Dunno, really, Deeg! But we engineers are great at educated guessing, so here goes:

Top riders can generate over a thousand watts (1.3 horsepower) for short duration, and Floyd I think did around 450-500 on his great climb last TdF. Horses as a standard assumption produce on the average one horsepower, around 750 watts. I'd assume race horses are at least twice as good, and by analogy could generate peak power in excess of two thousand watts.

So a Floydish rider has a peak power around 1.3 hp and a race horse around 3.2 hp. The race horse weighs perhaps 1000 pounds and Floydish with bike perhaps 200, a 5 to one ratio. Floydish would have a power to weight ratio of 154 pounds per horsepower, and the race horse around 300 pounds per horsepower.

It's surprising to me that a Landis has a definite possibility of outrunning a race horse on his bike!

I don't say he CAN outrun the horse because of the general looseness of my analysis.

Road Fan