[net.bicycle] WORLD RECORDS at the US OLYMPIC TRACK TRIALS: reduced drag at altitude

neal@druxv.UUCP (Neal D. McBurnett) (07/11/84)

Thanks for the update, Bruce.  One point, though: as I understand it,
the drag at 6000' is about 80% of sea level, not 50%.  It is directly
related to air density, and as I recall, the density at sea level
is around 1.2 kg/m**3, vs a little less than 1 kg/m**3 at 6000'.  Still
quite an advantage, though!  Since the international records-keeping bodies
do not yet take altitude into account, I've heard that one of
the best places to set a long-distance road race time is in the San Luis
valley of Colorado.  Rt 17 is straight and level for 40 miles north of
Alamosa, at nearly 8000' elevation.  Offhand I don't know the air density
at that elevation, but if we use .9 kg/m**3 as a guess, the drag would be
.75 of the sea-level drag.  Since, at high velocity, speed is roughly
proportional to the CUBE-root of power supplied, if we assume constant power,
someone could go faster by roughly the cube root of the density ratio,
or about 110% in this example.

Hope I didn't blow anything in this quick analysis...
-Neal McBurnett, ihnp4!druny!neal, DR x4852