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From: neal@druxv.UUCP (Neal D. McBurnett)
Newsgroups: net.bicycle
Subject: Re: Bike ---> Cross Country Ski - (nf)
Message-ID: <1367@druxv.UUCP>
Date: Mon, 26-Nov-84 10:55:52 EST
Article-I.D.: druxv.1367
Posted: Mon Nov 26 10:55:52 1984
Date-Received: Tue, 27-Nov-84 04:16:46 EST
References: <16200079@uiucdcsb.UUCP>
Organization: AT&T Information Systems Laboratories, Denver
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It seems to me that x-c skiing is pretty close to running in terms
of effort per mile.  Of course your skill level, ski quality, waxing
technique can make large differences, but the top runners and skiers
are frequently within 10-20% of each other in terms of speed.
Naturally, inexperienced skiers will be slower (and more sore...).

So now you may ask, "well how do biking and running compare?".  Again,
depending on technique and experience, expect a slowdown factor
of between 2.5 and 3 when you start running.  This is even more difficult
to specify. The rate of energy expenditure when you run is nearly linearly
related to the speed with which you run, whereas when you bike, your
effort is related to a cubic polynomial of your speed.  Thus
the effort expended when you run is quite closely
correlated to the distance you run (regardless of how fast you run it),
whereas the faster you ride, the more energy you expend per mile (assuming
you're going faster than about 12 mph).

As for hills, in all cases (to a first approximation), the extra effort
required to go up a hill is determined by the effort required to lift
you and your gear upwards against the pull of gravity.  First, note
that your bike weighs more than your skis, so hills are more of a problem
on your bike from that standpoint.  Furthermore, note that you are
more efficient on level ground on your bike than on your skis (there
was a great Scientific American article a while back which pointed out
that the bicycle is more efficient than any other mode of transportation,
man-made or in the animal kingdom). Thus you will notice more of
a decrease in speed when you ascend a hill on your bike than when
you ski (and more of an increase when you go downhill).
As a rule of thumb, for casual biking, I find that a 3% grade cuts my
speed in half, but I'm sure that it wouldn't slow my skiing down that much.

If anyone wants harder numbers and equations, I can probably supply them.

Finally, as for muscles, I frequently pull my groin muscle when I ski:
it is stretched a lot in x-c, but not at all in biking.

-Neal McBurnett, ihnp4!druny!neal, 303-538-4852