The zero wind tunnel option for serious cyclists

On May 10, 8:45 pm, "
wrote:

Tom Compton of analyticcycling.com, a site which
anyone interested in this subject should check out,
felt that one could do certain tests with access to a
very large warehouse building (to eliminate wind), but
never actually got to try them in practice.

Instead of a warehouse these guys used hallways:
http://www.ncbi.nlm.nih.gov/pubmed/10527317

On Sat, 10 May 2008 21:39:14 -0700 (PDT), Robert Chung
wrote:

On May 10, 8:45 pm, "
wrote:

Tom Compton of analyticcycling.com, a site which
anyone interested in this subject should check out,
felt that one could do certain tests with access to a
very large warehouse building (to eliminate wind), but
never actually got to try them in practice.

Instead of a warehouse these guys used hallways:
http://www.ncbi.nlm.nih.gov/pubmed/10527317

Dear Robert,

Testing bicycles in office hallways?

Old news.

:-)

"Scientific American," 1896, 7 lines up, left-hand column:
http://i15.tinypic.com/6jyivz4.jpg

Cheers,

Carl Fogel

On May 11, 5:41*am, wrote:

This thread and the one about optimal spoke pattern is depressing to
me. *It seems RBT has drifted into the "me too" syndrome of fans of
professional athletes. *No one seems interested in enjoying bicycling
for itself but rather looking for ways of achieving world records.

I quite enjoy cycling just for the hell of it. That's why I do dumb
things like ride track bikes around on hilly roads. It's fun. But
racing is fun too, and in my case would be quite a bit more fun if I
didn't get dropped from every road race, or finish last in every time
trial. To acheive this I could either move someplace where there are
slower racers, or I can eliminate waste from my equipment and train to
become stronger. I chose the latter two. And that gives an enjoyment
in itself.

Get out and enjoy the beauty of bicycling and forget about beating the
next guy in racing with special and more expensive equipment. *There's
much more to bicycling than competition. *In fact there's more to life
than the sports page.

It doesn't have to be expensive. That TT bike in my pics has a $139
frame and used Sora equipment. Hardly expensive!

But I agree there is more than competition. For me competition is just
one facet. And as such, I cannot fathom why some of the folks I ride
with spend hours and hours at health clubs in the winter riding
stationary bikes.

For example:

http://www.paloaltobicycles.com/alps_photos.html

Beautiful.

Joseph

On 10 May, 17:59, Tim McNamara wrote:


Not so much in terms of "publishing." You've posted a Web page is all;
that's different than publishing in the scientific sense of the word.

"Posted" maybe more accurate in this context but there does seem to
be quite a few books published by Mr Jute (who I assume is the
original poster). I dont think there are too many posters to this
forum who can claim the same.
http://www.amazon.com/exec/obidos/se...r=Andre%20Jute

On May 11, 4:05*am, Tom Sherman
wrote:
Andre Jute wrote:
[...]
My guess for cyclists of Cd = 0.50 which bothers you still seems
reasonable to me, possibly on the low side of a conservative estimate.
An automobile must be awesomely well developed to reach a Cd of 0.3.

My 1994 Honda Civic Si had a reported Cd of 0.29.

I'll take your word for it, Tom. Now name ten more cars that ever saw
a showroom with a Cd of 0.3 or under.

The human body is simply not an aerodynamic device, and in the
Aerodynamicists' Club hangs a Wanted Criminal poster for the man who
designed the safety bicycle.[...]

Careful now, the dark side is calling.

Here is a model of bicycle that reportedly (based on recorded speed and
power meter data) has a Cd of less than 0.08:
http://www.ent.ohiou.edu/~et181/hpv/lisa_Vetterlein.jpg.

Now we know what happened to Ma Sherman's molds for the State Fair
prizewinning handed monster jellies.

Of course, it
is not usable on anything but a close course in low wind conditions.

The shortage of defined edges looks like a textbook case of
aerodynamic instability. I wouldn't mind having a go in it, though,
even better, to have it for a week or a month to run some tests in a
quiet valley I know with a lane in the bottom.

Andre Jute
http://members.lycos.co.uk/fiultra/B...20CYCLING.html

"Andre Jute" wrote in message
...

I'll take your word for it, Tom. Now name ten more cars that ever saw
a showroom with a Cd of 0.3 or under.

Far too easy...

Audi 100 was 0.3 in 1982.
Vauxhall/Opel Calibra
Honda Insight
Porsche Boxster
BMW 8-series
Honda CRX
Hyundai Sonata
Toyota Camry
Saab 9-3
Lotus Elite
Lexus LS400 and LS430
Audi A2
S-class Mercedes

On May 11, 4:45*am, "
wrote:
On May 10, 7:20*am, Andre Jute wrote:



But if you think my suggestion is too much work, then that's it;
someone else will take it up sooner or later and then we'll find out
who's right. All I can say is that my method has worked for a quarter-
century for special car builders who bought my book (they write to me
to tell me so) and before that, back into the nineteenth century, for
automobile engineers and before them railway engineers, whose methods
I adapted in the light of modern requirements and knowledge. (It isn't
like I invented anything weird: I just rearranged and reapplied widely
known physics to overcome practical difficulties in cyclist
measurements.)

Cyclists operate in a different regime than cars (even
experimental cars) which make it difficult to apply
these types of tests. *It's not that the formulae are in
error, but that experimental variables which are hard
to control influence the numbers one derives.

In particular, cyclists operate at low-power, low-weight,
high importance of aero drag. *One consequence of
this is that it is quite difficult to measure Cd * A accurately
by coast-down tests. *Just as an example, if we assume
that we know all the other variables - our surface is
perfectly flat (or of known constant gradient), we know
Crr, and so on - the drag force is F_drag = 0.5 Cd A rho V^2,
where rho is air density and V is airspeed, not
ground speed. *In order to measure Cd*A to 10%,
we must know V to 5% (since it is squared).
However, if we are doing tests with the cyclist riding
at ~20-30 mph, this means knowing airspeed to 1-1.5 mph.

Well, this is extraordinarily difficult. *You basically can't
feel a wind speed of 1-2 mph. *If there is any wind at
all (even 5 mph), it will usually have gusting variations
that are above +-2 mph. *An anemometer that measures
at *about +-1 mph accuracy costs real money, approaching
what a bicycle power meter costs.

Obviously I made the problem hard by wanting CdA to
10%, but even measuring it to 20% demands knowing
the airspeed to 2-3 mph, and again that's difficult.
There are also other errors that creep in, for example
measuring accelerations requires differencing speeds
that are not always measured very accurately and
this introduces numerical noise. *This is why Chung
wants to see an error analysis of your method.

Andy Coggan, Jim Martin and others investigated
using coast-down and similar tests to see if they could
tell the difference between various aero setups, wheels,
positioning and so on - and they had a power meter,
so they actually knew what the cyclist was putting out.
They concluded, essentially, that it couldn't be done
outside.

Tom Compton of analyticcycling.com, a site which
anyone interested in this subject should check out,
felt that one could do certain tests with access to a
very large warehouse building (to eliminate wind), but
never actually got to try them in practice. *These and
other relevant thoughts have been posted to r.b.racing
and may be found by searching the archives.

Ben

Thanks for that deeply exciting list of challenges to overcome, Ben.
I'm aware of Tom Compton's site, though only recently, since it was
referenced here in the last fortnight; I notice that Mr Compton seems
to believe that the average racing cyclist with his hands on the drops
will be found to have a Cd of c0.5.

I like the Compton idea of a large warehouse... Makes me wonder if one
could liberate some traffic cones and diversion signs and claim a
tunnel through a mountain or under a river for cycling tests for a few
hours early one morning before the authorities get their brains in
gear... I regularly used to scrub racing tyres on the autobahn in
Germany, early on Sunday mornings blocking a suitable stretch with
boards silkscreened in my agency's studio and a mechanic with a flag
at each end. All it takes is a little lateral thinking, and a spot of
chutzpuh.

Long live the Cyclists' Revoluti-- er, sorry, Mathematical Front!

Andre Jute
http://members.lycos.co.uk/fiultra/B...20CYCLING.html

On May 11, 8:17*am, "
wrote:
On May 11, 5:41*am, wrote:

This thread and the one about optimal spoke pattern is depressing to
me. *It seems RBT has drifted into the "me too" syndrome of fans of
professional athletes. *No one seems interested in enjoying bicycling
for itself but rather looking for ways of achieving world records.

I quite enjoy cycling just for the hell of it. That's why I do dumb
things like ride track bikes around on hilly roads. It's fun. But
racing is fun too, and in my case would be quite a bit more fun if I
didn't get dropped from every road race, or finish last in every time
trial. To acheive this I could either move someplace where there are
slower racers, or I can eliminate waste from my equipment and train to
become stronger. I chose the latter two. And that gives an enjoyment
in itself.

Get out and enjoy the beauty of bicycling and forget about beating the
next guy in racing with special and more expensive equipment. *There's
much more to bicycling than competition. *In fact there's more to life
than the sports page.

It doesn't have to be expensive. That TT bike in my pics has a $139
frame and used Sora equipment. Hardly expensive!

But I agree there is more than competition. For me competition is just
one facet. And as such, I cannot fathom why some of the folks I ride
with spend hours and hours at health clubs in the winter riding
stationary bikes.

For example:

http://www.paloaltobicycles.com/alps_photos.html

Beautiful.

Joseph

Bit hypocritical of Jobst to decry our modest efforts after he himself
reducted a famous article for go-faster merchants. See:
http://www.sheldonbrown.com/brandt/wind.html

Thing is, though, I agree with him. I took up cycling for my heatlth
and discovered I enjoy it for its own sake, and now consider a day
wasted on which I cannot cycle for some reason.

Andre Jute
Often wrong, never insincere

On May 12, 4:43*pm, Andre Jute wrote:

I like the Compton idea of a large warehouse... Makes me wonder if one
could liberate some traffic cones and diversion signs and claim a
tunnel through a mountain or under a river for cycling tests for a few
hours early one morning before the authorities get their brains in
gear...

I have considered this. But around here at least, there is often a
stiff breeze in the tunnels. It may be constant however.

This one ought to do:

http://en.wikipedia.org/wiki/Image:TRS_070405_016.jpg

It's 7.2km long under a narrow section of Oslo Fjord. The gradient is
7% on each side.

There is so little traffic there, I'll bet you could dispense with the
cones.

Talk about a foolish endeavour. The tunnel cost an astronomical amount
of money, and was built to alleviate some of the heavy traffic that
goes through Oslo (and to service a new airport which never happened
because they decided to build it someplace else!). But it is so steep
that trucks use more fuel taking the tunnel shotrcut than taking the
long route through Oslo (according to my father in law who is in the
transport business here).

Joseph

On 12 May, 18:14, "
wrote:
On May 12, 4:43 pm, Andre Jute wrote:

I like the Compton idea of a large warehouse... Makes me wonder if one
could liberate some traffic cones and diversion signs and claim a
tunnel through a mountain or under a river for cycling tests for a few
hours early one morning before the authorities get their brains in
gear...

I have considered this. But around here at least, there is often a
stiff breeze in the tunnels. It may be constant however.

This one ought to do:

http://en.wikipedia.org/wiki/Image:TRS_070405_016.jpg

It's 7.2km long under a narrow section of Oslo Fjord. The gradient is
7% on each side.

There is so little traffic there, I'll bet you could dispense with the
cones.

Talk about a foolish endeavour. The tunnel cost an astronomical amount
of money, and was built to alleviate some of the heavy traffic that
goes through Oslo (and to service a new airport which never happened
because they decided to build it someplace else!). But it is so steep
that trucks use more fuel taking the tunnel shotrcut than taking the
long route through Oslo (according to my father in law who is in the
transport business here).

Joseph


I used the Dublin port tunnel just before it was opened to traffic for
a very successful set of CdA field tests (it was just about to be used
for a 10 k running race).
Its perfectly flat, at sea level, over 4 km long and there is zero
wind in it!

http://en.wikipedia.org/wiki/ImagePT_inside.jpg