DT Swiss continues down the aerodynamic optimization path with the next stage of their wheel development partnership with aero specialists SwissSide, beyond the PRC wheels we saw a week ago. Like on the optimized aero design of the ERC 1100 endurance wheels introduced last fall, DT Swiss has again adapted & improved upon the stable aero rim shaping that SwissSide developed on the Hadron wheels, then refined the overall wheel build with optimized hub & spoke designs. The result is a family of top-level carbon wheels that match the best on the market straight into the wind, then outperform almost any other wheels in stability and lower drag numbers once the wind starts to move off at any angle. Spin past the break for the low down of the new ARC family in three depths…
DT Swiss again set out to develop an aero wheelset where head-on drag reduction wasn’t their only concern. As we saw with their endurance wheels, partner SwissSide has brought some realism to the table and identified the aero performance benefit of keeping the rider comfortable in a low, narrow position on the bike. Remember that the rider makes up 3/4 of the wind resistance on the rider+bike combo, so the more time the rider stays tucked, the better the over aero performance (and most times the higher power output the rider is able to maintain into the pedals while comfortable and relaxed.)
With improved stability comes reduced drag, but DT sought to start from an aerodynamic base point as well. While the ERC wheels went to a 20mm width for improved tire stability, lower rolling resistance & grip, the new ARC 1100 wheels stick with a more narrow 17mm inner width (27mm external at the widest point.) That still gives good support to larger tires, but also creates an aerodynamically optimized rim+tire profile with 23 & 25mm tires. In fact SwissSide recommends that if you are racing these wheels where drag reduction is your top priority they say to put on a 23mm tire in the front paired with a 25mm tire out back.
The new aero ARC (Aero Road Carbon) wheels get three rim profiles at this top-level 1100 spec (1100 essentially denotes an aero optimized Dicut subset and SINC ceramic bearings), with each of the wheel sets being developed from the hub to nipple to spoke to the rim, for a completely integrated and optimized aero performance that few producers can match. Each of the three wheel depths is also available in both rim & disc brake specific rims (with the same outer profile) and the corresponding aero hubs, all tubeless ready of course like the full DT Swiss wheel line-up.
The deepest 80mm rim is what DT Swiss is tagging as #FlatOutFast. These deep section carbon wheels are intended for those top riders racing against the clock, primarily in time trials and triathlons. They are intended for flat to hilly courses, and excel heading into side winds where they actually produced significant enough sailing effect to greatly reduce aero drag relative to riding straight into the wind. That sailing effect is said to go all the way up to -10 Watts of drag that in the right cross wind conditions will be propelling you forward even faster!
Next up the 62mm (actually 62.5mm deep) ARC rim is the true all-around. It offers almost exactly the same low drag numbers into the wind, while still benefiting from sailing effect due to its similar rim shape to excel in constant cross wind contusions. Lighter than the 80, the 62mm wheels make for a stable performer either in the bunch or for really long days out solo in the wind.
Lastly a 48mm deep version (actually 48.5mm deep) offers a mid depth aero profile that is light, responsive and still outperforms most dedicated aero wheel sets on the market. This it the wheel that has become the favorite of DT Swiss’s own fast riders from the HQ in Biel, Switzerland where it can do double duty of climbing into the steep mountains and still offer the low drag aero benefits and sailing coming down the long grades and along the windswept alpine lakes. It’s claimed to have average weighted drag numbers only 2W lower than the deep section 80s.
A big part of the base drag numbers are based on starting out with a low frontal area. Like the ERC 1100s, these new ARC 1100s get the same slimmed down Dicut aero hubshells base on the popular 240s. That new hub tech means low friction SINC ceramic bearings, aerodynamically optimized shells for both rim & disc brake versions, that new t-head straight pull spoke interface we saw before, and premium DT Ratchet freehubs.
The Disc brake wheels also get speed with DT’s RWS Plug In axles that drop almost 1W of drag per wheel to claw back some of the disc disadvantage with the QR lever out of the way.
Spoke-wise the wheels get a mix of DT Aerolite & Aero Comp spokes with a symmetrical 2.3 x 0.9mm bladed center section, although DT tells us they are working on even more advanced bladed shape designs for the future as well. Not surprisingly for an aero wheel series the ARCs also go for hidden internal nipples. It’s an obvious point on contention regarding serviceability, but DT weighed the pros and cons and with the durability they see in simulated & real world testing, the aero advantage won out.
It really all comes down to the aerodynamic performance that they developed and optimized in CFD and the wind tunnel with their partners at SwissSide. Since aerodynamic drag represent more than 2/3 of the resistance keeping a rider from moving forward in most conditions, with the wheels making up 8% of the drag on the rider+bike, there is a lot of possibility to work with.
We had a chance to watch DT Swiss test these wheels in the GST wind tunnel in Immenstad, Germany and watched as these performance graphs were generated. At each rim depth the ARC wheels delivered consistent drag figures on par with the fastest wheels available, and stability in cross winds that few companies can match.
SwissSide even showed us head-to-head verifiable testing with the ARC 1100 80 and the benchmark Zipp 808 NSW & Hadron 800+ wheels. The performance of the new DTs vs. the Zipps was almost the same with very small reactions of drag for the most part for the DT wheels and slightly better stability as the wind moves out at wider wind angles and the airfoil shape of the rim stalls (that’s where the air moving along the rim shape starts to break away and you begin to lose that ‘sailing effect’ drag reduction that happens with the best deep section wheels.) That data seems to stay true when you go down to the shallower wheels compared to the Zipp 454 & Hadron 485 as well, with both the 48mm & 60mm ARC wheels outperforming the competition.
We even had a look at the real differences in the wind tunnel with the 48mm deep wheel in both rim brake and disc brake variants, where it was clear that the disc wheels suffered something like a 2W penalty per wheel across all wind angles due mostly to their increased frontal area (remember those axles up there that brought back almost a watt) but performed almost the same in this stability tracking steering moment testing.
A lot of these improved aerodynamic results come down to DT Swiss spending quality time in the right wind tunnels with the right people (read: SwissSide). The variation here is all really small; that is to say that the Zipp 808 NSW wheels have excellent performance in the wind tunnel and in the real world, much like the Hadrons do, and now the DT Swiss ARC 1100s as well. What’s really to say is that DT has done a lot to build wheels that really do take on the best in the world, and they do it at prices that while not cheap are certainly competitive. Then on top of that they are offering tubeless rims across the board and the ability to get any of the wheel in either rim brake or disc brake variants, and with reliable, serviceable hub designs that can adapt to QR and 12mm thru-axle standards.
We will still have to wait a bit for wheel availability. All of the new DT Swiss ARC 1100 Dicut wheels are set to go on sale in October 2017, BY which time we expect to have seen DT completely unify their road wheel line-up naming around Eurobike. No matter the depth the disc brake wheel sets will sell for 2408€ and the rim brake variants will go for 2388€.
We don’t yet have individual pricing, but the wheels will actually sell independently front & rear, so you can mix and match depths depending on your style of riding. The way SwissSide put it, if you feel the need to size down to deal with more hilly or windy riding conditions, you would most benefit to running the more shallow front wheel where handling is affected and keep the larger rear wheel where you can still benefit from the greater depth. So 62/80 & 48/62 combinations could suit many riders looking for that aerodynamic edge (although there is only an average 2.3W increase in drag from a 80/80 to 48/48 pairing.)
The disc brake wheels get built up with 24 spokes, laced 2 cross front and rear with wheel weights of 690g/810g for the 48mm, 740g/890g for the 62mm, and 840g/960g for the 80mm, front/rear and have a 110kg/242lb maximum rider+bike weight limit. The rim brake wheels get built up with 16 radial spokes up front and 21 radial/2x out back, with wheel weights of 660g/810g for the 48mm, 730g/860g for the 62mm, and 800g/950g for the 80mm, and with fewer spokes have a 100kg/220lb rider+bike limit.