Specialized Has Two New Gravel Wheels That Redefine Its Gravel Race Tech

Specialized has released two new wheelsets under its Roval brand that are billed as a big advancement for its gravel wheel technology.

The Roval Terra Aero CLX is a deep gravel wheelset with a twist. The rim features an aero profile with the bottom of the airfoil cut off to accommodate a deep 50mm rim, while saving weight and maintaining compliance.

The Terra CLX III, conversely, is a low-profile, lightweight gravel rim designed for rough roads and big days in the mountains. The wheels are a featherweight 1,079g with valves and tape, while still delivering a claimed 21.52 percent improvement in lateral compliance for rougher terrain.

Both wheels feature the same Roval composite spokes, a 27mm internal width, and similar external widths of 38.5 mm and 38mm for the Aero CLX and CLX III, respectively. They are also both designed around 35-60mm tubeless tires.

“[The Roval Terra Aero CLX and Terra CLX III] are a focused family of wheels designed to dominate from Unbound to everyday epic gravel loops,” Specialized said in the press release.

“Both wheelsets build directly from the Terra CLX II heritage — its proven low-mass carbon layup, and real-world gravel racing pedigree — while pushing into new territory with aero shaping, composite spokes, overall wheel durability, and massive improvements in flat protection.”

Here are all the details:

Six things to know about the Roval Terra Aero CLX

• A “chopped” 50mm deep rim, with a 27mm internal and 38.5mm external rim width.
• The chopped profile is effectively a 70mm deep road wheel while keeping weight down and preserving the stability of a shallower gravel rim.
• 5.38mm hooked rim beads to prevent flats and offer maximum tire choice.
• 1,340g for the set, including tape and tubeless valves.
• 5.84 watts faster than Terra CLX II with a Tracer 45mm at 40 kph.
• Price for the wheelset: $3,400 USD.

Five things to know about the Roval Terra CLX III

• 1,079g of weight for the wheelset.
• A shallow 27mm deep rim profile, with a 27mm internal and 38mm external rim width.
• 21.52 percent improvement in lateral compliance for comfort and control in harsh terrain.
• 4.86mm hooked bead hooks for maximum tire choice and pressure flexibility.
• Price for the wheelset: $3,200 USD.

Optimizing for aerodynamics with gravel tires

The new Roval Terra Aero CLX is similar to the movement in recent years from the likes of the Zipp 303 XPLR SW wheels to much deeper, wider gravel race wheels. The Aero CLX does not go to the same extremes in terms of rim width — the Zipp has a 32 internal rim width compared to the 27mm of the Roval — but it does have its own flare in the form of the chopped airfoil aero design.

This chopped airfoil, or Kamm Tail as it is also called, is an aerodynamic methodology that uses a more conventional tear-drop aero shape on the leading edge, before cutting off the trailing edge, saving weight from the added material. In most cases, the leading edge and shaping around the widest point of an object are much more important than the trailing edge, if done right.

In the case of the Aero CLX, Specialized ran models of hundreds of different options to try to make it right.

“To engineer the fastest gravel wheel the Roval team has ever produced, the Terra Aero CLX development team began with more than 300 digital rim shapes, each created through multi- factor shape optimization models,” Specialized said.

“Unlike road-specific aero rims, gravel wheels require shapes that remain stable and predictable with wider, taller tires at lower speeds and in rougher wind environments. So each model was evaluated not only for pure drag but also for how it performed with real gravel tires moving through complex yaw angles.

“The final Terra Aero CLX rim shape delivers the aerodynamic speed of a 70mm deep road wheel while retaining the weight and stability of a shallower gravel rim.”

That final profile landed at that 50/45mm rim depth, and an ample 38.5mm external rim width, ballooning to 40mm at its widest to match the width of a 40-50mm tire.

Additionally, the Aero CLX pairs the chopped-off rim shape with new composite, flat top spokes. The wider flat-top spoke profiles are claimed to deliver 0.3 to 0.5 watt savings over rounded versions. But, more importantly, the Roval Aero Composite Spokes by ARRIS use a proprietary thermoplastic with titanium end pieces. This combination is both lighter and stronger than steel, and provides a platform built to enhance comfort and tracking in rough terrain

All things considered, the resulting aerodynamic gains from all of that development and tinkering amounted to around 5.84 watts of gains over the Terra CLX II with a Tracer 45mm tire at 40 kph.

[Note: these wheels are designed around Specialized gravel tires as their professional race team uses the two products as a system. Here is our recent review of the Pathfinder.]

Adding compliance in a lightweight package

While the Aero CLX is lighter than many of its aerodynamic competitors, Specialized took a different path than just packing all of its innovation into one wheelset. Specialized decided to add a second wheel to their launch to cover all of the performance gains they could find. ¿Por qué no los dos? To use a modern turn of phrase.

The Roval Terra CLX III forgoes most of the aerodynamic priorities of the Aero CLX and instead tries to pack all the performance, compliance, and durability of its deeper aero pairing in the lightest possible package.

Weighing in at just 1,079 grams for the built wheel set, the wheels are on the short list of lightest broadly available wheels on the market. Pair that with the same 27mm internal and a marginally smaller 38mm external width of the rim, and the CLX III is built for the gnarliest and hilliest off-road terrain, with a claimed 21.52 percent improvement in the rim’s lateral compliance, which should produce a smoother ride over the chunkier terrain.

Doubling down on those strengths, the wheels have an extra-wide hooked bead of rim is 4.86 mm, which is quite wide, especially in the face, where many wheel companies are continuing towards hookless construction. This extra width is meant to prevent flats by changing the way the sidewall of a tire with interact with a rim during a hard impact, the cause of most flats in gravel riding and racing.

Both the wheels are available now for $3,400 USD / €3.200 EUR / £3,000 GBP / $5,000 AUS for the Roval Terra Aero CLX and $3,200 USD / €2.900 EUR / £2,750 GBP / $4,800 AUS for the Roval Terra CLX III.