Fox’s latest Defend 3L Water jacket is designed to go into battle with the rain, it uses a 3-layer fabric that blends polyester and elastane, and that gives it a flexible fit that moves with you as you ride.

Sandwiched between the inner and outer layers, and providing the waterproof and breathability functionality is an in-house membrane. This is similar to most hydrophilic polymers, and it has official waterproofness and breathability ratings of 10k. Plenty of jackets have higher marks here, meaning there’s something else going on that makes the Defend 3L one of the best mountain bike jackets out there. The third layer sits closest to your body and is in charge of wicking away moisture.

With a dropped hem and loose fit the Defend is very much mountain bike specific

All told, Fox has made a pretty weighty jacket, it’s twice the weight of the Scott Explorair Light Dryo 3. This means it’s not that packable, unless you have a big pack, and is more something you’d wear from the outset on really dirty days.

Fox does say the Defend has a DWR coating to help repel water, dirt, and debris. However, it’s not specific about whether this is PFC (fluorocarbon) free DWR as most modern jackets now are. Water did pool in big droplets on the surface fabric, even after we washed it a couple of times, so whatever type of DWR it is, it’s working.

The Defend’s hood will fit up and over your helmet, or you can snug it down with the velcro strap and cords

The Defend has a big over-the-helmet hood that comes down a lot lower than most. There are two side cord adjusters to get it snug but I had a little issue with their activation. There’s a toggle that you press to unlock the cord, but it’s buried inside the jacket and quite often it wouldn’t hold properly. It might be a pilot error but it’s not easy to operate wearing thick winter gloves.

At the wrist Fox uses a basic hook and loop or Velcro adjustment and you can get these properly tight to keep wet from seeping up the sleeves. The cuffs are also angled for comfort and to provide a bit of glove overlap. There’s plenty of girth in the arms for elbow pads and Fox adds an extra layer of Cordura on the high wear and high crash zones for durability.

Waterproof zippers are essential on a full on waterproof jaket like the Defend

Unlike the Scott Explorair Light Dryo 3 and Alpinestars Sierra jackets, the Defend is much longer in the tail. It also has a single waist adjuster that allows you to snug up the hem, to stop mud and trail splatter getting in, and it’s something you can do with one hand.

The jacket comes with two zippered hand pockets and two underarm vents for dumping heat. Both have waterproof zips. The same is featured on the front of the jacket, supported by a wide storm flap.

With Cordura elbow patches the Defend is built to fend off crash damage, although thankfully we didn’t manage to put it to the test

Performance

I’ve said it previously when testing waterproof jackets, but performance is dictated by the type of bike you’re riding. If you’re riding an analogue bike you’ll be working hard and generating a lot of heat, and wearing the Defend means you will have to wear fewer layers or overheat. With its pit vents and main front zip you can vent a lot of that heat, but it still runs pretty warm. On an e-bike you’ll be working less and often have to add extra layers, and it’s here that the Defend feels spot on in terms of breathability.

There’s a high collar to the Defend and it’s bulky round the neck, which is great in nasty weather, but less so if you’re trying to squeeze it into a pack

The hood is tricky to get right and there’s a lot to it. Done up tight you can also see the edge of the material when riding. This jacket is also pretty bulky around the neck and the wetter it gets the heavier it gets.

But it’s here the Defend really starts to shine. Water pooled in big droplets on the surface fabric and, while there was some wetting out on the sleeves after several outings, it proved drier than most. This is a jacket I’d wear for wild moorland rides when venturing up into those bleak northern hills or even in the lowlands when the weather is rough.