Review | Castelli Alpha 150 jacket, warm and cosy

Castellli used a Polartec membrane is their Appha 150 jacket. Is the high price justified?

Staff February 4, 2026 (Last updated: April 10, 2026)

Castelli is very pleased with its collaboration with Polartec, the makers of the wind- and waterproof membrane used in their clothing. It’s also featured in this Alpha 150 jacket, which I tested over the past few weeks.

It’s a seriously warm jacket that, in addition to the membrane, also has a kind of fleece-like lining in the front panel. Combined with a high, comfortable collar, it makes for a wonderful winter jacket. That’s to be expected, as it comes with a premium price tag.

I rode with it in temperatures between 0 and 12°C—0 was perfectly manageable, while 12 felt too warm. Fortunately, you can unzip it from the bottom thanks to a double zipper. Another feature I really like is the extended rear panel, which keeps your lower back and upper glutes well protected from the cold.

I’m almost as enthusiastic about the Polartec membrane as Castelli is. It is indeed waterproof and windproof, but it still doesn’t breathe as well as a jacket without a membrane. During higher-intensity efforts, I tend to sweat more than I’d like, which leaves my base layer wet and makes you cool down quickly when you stop. That’s why I mainly wear this jacket for long, steady rides.

The Alpha is available in four colors; on the photo the Deep Bordeaux version.

Castelli Alpha 150: €339.95 / £360,- / $420.-

More information: castelli-cycling.com