Saturday, 08 May, 2004

Laws of Physics and Cycling / Armadillo Hill Country Classic

There are two widely unknown laws of physics you should know if you're considering taking up cycling.  These laws are well known to cyclists, but the general public is not aware of them and physicists for some reason do not publicize them.

The Laws of Physics and Cycling

  1. Headwinds are stronger than tailwinds.  If you've ever ridden in wind you know this to be true.  If you head into the wind at the beginning of your ride, when you turn around to head back the wind will slow.  Similarly, if you head out with the wind, when you turn into the wind it increases.  This also is true of circular courses, where a wind coming from anywhere on your front will be stronger than any wind that quarters from behind.  Headwinds increase as the ride progresses.  Tailwinds diminish.  The average ratio of headwind to tailwind is approximately (I don't have the space here to show the proof) 2:1, but it never approaches 1:1.
  2. Hills are larger, steeper, and longer on the way up than on the way down.  Pedaling up a hill will lower your average speed more than pedaling down the same hill.   It often is impossible to measure the effect that going down a hill has on your speed, but regardless of the hill's steepness you can always measure the effect that pedaling up has.  Physicists are still trying to determine the exact relationship.  There are many variables, including the smoothness of the road and the hill's position relative to your starting point.

I took part in the Armadillo Hill Country Classic today--a 100 mile ride organized by the Austin Cycling Association.  Today is the first time I've done this ride.  It was well organized and well supported.  It was a good course except for the many hills and the headwind on the return.  Even so, I managed to turn in my best time ever for a 100 mile ride.  I didn't do everything right.  I slacked off on the eating and drinking about halfway through and bonked badly at about 70 miles.  Fortunately I recognized the problem before it got too bad and began increasing my consumption.  10 miles of taking it relatively easy and I had my strength back.  This is a very good ride that I would recommend to anybody.  They had six different distances from 14 to 120 miles.  Well worth checking out ifyou're a cyclist in the Austin area.