can't really specify
but what the heck - here goes.
First, I'm going to assume that the bicyclist is on a nice paved, smooth surface of whatever grade is necessary for the test. I realize that it might be a tad difficult to locate a nice smooth road with a 35 degree slope (and get somebody on a bicycle to go down it and reach terminal velocity).
There are two classes of forces which impact both the hypothetical skier and cyclist: aerodynamic drag and "everything else".
Aerodynamic drag is proportional to Cd (drag corfficient) TIMES the velocity squared. The coefficient of drag depends fairly weakly on velocity and a bunch of other things.
The "everything else" category includes rolling resistance, bearing friction, Coulombic snow friction, (snow) plowing and compaction drag, etc. The net effect of all of these forces can be approximated by a constant plus a second constant times velocity (to the first power, not squared). As usual, see, "The Physics of Skiing" for a more complete discussion of these forces.
On really low angle slopes, you never are going all that fast (on either a bicycle or skis), so you can neglect aerodynamic drag for both the biker and the skier. Since the various non-aero drag forces acting on the bicycle are less than those acting on a ski, the bicyclist would clearly win. In fact, if its a low enough angle hill, the skier might not even be able to overcome static friction and hence might never even get going - grin.
OTOH, consider what happens when you are going fast on really steep slopes. Since the worst of the non-aero drag forces increases only linearly with velocity, whereas the aero forces increase as the square of the velocity, the aero drag forces will always dominate the non-aero drag forces, and the answer pretty much comes down to the single issue of which is larger, the Cd for skier or the Cd for the bicyclist.
My guess is that unless you are allowing something like a low recumbant bicycle with full aero fairings, the skier will almost certainly win. The Cd of normal cyclists is almost certainly much larger than the Cd of a skier in a full tuck.
Just my $0.02,
Tom / PM