Aero+

DT Swiss developed the ERC 1100 Dicut with a triple-pronged design objective, dubbed Aero+, and placing equal emphasis on low drag , stable handling and efficiency (or, in other words, comfort and grip). All are intrinsically linked in optimising a wheelset for no-holds-barred endurance riding, DT Swiss say.

A carbon fibre wheelset developed to reduce drag? Well that’s nothing new on a set of road hoops, but perhaps more significant, and relevant specifically to the ERC 1100 Dicut as a versatile endurance wheelset, is the idea of uniting aerodynamic with stable handling and efficiency.

DT Swiss say the ERC 1100 Dicut’s 47mmp-deep rim, which has an internal and external width of 19mm and 27mm respectively, is designed to offer low aerodynamic drag when partnered with a 25mm or 28mm tyre, while also offering predictable handling thanks to the blunt, U-shape profile. Comfort comes from the use of a wide tyre on a wide rim, alongside a new spoke developed specifically for this wheelset.

Staying aero

This is where the ERC 1100 Dicut’s handling characteristics come into the equation, too. Ballard says the objective was not purely to create the fastest wheel in the wind tunnel, but the fastest wheel out on the road. With the ERC within one-watt to its competitors in the wind tunnel, DT Swiss and Swiss Side set about improving the handling of the wheelset.

Any rider who has ridden an unstable, deep-section wheelset in blustery conditions will be able to attest to the nervous handling that comes as a result. Ballard says that forces the rider to sit up, out of an aerodynamic position, or ease off the power – often both – and that can result in significant time lost over the course of an event.

While low drag is important, Ballard says the graph that really matters after wind tunnel testing shows the steering moment co-efficient – or the impact of crosswinds on the handling characteristics of the wheel. Swiss Side’s testing showed the ERC 1100 Dicut to be the ‘best handling wheel in wind conditions commonly found on the road’. The smooth curve of the ERC 1100 Dicut on the graph represents stable handling across a range of wind conditions, with no sudden stalling as a result of airflow becoming detached from the rim.

The wheelset’s stable handling comes as a result of the rim width, which reduces the impact of frontal airflow (i.e. drag created by the rider’s speed) when paired with a 25mm or 28mm tyres, and the rim-tyre transition, which is subsequently shaped in a way which helps airflow stay attached to the tyre and rim.

The rim profile is also key and the curvature of the ERC 1100 Dicut’s rim is said to prevent an early stall, where the wind would otherwise become quickly detached from the rim and create unpredictable handling, with the wheel buffeting beneath you. Instead, the ERC’s profile aligns the slipstream to create a ‘sailing effect’, Ballard says.

But what about Zipp’s whale tubercles? If you missed it, last month Zipp launched the 454 NSW wheelset, with an undulating rim profile inspired by whale fins, and said to significantly improve the stability of the wheel by helping to keep airflow attached to the rim, just as a whale’s tubercles (the ridges on its fins) help keep water flow attached to enable the whale to turn quickly through the water.

– Zipp launch 454 NSW wheelset with unique Sawtooth rim shape to improve crosswind handling –

Having experimented with the idea of tubercles in Formula One on a car’s rear wing, the Swiss Side team tested it during the development of the ERC 1100 Dicut and showed us a prototype with a similar design to the Zipp, albeit with a smaller difference in height on the undulation of the rim. While Ballard acknowledges its an interesting idea, he says water has a much denser flow than air and Swiss Side’s testing shows the design creates additional drag. We have no way of varying the wind tunnel results of either Zipp of Swiss Side/DT Swiss, but it’s nonetheless interesting to note the two different directions taken by both companies.

DT Swiss’ testing, using 25mm and 28mm Continental GP4000S II tyres inflated to 6 Bar (87 PSI) on the ERC 1100 Dicut rim, showed the 28mm tyre produced 37.5 watts of rolling resistance at 45km/h, whereas the 25mm tyre produced 39.8 watts – with the wider tyre also more efficient at 7 Bar (101 PSI) and 8 Bar (116 PSI).

A wider rim also has a positive influence on rolling resistance. Using 15mm, 18mm and 19mm DT Swiss rims (with the latter being the ERC 1100 Dicut) and 28mm Continental GP4000S II tyres inflated to 7 Bar (101 PSI), the rolling resistance measured was measured at 37.6, 37.4 and 36.9 watts respectively.

The wider the better, then? According to DT Swiss, no – any improvement in rolling resistance should be balanced by aerodynamic drag. When riding at less than 35 km/h (21mph), the advantage of 28mm tyres and lower rolling resistance outweighs any aerodynamic penalty, whereas above 35 km/h (and particularly at higher speeds around 45 km/h)  the aerodynamic advantage of a 25mm tyre has more influence than the faster-rolling wide rubber.

That said, for most riders using the ERC 1100 Dicut wheelset, 28mm tyres will offer the best balance of comfort, grip, rolling resistance and low drag. As an aside, Swiss Side’s extensive testing showed the Conti GP4000S II to be the most aerodynamic road tyre out there.

The finer details

DT Swiss are perhaps better known for their hubs and spokes than they are complete wheelsets, and a new spoke has been developed for the ERC 1100 Dicut.

The Aerolite 2/3 spoke has a bladed and double-butted design to combine aerodynamic performance and comfort. The upper two-thirds of the spoke, closest to the rim and where the rotational speed is higher, is bladed to lower drag, whereas the lower third is round to offer more flex.

DT Swiss have also designed a new hubset, with a narrower axle diameter and narrow spoke flanges, to reduce drag by 0.4 watts over the regular Dicut hubset. Marginal gains and all that. Otherwise it shares the easily-serviceable, same tool-free design as other DT Swiss hubs and uses a 36-tooth ratchet design with an engagement angle of ten degrees. The hubset also has ceramic bearings.

The wheels use thru-axles at both ends, with DT Swiss updating the RWS quick-release system so it now has removable levers, potentially reducing drag again by 0.9 watts. If you remove the lever, it’s small enough to keep in a jersey pocket.

Finally, if the £1,999.98 price tag of the ERC 1100 Dicut wheelset is too hot for you to handle, this is only the first in a five-strong range of endurance wheels set to launch through DT Swiss, so expect some of this technology to trickle down next year. We’ll bring you news of those wheelsets when we have it.

What else is out there?

As we noted at the top, with endurance and multi-terrain riding building up a head of steam, a number of wheel manufacturers have launched wide-rimmed, disc-specific carbon wheelset – so let’s take a quick look at some of the competition.

The SES 4.5 AR is Enve’s take on the gravel wheelset. Like the ERC 1100 Dicut, it’s designed with 28mm tyres in mind, but Enve have increased the internal rim width to 25mm. The front wheel is 49mm deep, with a wider, rounder shape and external width of 31mm, while the rear wheel is 55mm deep, with a narrower, V-shaped profile and 30.5 external width.

The wheelset is available in clincher and tubular formats, costing £2,900 for the six-bolt clincher wheelset and £2,950 for the centrelock equivalent. The tubular versions come in at £2,700 and £2,750 respectively. All wheels are built on Chris King hubs.

First ride impressions

We had the chance to take the ERC 1100 Dicut wheelset, mounted on a BMC Roadmachine endurance bike, for two rides near DT Swiss’ headquarters on the edge of the Jura Mountains, with the first ride linking fast, flat and smooth roads with beaten-up gravel tracks, and the second on a rolling road loop. An ideal initial testing ground for the hoops, though we won’t be offer a definitive verdict until we get a test in to review here in the UK.

We can offer some first impressions, though, and regardless of the road surface, the ERC 1100 Dicut is undoubtedly a stiff, responsive wheelset which accelerates quickly and offers little detectable flex under hard efforts. They’re fast wheels, no doubt about that, and they reward riding at speed. How much faster are they than non-aero wheels? That we can’t tell you, but they spin extremely smoothly on the ceramic bearings, respond quickly to accelerations, and hold their speed as the pace ramps up.

We started out on wheels equipped with 25mm Schwalbe Pro One tubeless tyres and, while we didn’t have the opportunity to measure the rubber, it was visibly plumped up beyond its stated width. We then swapped in a set of wheels with 28mm tyres for the second gravel-strewn half of the ride and the rubber sat perfectly flush with the side of the rim.

With the tyres pumped up to approximately 75 PSI, we ploughed through a network of five gravel sections, measuring from 4.1km to 1.9km in length, and in varying condition. First up, it was superb fun, splashing through deep puddles, skidding through mud and chasing wheels as the group hacked through the fields at the foot of the mountains. Everyone returned from the ride with dirt-splattered, grinning faces – whatever you call it, this type of riding, combining road and off-road terrain, is grin-inducing fun.

The wheels more than stood up to the test, too, with the plush, oversized Schwalbe tyres offering impressive grip, and the hoops exhibiting the sharp handling we’d hope for – though, with little wind, we can’t comment on their stability in truly testing conditions. We weren’t hanging around, though, and the superb bike and wheel combination proved no slouch when pushing the pace high.

It’s a good start and we’re looking forward to getting a set of ERC 1100 Dicut wheels in to test back on UK soil. What we call ‘road riding’ is morphing in front of our eyes and, with no shortage of disc-equipped bikes on the market now coming with disc brakes and generous tyre clearance, wheelsets like the ERC 1100 Dicut look to offer an ideal accompaniment for fast riders who don’t want to be held back by the road surface or their equipment.

Website: DT Swiss