The Duro 15 is the largest of Osprey’s three backpacks designed for trail running.
Having already tested and used the smallest pack, the Duro 1.5, I was keen to look to the other end of the size scale to see what the 15 litre version had to offer.
Features:
The first thing I noticed about the Duro 15 was the number of storage options; the pack has no less than 8 zipped pockets and 5 mesh pockets, all of various sizes! The main zipped compartment on the back can easily hold items such as spare clothes, emergency shelter, waterproofs etc. whilst a rear stretch mesh pocket with clips gives faster access to items; useful when it’s an on – off waterproof day. A smaller rear, zipped pocket has a retaining clip for keys and can fit a wallet or phone. Two decent sized side zip pockets are big enough for hat, gloves and food and are just about accessible without having to be double jointed! I found that these side pockets are also deep enough to hold rigid water bottles without them bouncing out whilst running.

rear side pockets can be reached without being double-jointed!
The zipped pockets on each hip are easily accessed on the run and provide another option for smaller items such as snacks, gels, compass, car keys etc. Finally a zipped pocket on one side of the chest is just large enough to fit a phone although it’s a tight fit if you have a full soft-flask on the same side.

zipped hip pockets are easily accessible

2 mesh pockets and a zipped chest pocket holds a phone
On the front straps there are two deep, mesh pockets that house the soft-flasks or can be used as storage (another option for accessible phone storage). They also have elastic retainers for the soft flasks and an emergency whistle. Two smaller mesh pockets below these would hold a compass, gels, electrolyte or salt tablets etc. There are also two elasticated pole loops on the top shoulders for carrying lightweight hiking poles when not in use. To be honest I didn’t try to use these as I don’t have any poles, but I can’t see that they would be particularly easy to access whilst wearing the pack.
The Duro 15 offers versatile hydration options coming supplied with two 500ml soft-flasks with straws and a 2.5 litre bladder that fits into a dedicated zipped pocket with clip to keep the bladder in position. The bladder has a wide mouth which makes refilling and adding energy or electrolyte powder easy and the hose has a clever disconnector which allows the bladder to be removed whilst keeping the hose in place. This is really useful for mid run refills and stops you having to unthread and re-thread the hose and also makes for easier cleaning. The hose has a bite valve with a twist closure to prevent accidental leakage. Whilst running the hose can be kept in place by a strong magnet that attaches to the sternum strap. This does a surprisingly good job at keeping the hose in place but has the downside that you need to keep your compass well away from it! The magnet is easily removable if this is an issue and I’d recommend taking it off if you are using a compass.

wide mouth 2.5L bladder and hose connector
If you don’t want to use the bladder, then two 500ml soft-flasks (supplied) can be stored in mesh pockets on the front of the pack on the lower chest. The long straws make drinking on the go fairly easy, however I found it quite difficult to get the full bottles into their pockets as the fit was too tight. Also it wasn’t possible to put the straws behind the straps designed to keep them in place without bending them in half (something I’m not sure is good for the straws). Osprey do make smaller 250ml flasks which are a better fit.

500ml soft flasks: tight fit and the straw is difficult to position
The Duro 15 is a unisex pack that comes in two sizes, Small / Medium or Medium / Large, mine being the smaller version. There is lots of scope for adjusting the pack with tensioning straps on the front, hips and waist plus elasticated straps across the chest that can be unclipped and attached in a number of positions.

unisex fit in 2 sizes

straps allow the pack to be adjusted to fit
The elasticated straps allow your ribcage to expand and so don’t restrict your breathing. The chest straps can be unclipped single handedly although I found them a little tricky to fasten at first. The back is slightly padded with a mesh design to help breathability and I found the pack comfortable, although as with any pack without a “back plate” you need to pack carefully to ensure that nothing hard digs in and causes discomfort.

adjustable, elasticated chest straps and magnet for hose
At a touch over 500 grams the Duro 15 isn’t a super-light pack, but this means it is more comfortable and has more features than a lighter pack. With an RRP of £140 it isn’t cheap, but it feels like it is built to last.
What would I use it for?
The Duro 15 isn’t designed as a lightweight race vest, it is more suited to longer days on the hill where you need to carry more equipment, for example mountain running in winter or in bad conditions. It would also be a good choice for multi day races and it has become my go to pack or for supporting long distance challenges, using it on the Bob Graham and Paddy Buckley Rounds where I needed to carry equipment for someone else as well as my own. I would also use it as a summer walking pack.

wearing the Duro 15 on Bob Graham support
Pros:
Loads of storage, good hydration options, comfortable, durable.
Cons:
Not cheap. Difficult to get the 500ml bottles into their pockets!
Verdict:
A comfortable pack with lots of storage and hydration options. Ideal for long, remote runs, multi day events or runs where slightly more carrying capacity is needed.
RRP £140
Available from Osprey https://www.ospreyeurope.com/shop/gb_en/duro-15-2019