OMM Sonic Jacket review – featherweight windproof

If you’re looking for the best jacket for gravel riding and bikepacking, instead of trying – and failing – to find one jacket that maximises waterproofing and breathability, you could supplement your not-so-breathable waterproof with a featherweight  highly breathable windproof. This means that when it’s too chilly or breezy for just a jersey, you don’t have to pull on a full waterproof to stop your core temperature being whipped away by the wind.

There are plenty of options, from the generic windproof cyclists’ gilet, through to the perennially popular 200g Pertex Buffalo Windshirt. But if you want to keep it super light and long-sleeved, something like the 50g Sonic Jacket from adventure running brand OMM is worth your attention. As small and light as an energy bar, and as thin as parachute material, in testing I found that it packed a ridiculous amount of wind protection for something you can hardly tell you’re wearing.

Design and specifications

OMM’s kit pushes the boundaries of what you can get away with in the name of light weight, and the Sonic Jacket is one of the very lightest on the market. The nearest equivalents from specialists like Rab and Montane are typically closer to 100g.

Not surprisingly, the ripstop PointZero fabric is extremely thin, and the jacket’s features are minimal – there are half-elasticated cuffs and waist hems, a water-repellent coating, a neat collar that doubles as a tiny pouch for the jacket, and thumb loops that keep the jacket partly over your hands while you’re running. There’s no hood, no pockets, and naturally for a jacket that wants to maximize breathability and has no pretensions to waterproofing, the seams are not taped.

The cut is slim enough to not flap, but with room for a couple of thin layers underneath, and even though the jacket is designed primarily for runners, the rear hem is long enough to not ride up on a bike. The one feature that doesn’t work for cyclists is the thumb loops in the cuffs – they pull too tight on a bike.

Performance

I don’t know if you’ve ever had to look after a baby, but at first you’re petrified about how fragile you think they must be, and then you chill out after a while. The Sonic Jacket’s a bit like that – you think the soft fabric is going to snag on the first rough thing it touches, and then you realize you can chuck it around quite happily. It’s fair to say that I didn’t crash in it or subject it to too much undergrowth, but so far so good.

On the bike, the Sonic jacket was every bit as good as I’d hoped in terms of windproofing, and really showed how much heat you can lose through wind chill. I mainly used it in temperatures of around 6-12C / 43-53F with a thin or medium base underneath.

One really nice combination in colder weather was with the lightweight Rab Alpha Flash jacket underneath. In one way that was like a poor man’s Castelli Unlimited Puffy Jacket, which also has a Polartec Alpha fleece layer and a windproof shell, but in another way it was far more flexible because you could wear the layers independently if you wanted.

Breathability was good – better than any waterproof I’ve used, if perhaps not quite as airy as I’d hoped when the sun came out or on tough climbs. In other words, I wouldn’t leave it on when a base or jersey would suffice, but then why would you. 

And it’s been better in the rain than I’d expected, not that it’s designed as a rainproof. The rain soaks through pretty quickly but I’ve stayed surprisingly dry and comfortable even in those situations – presumably because my base layer could still wick and the jacket could breathe.

On a recent mild-weather bivvying trip, the Sonic Jacket worked just as I’d hoped. It was small enough to take alongside a proper waterproof, and I wore it most of the time, benefiting from the breathability and wind protection; only needing to pull on the waterproof when the rain really closed in.

Surprisingly, the fine fabric didn’t snag in the zip as I half expected it to. The only real niggle was that on some days the fabric clattered in the wind around the shoulders.

Verdict

I wouldn’t say OMM’s Sonic jacket is up there as a must-have shell for cyclists – it’s niche, bare bones and functional, and just one way of approaching the question of layering and breathability. But its tiny size, nice fit, great windproofing and decent breathability does make it a good backup jacket, a smashing option for weight weenies, and a flexible option to take with a rainproof on multi-day adventures.

Tech specs: OMM Sonic Jacket

• Price: £80
• Weight: 50g (small)
• Sizes: XS-XL (in men’s and women’s versions)
• Colors: Black, grey (tested), yellow, blue (men), purple (women)
• Materials: 100% nylon