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First Look: DT Swiss ERC 1100 Aero+ Carbon Road Wheels

Last week we visited DT Swiss in their Biel/Bienne, Switzerland global headquarters to get an up close look at their newest road wheels.

The disc brake-only ERC 1100s are designed to redefine the top of the growing Endurance Road segment for everything from long granfondo rides and races to all of the dirt and gravel back roads your own neighborhood has to offer.

Introducing the New ERC 1100 Wheels

Said to be the first of many in their major road wheel makeover for 2018, the new ERC 1100 wheels grow wider than any of the current DT road catalog. They also mark the first development partnership with aero specialists Swiss Side to bring an entirely new perspective to aerodynamic wheels, and one that can actually be felt (or rather not felt) out riding in the wind. Everything is new in the wheels from hubs to spokes to the rims, and offers hints of what more is to come. Check out the details, price tag, and how surprisingly soon they will be available… courtesy DT Swiss, riding photos by Michael Riehle

DT Swiss Road Revolution

We visited DT Swiss to get a first hand look at the new road line-up that they have been working on. DT is making a pretty big claim by calling their model year ’18 road wheel range a #RoadRevolution. But with some of their top-end road line slow to make the shift to wider internal rim widths and more optimized aero sections, the new ERC 1100 offers a glimpse of what is about to change for DT.

To be fair DT Swiss has been pretty ahead of the curve on several fronts for some time. Based a lot on their modular hub design giving them flexibility, DT were one of the first of the big companies to offer disc brake wheels for road and cyclocross, thru-axle compatibility with pretty much every standard, and one of the only companies that makes disc brake road wheels that can interchange between Shimano/SRAM 11 speed cassettes, Campagnolo 11 speed, and SRAM’s XD driver (all tool free, too.) Their other big thing has been road tubeless. They don’t brag much, but literally every road (and mountain) bike wheel that DT Swiss produces is tubeless ready, and has been for some time. That tech all carries over in the new wheels, but everything gets turned up a notch with this fresh look at aerodynamics.

A New Perspective on Aerodynamic Wheels

The key feature of this new premium wheelset though, is probably that it is targeted not at the pro or weight-weenie racer but at the real amateur road rider who is out putting in the kilometers and happy with the rebirth of road riding on any surface you can find. Don’t call it a gravel wheel (although it seems like it can really handle that too) but rather an Endurance wheel, making it the kind of all-around wheelset optimized for everyday riding out on real roads; not something designed on paper for some perfect road or wind conditions, or even designed for unrealistically high pro-level average riding speeds.

Swiss Side Aero+ Development

Swiss Side Endurance riding to DT Swiss means spending long hours in the saddle, and often times spending good portions of that either out in the wind solo or leading a small group of riders. They saw that as a reason to think about how to optimize the ride of the wheels, not only from a performance, durability and weight perspective, but also with regards to aerodynamics. And DT recognized that they are really more of spoke, hub, then wheel building specialists (that is where they got their start, respectively), so they reached out to the best aero experts they could find – Swiss Side, who have been establishing themselves in cycling much as they did in F1 motorsports racing.

Swiss Side brings a technical aero development perspective that is rather unique in cycling, combining several types of analysis and real world data collection, with the goal from F1 of doing whatever it takes to deliver the fastest overall system in the end. They start with CFD in the computer, before transitioning to the wind tunnel. But in what is still rather uncommon in cycling, they then transition to a lot of real world riding, collecting data on the fly to analyze more of the complete rider and bike system, rather than focusing exclusively on the wheel or even wheel+bike combo.

The Importance of Stable Aerodynamics

The result of the Swiss Side development collaboration is what DT Swiss is calling Aero+. That means not that it is designed for plus sized tires (DT thinks the best aerodynamics of the wheels are with 25-28mm tires) but rather that you have to look at aerodynamics from more than one perspective. Their take on it is that it’s a balance of low drag numbers, stable & comfortable handling, and overall efficiency. That means that as much as they were trying to lower the amount of wind resistance of the wheels, there were other key elements that affect how fast the wheel carries you.

The biggest innovation that came out of the development was the importance of stable aerodynamics. While many wheels perform well directly into the wind, or even sailing into cross winds, every wheel comes to a point in cross winds where the wheel stalls. And that transition from when air smoothly moving against the wheels to it becoming turbulent is the unsettling feeling you get in the handlebars where the wind goes from gently pushing your entire body to the side to the bar snapping back quickly in your hands. The key to stable aerodynamics then is a smooth transition from the wing-like section of the rim being pushed sideways by the wind to the point where the air rushing over the rim breaks apart and becomes bumpy. You can see on either end of the graph above that abrupt transition from sailing:stalling that occurs both in the modern crop of performance aero wheels (white) and the traditional V-shaped aero wheels (blue). That jump is the same jump that you feel in the handlebar and what makes you tense up when wind gusts pop up.

Increase in Aerodynamic Efficiency

DT Swiss and Swiss Side worked together on their new Aero+ ERC 1100 wheel to ensure that transition happens more smoothly (red curves), and this result in a dramatic decrease of that scary feeling you get riding in windy conditions. The rider makes up 75% of the overall system drag, so looking at the complete bike and rider perspective this has a big input in overall aerodynamic efficiency. Swiss Side did a lot of real world data collection and realized that every time that one of the jarring wind gusts would hit a wheel, the rider would tense up and both sit up higher a bit and ease off on the pedals. They say that riders tended to sit up between 15-20mm with each occurrence and reduce their power output by tens of watts as well. As a general rule Swiss Side said that every millimeter that a rider sits up they lose about 1W of power. In their on-the-road testing they saw this tensing happen 2 or 3 times every minute over the course of hours long rides, with the differences adding up to minutes lost. So the result was that by eliminating this jarring movement at the handlebars they could improve overall aerodynamic efficiency just by allowing the rider to comfortably stay in their more aero position on the bike longer.

Rims

The UD carbon rim shape was developed with a 19mm internal width to deliver the best performance with either a 25mm or 28mm tire. These look to be the tire sizes getting the most development right now, and provide a balance of ideal aero benefit with the 25mm tire above 35km/h and lowest rolling resistance with the 28mm tire below 35km/h. The wider rim bed is key to proper support for wider tires, so they don’t just balloon out and become unstable but also yields a more aero interaction between tire & rim. With the taller, stable…

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