This is what happens when you let hikers design a pack for mountain bikers. The result is generally good with some new and interesting features, but some things don't really translate, and some things are just weird.
Let's start with the basics: 5 liters total volume, 2.5 liters water bladder. The remaining space is enough to haul around whatever you need to take on a regular bike ride, or even a race. The point here is that this is a hydration pack to support your biking, not a small backpack for hauling gear.
On to the features, things that did and didn't work. Here's the one thing that stands out with this pack, and the main reason it is worth considering:
See the breathable, tensioned, suspended mesh? Oh man, does that ever make a difference here in the coastal Mississippi heat and humidity. I've been using the thing all spring and summer, and it's a joy to have a little airflow between me an the pack. Cooler, dryer, the pack doesn't get waterlogged with sweat; it's a revolution in hydration pack design. Beautiful!
Of course, this comes at a price: a wire internal frame to keep the mesh under tension. Yeah, a frame. Unusual in a simple hydration pack, right? At least it's lightweight, and it certainly works. On the down side, the rectangular frame could be a couple of inches narrower toward the bottom. Instead, it actually flares outward an inch on each side. This tends to rest on and even dig slightly into my hips while riding. Not bad, I've gotten used to it, but still. Also, this necessitates using the waist belt to control the motion of this back-mounted box girder. The net result is that you can almost hear some pedantic hiker lecturing about "You need to let your hips support your pack's weight." No, not on a bike you don't.
Which brings me to the next head-scratcher: load lifters. On a simple hydration pack? Really? Those belong on a 35+ liter backpacking pack, not here. Just yank'em tight and forget about 'em.
The sternum strap is worthless while riding. Too narrow to allow proper breathing when riding hard, and when in a crouched riding position the shoulder straps stay in place without it. Yanked that off. Worse than useless is the magnetic hose-keeper. Who has time to carefully find the matching magnet on the strap when you're dodging pine trees? Stuff the hose in mouth, gulp some water, let it drop when done. Anything more than that is asking for a crash. Oh, and even when I stuck the magnets together, they bounced apart within a hundred yards. Worthless, and now mercifully gone.
Speaking of hoses, the drinking nipple's rate is about half what it should be. Also, it's a fiddly beast: bite too soft, no water; bite too hard and the water stops. Maybe that works on a gentle backpacking stroll. Not good when you're bouncing down a trail. Replaced it with one salvaged off an old Camelbak, which has an adequate flow rate – though I'd still like something faster.
The bladder is OK. It has internal baffles which cut down on sloshing. The fold-over top with a slide-across keeper clip is unusual, but it works well. The hose routing is awkward, but with a couple of tries you can make it work. You'll want to sort all this out at home, at least before the first trip out.
Pockets, lots of extra pockets, some in the main pouch, some elsewhere. They're all pretty useful. I really appreciate the key-clip pocket inside the main pouch. The external glasses pocket is nice. It serves its intended function on the way to the trails, and once there makes a good phone pocket. A phone pouch on a shoulder strap would be better, mostly for quick camera access, but the glasses pocket is safe and out of the way. On the bottom there's a pocket for the included rain cover. Rain cover? Who'd use a thing like that when out mountain biking? Makes no sense. Having said that, the bottom pocket is perfect for a lightweight first aid kit and a space blanket: seldom used, out of the way, and easily accessed. Still don't know what to do with the rain cover. I can't bring myself to throw it away, but can't ever imagine actually using it.
Key keeper, behind TWO zippers: Good Stuff!
Color's good. Blaze orange would've been better around the edges of deer season, but this'll do. One more do-dad worth mention is the helmet holder. More handy than a pocket on a t-shirt.
Glasses pocket and helmet holder toggle gizmo. They both work well.
Finally, there's a front stretch mesh pocket for holding a bandanna, gloves, etc. It will hold some extra layers, but not very much. Maybe a pair of tights, but certainly not a fleece pull-over. A zig-zag bungee would've been a much better choice.
So let's sum this all up. It's a good start. It's a C as it came, then modified with a decent nipple it's a B-. It's 3 stars out of 5. The air-moving mesh back makes the other weirdness worthwhile, the internal frame makes the mesh back work, and the waist strap keeps it all under control. The suspended mesh is the biggest innovation in hydration packs since somebody sewed a pocket onto an an original Camelbak circa 1994. Osprey needs to keep developing this idea for the mountain bike market, because they're really onto something. They're just not quite there yet with this particular pack.
The whole thing. You can see the stretch mesh front pocket from this view. Helmet, gloves, mountain bike, and F-150 sold separately.
Bonus links:
To this pack at the Osprey site.
To last spring's review of the Osprey Talon 22. If you're in the mood to haul more stuff, this is the one. Still useful on a bike, as well as good for dayhiking, but a bit much for general trail riding. Wish this one had come with a rain cover, it might be useful here, unlike the one on the Syncro 5.