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Discussion Starter · #1 · (Edited)
I thought it would be a good idea to get this stuff in one thread. If anybody has other test data that is no longer available online, please toss it up here. If you know of data that is available, provide a link.

If you post anything here, please reply to my *last* post so the data stays together.

The first set is from an Oct 2005 test done by Tour magazine. It used to be on Zipp's website... but no more.
 

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Discussion Starter · #5 ·
Tour Test 2005... Text


"IN A NUTSHELL
Aero wheels require attention
to detail. A low number of flat
steel spokes in combination
with streamlined high profile
rims reduce the air resistance.
Different manufacturers make
use of this recipe in different
ways. Ambrosio lags behind
because of a high number of
round spokes. Citec offers the
best compromise between
aerodynamics and suitability
for daily use. Lightweight
manufactures a spoke wheel
that is completely constructed
from composite materials—
thus, the lightest wheel in the
test is also the most expensive
one by far.

“There is never too much wind for aero wheels,” says
Olivier Mouzin, the Development Director for the French wheel
manufacturer Mavic. “Wind is good!” To demonstrate his point,
he sets up a Comete disc wheel in the wind tunnel which will
serve as a reference during testing. He closes the door to the
metering chamber and starts the generator which provides high
voltage power to the wind tunnel at the Technical University of
Lyon. The fan picks up speed. We are watching through a
window how the wheel that is set in a holding device is spinning
faster and faster on a treadmill. Then the wheel is turned against
the direction of the wind in an increasingly shallow angle.
A monitor on the control panel allows us to observe the
forces which the air stream is applying to the wheel. When the
wind blows diagonally (at 22°) against the wheel from the front
we can see proof of Mouzin’s thesis: the curve which shows the
force that is necessary to spin the wheel drops off rapidly. The
disc wheel spins almost on its own without propulsive force and
is “sailing” close to the wind. The thrust exerted on it by the air
stream and the resistance are in balance. If this were a race at
high speeds with just the right crosswind, the bicyclist would not
have to exert much energy to keep this wheel moving.
Sounds good—unfortunately, crosswind has not only a
propulsive effect on the disc wheel, but it also creates
interference because the large effective area allows it to affect the
steering as well. Consequently, the use of disc wheels is mostly
limited to rear wheels, and if the wind is too strong, they are not
used at all. Therefore, we focus our test on aerodynamic spoke
wheels that are available for prices between 700 Euro and the
incredible amount of 3,690 Euro.

Except for the 4-spokes wheel by Xentis that Jan
Ulrich recently rode during the Tour Time Trial in
St. Etienne, all wheels rely on a conventional
design with spokes which are tightened by pull.
Most of the rims—which are generally made for
tube tires—consist of carbon. These wheels offer
an array of diverse and attractive surfaces:
Lightweight displays pure technology. Zipp
integrates small indentations into the rim that are
similar to a golf ball. Mavic woos [riders] with a
graphically attractive carbon cover layer. The
volume and the depth of the rims vary
considerably and some of the more voluminous
wheels are remarkably light. The lightest set by
Lightweight scratches the 1 kilogram mark—a
stunning experience when you pick up the wheels
or ride the first few meters. The carbon wheels
manufactured in one piece beat the conventional
“Olympic Gold” spoke wheels by Tune by a few
grams.

When the road begins to ascend, weight (and not
only the weight of wheels) becomes increasingly
important for the competitive rider—unless the
weight limit of 6.8 kilogram that is stipulated by
the UCI for the complete bicycle set is not already
reached. Every gram that can be saved translates
proportionally into performance and ride time
during an ascent, and not even the tiniest
improvement can be ignored. One percent of
reduced weight during a steep ascent is almost
equal to a one percent improvement in ride time.
Light wheels offer a small additional advantage above the
weight tuning that focuses on other bicycle parts. Since
the mass of the wheels has to be moved forward and
rotated at the same time, a lower weight has a positive
effect on both contributing factors (kinetic and rotation
energy) to the overall performance. For this reason, the
table shows the measured values for the acceleration
energy next to the weights. It is, however, necessary to
remember the overall extent of this influence. At a speed
of 30 km/h the mass of the wheels represent only about
five percent of the total energy of the system that includes
the bicycle and the rider.

The low weight of some wheels should not obfuscate the
fact that the slow-down effect of the air stream on the
forward motion during a typical time trial event is overall
more significant. The rider fights against the wind
continuously, whereas he rides uphill only from time to
time. Measurable differences in the aerodynamic quality
of wheels appear at a speed of 30 km/h, but it becomes
really interesting above 40 km/h. The difference between
the best and the weakest wheels in the test amounts to
about 7 Watt (for a single wheel) at a speed of 40 km/h.
At the same performance level an athlete is thus able to
increase his speed by 0.8 km/h—which, in a time trial of
around one hour length at an average of 300 Watt, allows
him to reach the finish line about 66 seconds sooner. At a
speed of 50 km/h and with moderate crosswind, the
considerable amount of 48 Watt is necessary to counter
the air resistance of a single standard wheel with a square
rim. A moderately aerodynamic wheel such as Mavic’s
Ksyrium SL necessitates 32 Watt; the best wheels in this
test (Zipp 808) require only 17 Watt.


The enormous importance of aerodynamics at higher speeds makes it clear. Any personal best can only be achieved with
aerodynamically well constructed wheels. But which concept is the optimal solution? The leading contender on the
aerodynamics scoreboard which reflects the proportional influence of crosswind is Zipp’s “Speed Weaponry” 808. Only the
disc wheel used as a reference was slightly better. The Zipp wheel sets a new standard with its extremely high and broad
rim, and offers convincing results in situations where the wind blows from the front or side. The Zipp wheel performs neck
to neck with the disc wheel up to an angle of 12.5 degrees—however, it is not possible to determine if or to what degree the
dimples on the rim are responsible for this result. Jens Voigt who placed second with this wheel in the race Liège-Bastogne-
Liège can rejoice at any rate. His passion for breakaways during crosswind situations is supported by his team through
optimal equipment. The tall rider from Mecklenburg believes he can really feel the difference. “With crosswind these
wheels spin almost on their own,” he told us during a conversation in June, quite some time before the test was performed.
In contrast, the only 4-spokes wheel performed disappointingly. The Xentis “Mark 1” displays a rather untypical behavior.
Instead of decreasing, the resistance increases with higher streaming angles. This result also contradicts the acceptable drag
value in frontal streaming situations. Above an angle of 12.5 degrees, only the Ambrosio “Xcarbo” with its many spokes
gets worse results. This shows that the looks of a wheel do not allow reliable conclusions regarding its aerodynamic quality.
Overall, it may or may not be better to place too much value on the aerodynamic ranking list. The tested wheels are not
far apart in their performance results and all keep conventional wheels at a clear distance. Since the aerodynamic
characteristics of the various wheels show so little difference, their fitness for everyday use and practical concerns should
also become a determining factor for any purchasing decision. Such considerations identify the Citec with wire rim and an
aluminum brake surface as the clear leader ahead of all the other carbon-based competitors. Without support by a whole
team of mechanics, both the gluing of tires and the braking performance on carbon rims can become cumbersome. Based on
the test results in the various categories, it is therefore advisable to pick the wheel that offers the best match for the
particular personal requirements—or simply, the one that is the prettiest."
 

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Discussion Starter · #13 · (Edited)
Tour test 1996, using an SRM.

"The german bike magazine "Tour" (www.traxxx.de/tour) has tested 10
Aero-Wheels in the issue Nr.9 from September 96.

THE TEST:The wheels were tested on a Faggin - frame, which was
equipped with the SRM - measure technic. the special crank is a
special edition of the well known SRM - crank: with 24 "flexible
measurement stripes"("Dehnme§streifen") between crank and chain-
wheels it seizes precisely, how strong the cycler pushes and
calculates the impulse power. The computer at the handlebar records
the driving power of the cycler and the speed.

The test - cycler (Lars Teutenberg, a german professional) had to
drive several times several rounds at the exact speed of 45 kmh; after
every test the data of the SRM - measure technic were transferred on
a computer. This way all wheel - units were measured.

To create equal conditions, all wheels had the same tires with the
same pressure. a special construction on the saddle forced the test -
cycler to maintain just one certain position. The tester was alone on
the course to avoid turbulences in the air. Other given Parameters
were a chain wheel with 53 x 15 teeth ( ca. 102, 5 rounds per minute )
and a constant temperature of 22¡C.

DISCS: Very big advantage of the concurrence. 12,7 % less power
needed ( with 45 kmh ) than conventional wheels with 36 round shaped
spokes ( 2 mm ) and angular rims/ conventional rims.

In Numbers: instead of of 403 Watt the driver just needs 352 Watt and
saves 51 Watt.

CHEAP AND FAST HIGH PROFILE AERO SPOKE - WHEELS: on the second rank
are the Campagnolo 12 - spoke wheels, type "Shamal". The high profile
rim with less spokes saves 9,7 % power compared to conventional wheels
during a test. The following ranks show Mavic Cosmic, Citec and
Spinergy. The relationship between Cosmic and Shamal does explain the
similar results. The rims are equally high, but Mavic uses 16 instead
of 12 spokes. On the same niveau are the 12 spoke wheels of Citec with
very much lower rim. Ergo: the height of the rim is not the only
criterion for good aerodynamics. Fitting to this result the Spinergy
wheels ( extreme profiled rim with 8 plain carbon - spokes between rim
and hub) and the HED - wheels ( high volume rims with carbon encased,
2 x 28 spokes ) test a bit worser, because they do not manage to tame
the wind.

SURPRISINGLY GOOD: Messerspeichen/ AERODYNAMIC SPOKES:
A good result was achieved by a Wheel - set of Rigidas DP - 18 - rims
( average profile...30mm ) with 18 respectively 24 aerodynamic spokes.
Reaching the same results like distinctively more expensive
constructions the wheels take a very good rank by using a higher rim
profile and less, aerodynamic shaped spokes. Allthough the wheel can
easily be managed in repairs and is just a little bit more expensive
than usual wheels.

Until more precise tests take place it seems that 18 respectively 24
spokes can bear a weight of the cycler up to 75 kg. More spokes on the
back wheel are efficient if the cycler has more weight or takes
extreme stresses. If one takes a 40 mm rim with 18/24 spokes like FIR,
Basso and others from the beginning, the more stiff rim profile gives
enough security and good aerodynamics.

LESS ADVANTAGE: TRI - and FOURSPOKES: not many specimen tested.
Delivery Problems ( Spezialized, Habo ), production stops ( Spin
wheel, Mavic, Zipp ) and other impediments left only three wheels to
be tested. With 6,7 % less need of power Spengle takes the last rank
within the complete sets. The single Corima - front wheel, tested with
a 36 spokes back wheel is compared to the combination Shamal - front
wheel/ 36 spokes back wheel worse, too.. the results show the problems
of this type of wheel: carbon wheels are expensive and relatvely
heavy; the aerodynamics are worse than amongst the spoke wheels.


Power: Watt
45 km/h

Disks: 352,00
Shamal HPW 12: 364,00
Cosmic: 366,00
Citec 12 Spokes: 367,00
Spinergy: 369,00
HED Jet: 375,00
Rigida DP 18: 375,00
Spengle Tri-Spoke: 376,00
Shamal FW/36S BW: 385,00
Corima VR/ 36S BW: 388,00
Standard 36S: 403,00
 
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