POC are known by many for their high end products and attention to detail. This hip pack/handlebar bag of theirs is no exception to that standard — and yes, you read that right “handlebar bag.” The Hydro 4L hip pack (RRP $215) doubles as a handlebar bag. It’s a pretty good one, too — more on that below — definitely a cool bonus feature!
The Hydro 4L is, as advertised, a 4L hip pack that can carry a 1.5L bladder. As far as hip packs go, it’s on the larger side, but has been designed with a low profile. Credit to POC on that one, it definitely looks more streamlined than a lot of other packs of a similar capacity. This pack has the ability to carry water, snacks, tools, knee pads and a jacket (but heck, don’t let us tell you how to use it — get creative!). In many cases, it completely eliminates the need for a bigger backpack.

POC Hydro Hip Pack features
The team at POC must have had a lot of fun designing this one. It is stacked with clever and well-thought-out features.
Let’s start with the pack itself. This is one of the most low-profile 4L packs we’ve seen. For reference, all the photos in this review feature the pack filled with 1.5L of water, an energy bar, car keys, wallet, multi-tool, tyre levers, CO2 cartridge, CO2 inflator and a tube. As you can see, not too bulky at all. In fact, we found if you don’t over-fill it, you can comfortably run it incognito under your jersey.
The contact points on your back and hips are padded with POC’s patented shock-absorbing medium, commonly known as VPD. Meaning the pack is comfortable but also provides protection in the event of a crash.

You are able to tighten the pack one-handed using the large adjustable straps on the front. To really secure the pack, you can pull on the external compression straps on the side. We found adjusting these helped a lot. Particularly when you want a really tight fit for descending, they are easily reached to loosen for the climb when you don’t need it so snug. You can also attach knee pads or a jacket to the external straps. We really like this system as it’s easy to use and really does improve the overall riding experience.
The bladder hose has a magnetic clip. This is a little feature that keeps things neat and tidy and it adds to the overall ergonomics of the pack and is also just bloody satisfying to use. There’s something about things just clicking into place! The one issue we had was the magnetic base that the hose clips into came off easily. We ended up putting a little bit of gaffer tape on the back to secure it to the waist strap. After doing this we had no issues.
We found the 1.5L POC branded, Hydrapak bladder to be a generous reservoir. It’s always great to have the option of more when it comes to water. However for shorter rides we’d likely just fill it to the 1L mark to keep the weight down. The bladder’s sealing mechanism is very reliable and easy to use. It folds once and then a clamp is slid over to lock in the seal. Done and done. It also conveniently doesn’t leave you thinking “is that water leaking or sweat.” We love that there is no cap, just fold and seal.


Our one gripe with the bladder is that the hose can only be mounted to one side. Our reviewer would naturally reach to the other side of the pack to grab the hose. It’s a minor detail but it would be nice to see an option for both left and right-handed preferences.
The pack has three generous pockets. The rear pocket is where the bladder is stored. If you’re not using the bladder, it is a large open pocket with no internal compartments. Then there is the main pocket, which has elastic compartments, a strap and a carabiner. This main pouch is well-sized and fits everything you’d expect with ease. The compartments are appropriately spaced and keep items from bouncing around. The front pocket is smaller, with no compartments. Here we kept our wallet and car key. The kind of things you want separate from pouches that are opened regularly.
The pack can be converted into a handlebar bag without removing any straps. This is a cool bonus that we really like. The straps simply tuck into the back of the pack. You then have three mounting points to attach the bag to your bike. This added feature really gives “bang for your buck”. Any time you can get multiple uses out of something is a big tick.

Ride Characteristics
The main question asked of all mtb specific hip packs.
“Does it move around”?
Unfortunately, we haven’t ridden a hip pack (particularly larger capacity ones) that doesn’t bounce around a little when completely full. This comes with the nature of a large load being tethered by only one strap. Unless designs change drastically, a backpack will always be more secure when carrying heavier loads. However, the POC Hydro 4L is one of the most tight and tidy hip packs we have used. The additional tightening straps are a key feature contributing to this. With these, you can get the pack extremely streamlined and tight, reducing shifting as much as possible.

It does need to be noted that the movement we noticed only occurred when the pack was completely full including 1.5L of water. It gets less noticeable as you drain the bladder (we’re talking about the pack’s bladder, just to be clear), which in turn reduces the overall weight. When we ran slightly less water or no bladder at all, we didn’t notice any bouncing around.
Flow’s Verdict
We’ve come to expect high standards from POC over the years. With this one they haven’t let us down. The Hydro 4L is a hip pack for all occasions, when packed light, it’s super low profile. But it also has the ability to be loaded for big missions. The additional use of a handlebar bag is a great feature. For those that want a versatile pack but don’t want to go down the backpack route, this one will be a serious contender.