Sportful R&D Zero Jacket

With the Sportful R&D Zero Jacket, you'll never be able to use the excuse that it's too cold to ride outside, as the excellent Polartec Alpha insulation it's made from keeps you comfortably warm when the temperature plunges below zero.

Earlier in the autumn I tested Sportful's updated R&D Light jacket and was highly impressed with its performance. This R&D Zero Jacket is essentially a beefed-up version for much colder weather but employs some of the same materials and design features. Basically, if you want a jacket for combatting the coldest weather, this is the one to go for; if you rarely go out unless the temperature is no lower than, ooh, about 5 degrees, the R&D Light is a better bet.

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The R&D Zero gets its toasty warmth from the highly impressive Polartec Alpha material, which is used to provide a full wrap of protection from the elements, used in the main panels and the arms for extra insulation. Alpha is a very light and low-bulk synthetic down and is startlingly good at providing adequate protection from the cold without restricting breathability or freedom of movement. It's combined with Sportful's WindWick LT outer face fabric for wind and water resistance, and NoRain Thermal inserts on the sleeves and back panel.

Sportful claims the jacket is good for a temperature range of 0 to 10°C, but I found I could go much lower – such as the -5°C temperature the other morning. Brrr, that was a chilly ride. Not for my torso and arms, though – this jacket was just marvellous in those conditions.

That was wearing a baselayer underneath, admittedly a chunky North Face winter one too. But it's a long way from the days when I used to wear at least three of four layers in a desperate effort to keep warm on cold rides. You can tailor the baselayer to suit different temperatures, going to a lighter one for warmer temps, and you can layer up if you feel you need more insulation, but I've not yet ridden in cold enough temperatures to warrant an extra layer.

Now it's all very well the jacket keeping you warm when it's cold, but if it's not breathable then things get can very sweaty and clammy as soon as you hit a hill. Fortunately, the Zero offers impressive breathability, and even when riding at a brisk tempo or doing hill repeats the going never got uncomfortably warm. I think that's helped by the fact that you can get away with just wearing a baselayer. There are two side ventilation ports if you do feel the internal temperature increasing, and opening the main zipper obviously dumps a lot of heat quickly.

What the jacket doesn't do is keep you dry in the rain. The outer fabric offers a level of resistance against the rain, and there is NoRain Thermal fabric on the back, but really it's not designed to keep you dry when the heavens open. A short downpour is okay, it'll shake off a light shower, but anything heavier and more sustained and you might want to think about pulling on a rain jacket.

> Read our guide to the best waterproof cycling jackets

The fit is really good too – that's a size small in the photos by the way – and the shape around the shoulders and upper arms is perfect. There's generous length in the sleeves and the double cuff design is a neat way to ensure a tight seal with your gloves to avoid draughty wrists. The lie-flat elastic hem is lined with a silicone gripper tape and it keeps the waist in place, and the pockets don't sag even when loaded.

If you don't want to let the cold stop you riding, then this R&D Zero Jacket really delivers impressive warmth, allowing you to continue for mile after mile in comfort. It's well constructed with an exceptionally good fit and some nice details, which are all factors that go some way to justifying that price. It's definitely an investment, but it'll reward you with ample insulation and decent breathability for deep winter rides.

Verdict

Wonderfully warm and breathable winter jacket, if a little pricey