Sonic Ultra 35/40 Wheelset Review

Founded in 2007 in Belgium, the Sonic wheelset brand is now part of the Dagg Group, the creator of the Girs brand, among others. The latest Ultra 35/40 models are modern, versatile, top-of-the-line wheelsets that incorporate all the latest technologies in the field, featuring carbon rims and spokes, ceramic bearings, and a wave-shaped profile ranging from 35 to 40 mm—all at a very competitive price and weight. These dynamic wheels were put to the test over nearly 1,400 km. By Guillaume Judas – Photos: ©3bikes.fr

Sonic offers two lines of carbon wheels, which are both mounted on Girs bikes and available separately: the Hyper in 35, 45, and 55 (weighing 1,480 to 1,600 g per pair, priced at €1,350) and the Ultra line with wave-shaped rims in 35/40 and 50/58 sizes (weighing 1,260 to 1,380 g per pair, priced at €2,200). The Ultras are decidedly more modern, with a variable profile height designed to provide greater stability in crosswinds, an internal rim width of 21 mm—ideal for 28-mm-wide tyres— thin, profiled carbon spokes grouped in sets of three for weight and stiffness, and ceramic bearings for smoothness and durability. On paper, the Sonic Ultra 35/40 thus offers very high performance, comparable to the top-tier models already recognized in the market. Starting with their light weight, which can completely transform the handling of a mid-range bike—which often comes with wheels weighing around 1,600 g. Specifically, this represents a weight savings of 340 g for the complete wheelset (with the same rotors and cassette) compared to the bike I’m currently riding with Shimano Ultegra C50 wheels, which brings dynamism and responsiveness during every acceleration or on steep climbs. But this advantage would be meaningless if the wheels were too flexible laterally. That’s not the case with the Sonic Ultra, which stay firm and responsive without being too stiff or harsh. In short, these are very pleasant wheels to ride in any conditions, even on gently rolling roads.

The question of aerodynamics

We know just how much the characteristics of a wheelset can pique the interest of most performance-oriented cyclists. Different models are often compared based on their aerodynamic performance, with sometimes significant differences observed in wind tunnel tests at high speeds. But these differences should be put into perspective compared to the greater gains that can be achieved through the rider’s position, their clothing, and the frame itself. As a result, deep-section wheels are far from being the most worthwhile investment—aside from their contribution to the bike’s aesthetics, of course. On varied, wind-exposed routes with frequent changes in direction and variations in terrain, they can even prove to be a hindrance in terms of handling—and thus comfort.

We don’t have data on the aerodynamic performance of the Sonic Ultra compared to the competition—and thus to the 35/40 models—an average height that’s typically not sought after by those who enjoy riding at high speeds on flat terrain. However, I didn’t notice any significant difference in efficiency on my usual routes on open roads with a tailwind compared to the now-almost-classic 50-mm-tall wheels. Thanks to their 21-mm internal width (and a 28-mm external width), they prove ideal when paired with the 700×28 Michelin Power Cup tubeless tires on the test bike, as their sidewalls perfectly extend those of the tires, minimizing aerodynamic disturbances as much as possible. The Sonic Ultra 35/40 naturally offer slightly less inertia and prove to be slightly less engaging once cruising speed is established compared to taller wheels, but they’re still a long way from the behaviour of wheelsets with flat rims, which often seem to collapse above 40 km/h.

And since the wind rarely blows in the same direction as the road, the Ultra 35/40 regains the advantage in terms of stability when gusts hit you from the side. The bike is easier to control, which ultimately leads to a more relaxed ride and less fatigue by the end of the ride.

An exemplary finish

The glossy finish applied to the rims enhances the look of any bike. Here, it’s flawless. Beneath the finish, the brand logo is discreet but still visible enough to stand out depending on the angle from which you view it. Aesthetically more classic, the hubs feature direct-pull spoke flanges that incorporate the 3G technology found in Campagnolo wheels, renowned for their strength and overall balance.

Grouped in sets of three at the rim and at its lowest point (21 spokes front and rear), they are actually connected to the hubs by two spokes on the drive side and one spoke on the brake side for the rear wheel, and two spokes on the brake side and one spoke on the opposite side for the front wheel.

The thin, aerodynamic carbon spokes are tensioned evenly on both sides of each wheel, providing stiffness and responsiveness while eliminating the sensation of longitudinal stiffness sometimes found with certain wheels featuring steel spokes.

The Taiwan-made ceramic bearings feel smooth and fluid, whether you’re spinning them by hand or when the wheels are rolling on the bike. After 1,400 km, they have shown no signs of wear, whether in terms of smoothness or play. It’s hard to estimate their durability at this stage, but they already far exceed the quality of basic ceramic bearings found on Chinese websites for next to nothing.

Sharp Acceleration

On the road, the Sonic Ultra 35/40s are lively and responsive to even the slightest change in pace. Unlike some very (too?) lightweight models on the market, lateral stiffness is not lacking, and the rims don’t seem to wobble between the fork or the rear dropouts during aggressive accelerations, whether using a low gear ratio or pedaling harder.

Whether you’re hammering on the flat, sprinting sharply from a relatively low speed, or picking up speed after a tight turn, a bike equipped with these wheels never seems to lose its composure. The same is true on climbs, where their light weight works wonders as soon as you stand up on the pedals. But the Sonic Ultra wheels never feel too stiff, whether laterally or longitudinally. The tubeless setup with moderate inflation pressure (here, just under 5 bar for 28mm tyres with a total rider-and-bike weight of 67 kg, to maintain a good balance between efficiency, comfort, and traction) undoubtedly plays a role.

The cyclist’s holy grail?

All in all, I really enjoyed riding these lightweight, dynamic wheels, which are, however, a bit more robust than pure climbing wheels. Their 35/40 mm profile offers an excellent balance between stability and handling, while still performing well at high speeds.

Within the Sonic range, the Ultra 50/58 models with taller rims will surely appeal more to dedicated road cyclists or triathletes—or even racers who now typically compete at an average speed of around 45 km/h. But that’s no longer the case for me. And even if Sonic isn’t the first brand that comes to mind when considering an investment in a great pair of versatile wheels, the performance offered here should give us serious cause to reconsider.

The SONIC ULTRA 35/45 at a glance…

Pros: weight, responsiveness, stability, finish, bearing quality Cons: lack of brand recognition Rims: 100% carbon, compatible with tubed and tubeless tires – Rim dimensions: 35/40 mm high, 21 mm internal width, 28 mm external width – Spokes: 21 front and rear, grouped in sets of 3 – Hubs: CNC-machined aluminum – Bearings: ceramic – Cassette compatibility: HG, XDR – Brake disc mount: Center Lock – Weight: 1,260 g per pair – Price: €2,200