Date: Tue, 07 Sep 2004 08:13:01 -0400

Author: sampere

Subject: bike wheel


The sarcasm in this will be kept to a minumum - I promise.

I ordered a couple of those bike wheel covers and got them in on
Friday. One was for work, but the other was for, let's just say that I
wanted to improve my 10 time trial time.

After installing the cover on my good bike, I spun up the wheel until my
computer read greater than 27 mph. The bike was stationary on my
stand. Only rotational motion here. I started my watch when the
computer read 27 mph and stopped when the computer read 25 mph. I also
did these measurements with the cover off.

Guess what! There is no significant difference in the two times. Why?
If the cover is more aero, as the ads say anyway, shouldn't there be a
difference in these times? Or is the aero effect just too small to
measure? And if so, what significance does that really have while
riding a bike?

Did I get ripped off? These aero covers are the rage - pro cyclists use
them if they don't use a disc wheel. Assuming drag goes like v^2, did I
make an error not accounting for translational motion too? My typical
time trial speed is 25 mph. Should I spin up the wheel to a higher
initial speed? What do y'all think? Why isn't there any statistical
difference between the two measurements?

This could be made into a decent physics lab me thinks.


From Tue Sep 7 08:25:26 2004