Xentis Composites GmbH & Co (Koeflach, Austria), have become a major force within the world of competition bicycle wheels. Founded just in 2002, Xentis manufactures state of the art carbon composite monocoque wheels for a variety bike racing purposes including road racing, triathlon, time trials, and even mountain biking.
Xentis claims to offer the "next generation wheel," and they have good reason. After initial international breakthrough in 2003, 2004 was a phenomenally successful year for Xentis wheels: victory in the Tour de Swiss with Jan Ullrich; Silver and Bronze medals for the Swiss Team at the Athens Olympics; Gold, Silver and Bronze medals at the Time Trial World Championships in Verona, the 24hour World record (813.6km) set by Andrea Clavadetscher of Liechtenstein, 2nd Place for Jan Ullrich in the 2004 Alpe d'Huez time trial, and ultimately victory at the 2005 IronMan World Championships with Faris Al-Sultan. In 2005, Xentis again had extraordinary success as the aero wheel of choice for Team Telekom.
Recent wind-tunnel testing done by a UCI Pro Tour team at the Allied Aerospace wind tunnel in San Diego confirmed that the Xentis front and rear combination is the fastest pairing of wheels in "dynamic wind" conditions. But, perhaps more interestingly, it was determined that Xentis wheels created lower rolling resistance due to their lower weight. It has to be kept in mind that, beyond aerodynamic drag, there are at least four other forces working against an active cyclist. These are:
--Rolling Resistance
--Rotational Resistance (from wheels, cranks, shoes)
--Gravity (on inclined surfaces)
--Frictional Resistance (from wheel bearings, chain, and bottom bracket)
Looking at the above forces working against an active cyclist, it becomes clear why Xentis wheels perform so outstandingly well: they're lighter, so they produce less rolling resistance; their weight is gradually distributed away from the hub so outter rim weight is considerably lower than a deep dish wheel, and this means that their rotational weight is lower; and as for gravity and frictional resistance, Xentis' low weight and DT Swiss bearings contribute to reducing the impact of these forces.
At Cadence we've done our own unofficial testing on a local, flat 8.3 mile out and back time trial course. We've compared the Xentis front/rear combination with the Zipp disc/Xentis front combination. With all other things being equal, the same rider rode the 8.3 mile course at an average of 348 Watts with the Xentis front/rear pair for a time of 18:05, and at an average of 361 Watts with the Zipp disc/Xentis front at 18:17. The surprising information gleaned from this experiment is that, although fairly substantially higher wattage was delivered on the second running, it nevertheless resulted in a marginally slower time. Although this experiment would need to be repeated several times, and although other external variables could certainly contribute to the findings (e.g., humidity/air density and changes in wind conditions), it does reveal interesting initial findings which, at the very least, show that there is no significant down-side to choosing the Xentis 4-spoke rear wheel over a rear disc. Given the other advantages of the Xentis wheelset as outlined above, it seems the Xentis wheelset is the clear choice for speed.
So, why don't the pro teams use Xentis wheelsets? That's a simple matter of economics. Pro teams use wheelsets not by choice, but by sponsors' demand. Xentis is a tiny firm that makes each wheel by hand in the small town of Koeflach, Austria. For Xentis to sponsor a UCI Pro Team would require a considerable portion of their annual revenue. And while pro team sponsorship is great for marketing exposure, that cost has to be weighed against a company's viability and its ability to continue making superlative quality products.