On Sat, 15 Dec 2007 20:48:45 -0800 (PST), [email hidden]
Quoted message said:Quoted message said:The right-hand article should illuminate the matter:
http://cdl.library.cornell.edu/cgi-bin/moa/pageviewer?frames=1&coll=m...
I assume that nothing has changed since 1869.
A modern rule of thumb for walking or running on firm level ground is
1 kcal/kg/km.
Dear Robert,
More seriously than my link to 1869 data about velocipedes, Bill's
question is how things are figured when an hour at ~18 mph on the
trainer is said to take about twice as many calories as the same hour
at ~14 mph.
Your rule of thumb is probably quite true, but the speed and distance
increased less than 30%, while the predicted calories increased
roughly 100%.
The difference is probably due to the fact that the power required to
overcome wind drag, which soon becomes the major factor, rises with
the cube of speed.
If we cube ~18/14, we get about 2.1, fairly close to the roughly
doubled calories that Bill's cyclocomputer claims.
There might be some fudge factor involved for tire drag and
transmission losses, which don't rise at the alarming rate of wind
drag.
Of course, the cyclometer may use some entirely different calculation.
Cheers,
Carl Fogel