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Aerodynamics
for Your Average Joe
John
Cobb
If
you are an elite or top age-group racer, then
aerodynamic positioning and equipment should be
important to you. But what about the “average Joe”
who rides under 20 mph, or even 16 or 17 mph?
Will better positioning and equipment really make
a difference? That is something I was challenged to find
out, as customers always ask that question trying to
justify spending their money on some new gadget that has
become available.
On
various “forums” on the internet there is rampant
speculation about aero effectiveness when positioning
and equipment such as disk wheels are applied to very
average racers. I set up some guidelines to work in and
began a search for my test mule. I ran a small ad in
Bicycling magazine looking for volunteers for this
project, and about 1200 people had sharp enough eyes to
find the ad and reply, so we weeded our way through the
applicants. My volunteer ended up being a young man from
Texas who had no cycling background other than riding
around the neighborhood with his wife. Because of the
onset of middle age and some encouragement by his wife,
“Joe” had decided to give cycling a go. Our victim
was about to buy a bike anyway so after talking with him
he went out and made his purchase. Part of this deal was
that after riding for 1 week he would go out and ride a
conscientious 26 mile time trial.
We had talked about how to have some controls in
place so the test meant something, trying for very
similar wind conditions, temperature and time of day. He
would be repeating this test the following weekend so
the numbers would be pretty comparable.
Joe
had chosen a new Raleigh road bike that fit into his
budget; it had an aero down tube and was outfitted with
Profile aero bars. His local bike shop had set him up so
he was race ready, all he needed was a few hundred miles
of training. Our young racer showed up at the Texas
A&M wind tunnel to learn how we developed more
speed. Before I started on him, I had to finish up some
work I was doing on another local Texan, Lance
Armstrong. This gave Joe a chance to see what things we
did to the top riders and make some observations about
his bike setup. We
finally started on Joe and the first thing we did was
establish a base line of performance. Joe could average
about 150 watts for the 26 mile ride so with that we
needed his aerodynamic drag to predict his improvements.
Putting the bike in the wind tunnel just as it had been
ridden 2 days earlier, we found that Joe and his bike
had an aerodynamic “drag” of 8.050 pounds. That was
using his aero bars in the position he was originally
set up on. The next thing we did was to tell Joe to do
anything he could think of using his original equipment
to get more aero. He thought about it after having
watched us work with Lance and made some changes to his
bike. His efforts netted him some good gains and lowered
his drag down to 7.614 pounds, which would have made him
just over 1 minute and 18 seconds faster. That was very
encouraging and also was going to make it pretty hard on
me. This story is not just about me “blowing my own
horn”; I wanted to show how effective wind tunnel work
can be. Fortunately, I was able to improve Joe’s
position further, while keeping him in a powerful and
comfortable zone. I lowered his aerodynamics to 6.580
pounds using only his original equipment, by tweaking
his elbow width, setting his hand and bar height, and
adjusting his loose clothing and knee position. His new
time potential was 1:16.14 so I was really looking
forward to his real world test in the next few days.
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Positioning
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Pounds
of drag
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Time
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Original
setup, with hands on hoods
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9.38 @ 17.6 mph
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1:24:32
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Adding
aero bars
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8.05 @ 18.4 mph
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1:20:49
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Joe’s
changes
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7.61 @ 18.7 mph
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1:19:31
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My
final positioning
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6.58 @ 19.5 mph
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1:16:14
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To
understand why positioning and equipment made such a
difference, I am going to start by explaining drag.
Aerodynamic drag is measured in pounds per square inch,
which means that for every inch of you or your bike that
is exposed to the wind, there is a pound of resistance
pushing against you. We reduce drag by making you
“smaller” (e.g., tucking in so that less of you is
exposed to the wind) or by making you and the bike
“smoother” so that the oncoming air flows around you
better. With less drag, you will go faster because your
effort is contributing more to your speed and less to
pushing a bigger object through the wind.
We
reduced Joe’s aero drag by over 30%, however the real
test came out on the road. A few days later the weather
cooperated and our racer went to the course. He set a
time of 1:16:30, but blew up a little early because of
too much enthusiasm. We all thought this was a pretty
successful test and was indicative of the results we
generally see. You always have to train hard and train
smart, but there is technology out there that will
really help you. Not everyone can go to a wind tunnel to
get set-up, but everyone can ask questions and read the
various technical articles to improve their riding.
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