The Baja S4 Jacket from Klim is new for Spring 2025 and is now in its second generation. Like the rest of the Baja S4 line, the jacket is designed for hot weather, adventure riding. Overall construction is a combination of schoeller dynatec high tenacity mesh, karbonite 4 way stretch 1000D cordura, 750D cordura as well as super fabric. Overall this combination earns a CE AA rating.
Taking a look at sizing, the main thing to note here is that Klim is American cut or American based, meaning that it doesn’t quite line up with European sizing. Typically it runs larger, for example in most European brands, at six foot, roughly 215lbs, I wear a size XL jacket, but in Klim I found the XL to be a bit big on me and I better fit in a size large (basically a size down from my usual size). Also I want to note that the Klim size chart is a little different as well. The size Large is pretty true to a normal American size Large, but smaller sizes fit a bit smaller than expected and larger sizes fit a bit larger than expected, so please keep that in mind if you find yourself in between sizes.
A few details to point out, the collar is a simple straight zipper collar, no buttons or snaps, the main zipper is a two way zipper so you can zip/unzip from the bottom to add additional comfort and room for movement. There is a ton of breathability in the jacket as the entire front is basically mesh and karbonite material which is also extremely breathable. Really nicely sized and positioned reflective materials are included on each side, they are the scotchlite carbon black versions that I think look really good and also reflect very well. And lastly on the front a really cool feature that I like is that you can pull the collar open and pin it back allowing for even more airflow and comfort.
On the front there are two hand warmer style pockets, they have zippered closures and are a good size. And then on the sleeves there are even more reflective materials which again I really appreciate. The forearm also features a strap adjuster and then there is a velcro adjuster at the cuff to ensure proper fit. One last thing to point out on the left sleeve is the small pocket that is designed for a medical stat card, but it’s also a great place to store a credit card or drivers license.
On the back of the jacket a ton more airflow and even more reflective materials, and then at the bottom there is a rather large pocket that has a zippered closure and is made out of quite a stretch material so it can expand quite a bit.
Included armor is CE Level 1 D30 in the shoulders, elbows and even the back, and the elbow armor is adjustable for height/arm length. Another thing that I really want to highlight here is the mesh that is holding the back protector in place, it’s quite unique, it's called spacer mesh and the way it is designed it really promotes airflow to help keep your back cool even with a protector.
Lets move on to the internal pockets and storage, really a unique jacket here, usually you get one or two pockets but not here. We start off with a mesh drop pocket on one side, it is divided into two compartments, just under that you have top loading zippered pockets on each side, and next to them they both have a zippered opening to allow you to get inside the liner, another way to get inside the liner is the long zipper opening at the bottom. Speaking of zippers at the bottom there is also a long connection zipper to make it easy to connect to the Baja S4 pants.
Now you may have noticed that I didn't mention any external waist adjustment and that is because there isn't any on the outside but on the inside there is a draw string cord that will help you adjust the fit, it is also adjustable from the inside of the front hand warmer pockets.
Now lets move on to two really unique features, the first you access through this zipper right above the back protector, it is a pocket for a hydration pack, the Baja S4 is 2L hydrapak compatible, you will notice the button tab to secure the pak, keep in mind the hydrapack is sold separately. You can run the hydration hose a couple of different ways and you have loops to help guide the hose towards your mouth. The second unique feature is actually behind the backprotector itself, that's right if you lift the back protector you will find a secret little document stash pocket, a great place to hide important documents (like a passport), or perhaps your id or credit card or something that you don't want found as easily.
The Baja S4 offers quite a lot of features and definitely a ton of breathability, the entire jacket is DWR treated so it does shed water but if the weather gets too wet or too cold, the Baja S4 pairs perfectly with the Enduro S4 jacket that essentially becomes an overshell. It is very clear that Klim spent a ton of time and effort perfecting the new version of the Baja S4 and it really shows here in the jacket. It is definitely worth checking out. :: Damir 7/8/25
