Mavic Cosmic SL 45 wheelset review

The Cosmic SL 45 is a versatile wheelset for riders “seeking the perfect balance between weight, aerodynamics and efficiency” according to Mavic.

We’re also promised a “light and lively” performance thanks to an aerospace-inspired rim shape that minimises drag, and flat double-butted spokes that improve responsiveness.

Though Mavic says the rim profile is “wind tunnel-tuned”, it doesn’t make any specific aerodynamic claims, the aim of the game being an all-rounder wheelset for year-round riding with a speed boost.

Can it mix it with the best triathlon wheels around? Let’s find out…

Mavic Cosmic SL 45 design and setup

The Cosmic SL 45s have a hooked rim with a 19mm internal width, at the narrower end out of the wheels in our 2024 group test and best with 25mm to 28mm tyres.

Though I ran mine with lightweight inner tubes, a trick Mavic has up its sleeve if you prefer tubeless is the ‘UST Tubeless’ system.

It claims the proprietary rim bed shape is better optimised for fitting tubeless or tube-type tyres so they seat better, rolling with less friction and improved traction.

All I can say is that my tyres went on very easily and I didn’t even need a lever.

All Mavic wheels are designed and engineered in France, and the Cosmic range is built in its ‘European’ factory (Romania, if you were wondering exactly where), so the close control over its manufacturing and numerous proprietary technologies means you can be sure of a high-quality product.

The Cosmic SL 45 wheelset weighs in at 1,575g for the pair, slightly more than some rivals in the same price bracket but with shallower 45mm deep rims.

If you want to stick with Mavic and go 320g lighter, then you could always go for the Cosmic Ultimate 45s instead, but they do cost around £4,000…

Ride performance

To ride, the Cosmic SL 45s felt stiff and efficient, but missing some of the excitement I felt when riding similarly or lower-priced wheels in our 2024 wheels grouptest from the likes of Parcours and FFWD.

Some of this might be down to the shallower 45mm rim and the quiet, business-like performance of Mavic’s Infinity hub, and there’s nothing inherently wrong with how they ride.

Despite being promised a lively ride, I’d says they felt smooth and assured rather than punchy.

But still, these wheels are nicely responsive when accelerating at the foot of climbs and out of corners, just not remarkably so.

Handling in wind

The wheels handled perfectly well in crosswinds, and I couldn’t tell the difference between them and shallow training wheels.

Some of this will be down to the 45mm depth as opposed to the otherwise deeper rims in our group test, but Mavic would probably claim some of it is down to its rim shape refinement in the wind tunnel.

The bottom line

Overall, I was quite pleased with the performance of the Cosmic SL 45s, and I wouldn’t have any major reason to be disappointed if they adorned my triathlon bike or road bike for racing.

As they’re a little shallower and yet heavier than some competitors in our 2024 group test, it’s just difficult to recommend them over these rival brands for triathlon, especially those that are more affordable.

For other options, take a look at the Hunt 54 Aerodynamicist Carbon wheelset and the Miche Kleos RD 50mm Tubeless wheels.

Mavic Cosmic SL 45 wheelset specs

Price:	£1,420
Spokes:	Flat double-butted spokes
Rim depth:	45mm
Internal rim width:	19mm
Tyre type:	Clincher or tubeless
Weight:	1,575g