AustrAliAn triAthlete | 45Reviewed by: the test lAB
craig Mckenzie and Patrick legge are the test lab. Two guys with an obsession for trialling all things
related to swimming, riding and running and telling anyone who will listen what they think. Having 20 years each
in the sport, they’ve seen the good, the bad and the ugly, but always loved the innovation triathlon brings to the
world stage. Craig raced as a professional triathlete, winning 4 National Duathlon titles, and has worked as an
exercise physiologist, osteopath and coach, while Pat has built a career running a personal training, massage and
coaching business, working with State, Australian and World Champions, including Australian Olympic and
Commonwealth squads whilst competing himself.surface. All of the Xtreme Carbon wheels
are explicitly designed for triathlon and
time trial (TT) events, and the forces
exhibited by such events. As a result, they
have been ratified, legal for all UCI TT and
triathlon events. NB: mass start cycling
events require depths of 65mm and under,
which Xtreme Carbon are working on for
future projects. There are also disc brake
versions coming down the line, should the
current trend become the norm.
Both the front and rear options use 24
J-pull round Sapim spokes. This allows
Xtreme to achieve optimal stiffness and
reliability. One might expect there to be
some deficit with round spokes but
Xtreme state that there is no aero data
available that confirms that a bladed
spoke decreases the aero drag for the
wheel. Furthermore, testing undertaken by
the AIS track team on round versus bladed
spokes revealed that there is ‘no measurable
difference’ in the drag experienced
between both wheels. So the extra
strength of the round spoke wins out. This
makes life a lot easier when working on the
wheels or when you need a quick change
out on the road. This brings us to the hubs.
The hubs are machined from
aerospace-grade, single-piece billet
Aluminium 6061 T6 in Melbourne, and
look spectacular. Just 25mm wide, and
with a flange depth of 100m, they came
about as a result of the designers
realising they needed a hub and axle
design that fit precisely with the aero
wheel design. Thus, this hub was
designed to tuck the spokes behind the
rim and reduce the frontal area of the
wheel profile resulting in less rotating
drag. We checked to see if there had been
any failures in the hub. Xtreme reported
that through the whole testing period,
and in the production time there had
been no instances of cracks or failure. Not
surprising as the material used is
specified for use in aircraft landing gear.
Xtreme Carbon top their hubs of with
US-based, Enduro ceramic bearings.
Finishing off the look of the wheels are
the flashy gold skewers. While they may
look bulky, Xtreme assured us they were
designed for clamping force, and there is
very little aerodynamic penalty. The
benefits of a secure wheel, especially
when you consider how tight the tolerance
is with some modern frames, far outweigh
any aero loss.
We received some wind tunnel data
from Xtreme highlighting the work they’vedone to ensure that what comes out of
their factory has been designed to limit
any losses due to drag. The tests were
performed at the SAPT tunnel in Arizona,
where the protocol was standardised
across all tests. The wheels were tested
inside a bike to predict more real-life
riding, and all variables such as tyres,
inflation pressures, wind and wheel speed
remained consistent throughout. Yaw
angles between 0-10degrees were tested,
reflecting conditions triathletes and time
trialists might come up against when
racing. The data was drawn from testing
the Xtreme wheels against several
industry-leading wheel brands of the
similar depth of 60mm.
The results showed that the Xtreme
60s had around 4.2% less drag than the
next best wheel. That equates to saving
about 3.2watts at these Yaw angles,
which can add up to considerable energy
or timesavings over any triathlon course,
and especially over 180km. We would like
to see how the 60s and 90s perform at
higher degrees of Yaw (that you might see
in races like Hawaii where a higher Yaw is
common). We suspect that the
advantages at higher Yaws with these
wheel sets may not be as significant@thetestlab
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