With most (all?) serious new aerodynamic road bike wheels heading toward a rounded, bulging profile, Reynolds’ new Aero line bucks the trend by using a deep “V” profile with an almost exaggerated point.
Designed by Paul Lew, the wheels are available in 58, 72 and 90 millimeter depths, with varying rim profiles depending on length. In particular, the lip at the rim/tire interface is stepped inward on the two shallower models and outward on the 90mm.
The Aero wheels started with the RZR 92, which is a cost-is-no-object technology project. The new rim shape is called DET (Dispersive Effect Termination), which is based on aircraft design by Paul Lew (yes, from Lew Wheels until Reynolds bought them). Contrary to the rounded, fat aero wheels that are all the rage, DET aims to calm the turbulence caused by bike wheels.
Lew says the RZR 92 has been out for two years and been proven in the wind tunnel and on the road. Now, they’re taking that technology and commercializing it into a wheel line that’s more accessible. Where the RZR92 retailed for $4,500, the new Aero wheels are about half that.
Roll on in for specs, detail photos and a technical breakdown from Mr. Lew himself…
The rim shape is more rounded “V” shaped that comes to a tapered trailing edge. Lew says the blunt rounded edge on many other brands creates more turbulence behind.
Lew says this design calms turbulence on the leading part (front) of the wheel that sees clean air and that once the air passes the fork and spokes, it’s turbulent air and the aerodynamics don’t matter as much as some brands are touting.
With rounded wheels, he says other brands claim that shape reduces crosswind drag, but Lew says his DET performs at lower drag with a higher angle of attack than rims with a broad spoke face (ie., fat rounded edge). The max yaw angle before the Aero wheels stall is 17° – meaning the drag decreases to about 17°, then it starts increasing. Besides reduced drag, this lends stability to the wheels, and Lew says they’re very stable and easy to control.
Lew says they also spent a lot of time with CFD designing the hubs and spokes, going so far as to hide the round, non-bladed portion of the spokes inside the rim.
Reynolds uses different types of carbon fibers for different parts of the rim to optimize the layup for strength, weight and braking. They use their CTg (Cryo-Glass Transition) braking surface and pads, which they have shown to reduce braking temperatures up to 100°F and increase the total heat tolerance to about 600°F. It’s a combination of specific resins, carbon fibers and their CryoBlue brake pads.
At the rim’s edge, CFD showed that a step down in width on the outside of the rim before it hits the tire reduced drag for the 58 and 72 (left). On the 90 (right), it’s flip flopped with the step down on the inside edge. Why? With shorter rim depths, you want a low pressure zone behind the tire to help the air reattach. The 90’s longer rim profile has a subtler transition that doesn’t “punch” the air out away from the wheel like the shallower rims do. The designs also pull the tire in (narrower) on the shorter rims and pulls the tire wider on the 90. This gives them a bit of control over the tire’s shape even with the same size tire. They’re recommending a 21-23 width tire to maximize aerodynamics.
Rim width is 26.2mm, lacing is 2-cross on the rear and radial on the front. Weights are 1570g (58), 1680g (72) and 1900g (90). Should start shipping at the end of August.