Shimano is best known for its hardware – be it for cycling, fishing or rowing – and shoes. Its new range of bags, which includes this 10-litre pack, the Unzen, is unlikely to change that, but their visually striking designs and innovative features may well extend Shimano’s reputation to backpacks.

The most obvious innovation on Shimano’s Unzen pack is the ‘X Harness’ strap. Our initial reaction to this was: why? When every pack in history has used the same two-vertical-strap design, this seemed like pointless fiddling for the sake of market differentiation.

And then I put it on, and was instantly converted. Never before has a pack felt so right. It felt snugger, better fitting and more secure than any other pack I’ve worn. And at just around 600g (Shimano claims 570 for the 10l on test here, my scales say 630) it’s feather light too.

But be aware, the Unzen’s X strap ‘lifts and separates’ like a Platex Cross Your Heart, and it’ll enhance your assets in a similar fashion too. This may be fine with female riders, but guys if you have moobs X Harness will enhance them similarly, and it’s not a good look.

Shimano’s marketing folks claim that having a separate compartment for the hydration bladder prevents it taking up room in the main compartment. The hydration pack is still within the overall confines of the pack, so which compartment it’s is in makes no difference to how much it reduces overall available volume.

Having it in a separate compartment does work well from a usability point of view. Frustratingly though, the bladder supplied is actually longer than the drop from the bottom of the suspension loop to the bottom of the pack, so once filled, it lolls loosely to one side or other. The suspension loop uses a single press-stud closure which is likely to become less effective over time, and is a little tricky to close as it is located at the very top and centre of the side-opening compartment.

The Unzen can be adjusted to fit to your back length. The adjustment is a little fiddly though – it involves unzipping the hydration bladder compartment and moving a “yoke” up and down the back panel of the pack. The yoke affixes to the back by Velcro, and then a Velcro strap affixes on top of it to further secure it.

Because the hydration compartment is narrow, and you have to access if from the side, doing so curves the back of the pack, making it tricky to get the adjustment exactly right. When the pack arrived, the yoke was buckled, and no amount of adjustment I did would make it lay flat. In reality this did not matter at all. When wearing the pack, which has a padded back-panel, I could not tell that the strap was buckled in the bladder compartment. You only need to perform this adjustment once – so it’s not a major concern, just a niggle.

The material of the pack is a slightly wet-look elasticated fabric that manages to look both technical and slightly fetishistic. I love it! Some areas have a web/mech texture to them, and this combines with the black/red colour way make this look like one of Spider-Man’s accessories. Pretty stylish.

The ol’ web-slinger couldn’t choose a better pack for close fit and free-movement either. Shimano makes no specific claims to water resistance, but every ride I have taken the pack on has been extremely wet and muddy, and it has kept the contents; including an iPhone, wallet and car key-card in the outer pockets, surprisingly dry. It’s not experienced extended direct rain though, and we suspect the contents will need extra protection in that situation.

The pack looks best when it’s full, since pulling the material taught looks better, and gives the pack a more purposeful shape. When only partly full it has the appearance of a semi deflated balloon, and its shape is less sleek.

Access to the main compartment is provided from both sides by a vertical zip at either side. Using both together is impractical, because it becomes more of a belt than a bag if you do so. You are expected to choose the side that best suits your handedness, and which shoulder you prefer to sling the bag from, and use that exclusively. Inside the main compartment, but affixed to the back of the bag are thee pouches that can be used for tools, two of them mesh, and one made of the latex-fetish fabric.

There are two additional compartments, at the top a plush lined one for valuables, phones and so on. This would be ideal for media players, but it lacks a headphone cable port. At the bottom, a small pocket has a mesh divider and a plastic clip on a ribbon that can be used to secure keys. All closures feature zips with large cable loops attached, making them easy to operate with gloves on.

Storage is rounded out by two pockets, one on each strap. These have velcro closures, and are ideally sized for an energy bar, but could hold a small phone or a multi-tool. Because of the X-Harness design these end up being a long way round your back, so they are not as easy to access as traditional strap pockets, but they can be reached without needing to take the pack off.

Drinking from the bundled Hydrapak bladder is much harder than I could tolerate. I had to suck hard to get a flow that was still much less than any of my other bladders. The bladder can be turned inside out to facilitate washing and drying, but that’s not as easy to do as I had hoped either.

The tube can’t be easily detached at the bladder end (as it can with some Platypus bladders and according to their website, other Hydrapak models) so it is a hindrance when reversing the bladder. And the bladder has seams at the bottom, so even when it’s inside out, there are crevices for micro-organisms to shelter. The bladder is also very long, and narrow, so I could not get my (admittedly pretty large) hand into it to grab the bottom to reverse it. It’s a great idea, but not a perfect first attempt. I’d swap this out for one of my Platypus bags immediately, or buy the Unzen without the bundled bladder.

Once dirty, the Unzen sheds dried-on mud unlike any other pack I’ve used. This sounds like a good thing, but in practical terms it wasn’t. I tend to load my pack before a ride in the kitchen or utility room, and as I loaded the Unzen, it dropped and flicked mud everywhere. My current pack doesn’t do that, maybe because it is a top loader, or maybe because it’s made from more traditional woven fabric. Unless you wash your pack down after every muddy ride, or load it up in the garage or outdoors, this could be an issue.

The Unzen is an interesting pack. Absolutely comfortable to wear, and stunning to look at. It valiantly tries to move pack design forward with some innovative ideas, most of which are well conceived and valuable, but not all of which are perfectly realised on this version.

I find its combination of good looks, light weight and great ‘feel’ irresistible. To live with it, however, I’d have to swap out the hydration pack, and wash it after every ride. It would be an incredible hassle to dry it when I ride every day, but it does look way better when its clean. Maybe I’d use another pack for commuting, and keep this for weekends.

If you decide to commute with an it, and I generally use a 15-litre pack for that purpose, the Unzen’s stretchy fabric enables it to accommodate the pair of Vans, jeans & t-shirt that I sometimes find a tight squeeze in a nominally larger bag.

Verdict: I am completely smitten by this pack’s looks. Despite a few niggles and a high(ish) price, I’d have one. I’d forego, or replace, the bundled hydration bladder, though.

More info: Shimano Unzen

UK supplier: Madison Cycles

Weight: 570g (claimed) 630g (our sample)

Price: £90

What Shimano says about the Unzen hydration pack

Beneath its deceptively peaceful surface, Mt. Unzen in southern Japan hides the awesome explosive power of a volcano. It was the hidden primal force of this mountain that inspired Shimano to create the Unzen hydration pack collection. With no excess straps or bulk to hold you back, Unzen bags are specifically designed to power an aggressive off-road riding style. After installing your hydration system, just throw in your tools and favorite energy bar. Fasten the Rider Fit X-Harness. And head for the hills. The body-hugging fit of Shimano’s Accu3D technology frees you to follow the path less cycled. So if you’re ready to unleash your own hidden power, try Unzen by Shimano.

Stretchable Body
Thanks to the unique stretchable main fabric, the backpack is expandable without the use of extra fasteners that add unnecessary weight and bulk. The aerodynamic 3D stretchable body makes sure the wind flows smoothly over the pack while riding at high speed.

No Loose Straps
We made sure that our ACCU3D hydration packs have no loose straps anywhere. The only straps that are necessary to adjust the harness have a storage pocket to make sure they are invisible to the wind.

Easy Side Access
No need to take your pack completely off when you need to access your things fast.

Felt Lined Valuable Pocket
To safely store your valuable items without scratching them, this pocket has a soft felt liner. The bright color helps to locate your things easily.

Key Holder
Front pocket with key holder.

Stretchable Side Pockets
To store your bars and gels for quick access while on the move.

Armor Storage (U10 & U15 Only)
This very lightweight and easy to operate structure quickly holds your protectors or a jacket on the way without adding too much extra weight or bulk.

Loop Zipper Pulls
Very easy to operate even when wearing full finger gloves.

Tool Organizer
Located in the main compartment to keep things organised  Tools, tubes and pumps fit in here to provide quick and easy access on the trails.

Light Loop
Reflective elements and a blinking light attachment loop are essential details to provide a peace of mind when caught in the dark close to traffic.

Separate Hydration Compartment
To prevent the hydration system from taking away storage space from the main compartment and to provide quick access.

Hydration Tube Holder
To avoid the tube from flapping around while on the trail.

Reversible Hydration Reservoir
The Unzen collection is fuelled with high-end hydration systems provided by Hydrapak. The Reversible Hydration Reservoir flips completely inside out, making it very easy to clean and dry. The Slide Seal closure system is simple-to-use and effective. To prevent the growth of bacteria and mould FDA approved BPA free TPU material is used throughout the reservoir, tube, and bite valve. The 45 degree angle Surge bite valve allows drinking without effort.