For fast-paced activities like mountain biking and trail running, you need a low-capacity hydration pack.
Fabric
Lightweight ripstop nylon and polyester fabrics predominate.
Harness
Back panels consist of open or die-cut foam with ventilation channels to aid airflow and moisture-wicking. The harness works with the shoulder and sternum straps to keep the pack stable and close to the body.
Storage and capacity
While some hydration packs have capacities over 10-litres, most are smaller, designed to hold essentials like food, hydration, bike tools and an extra layer or two. Slim-line pockets and hipbelt pockets hold energy bars and basic cycle tools. Bike packs should have a helmet attachment.
Shoulder straps and hipbelt
Moulded foam straps provide comfort. They may be perforated or die-cut to save weight and be covered with a mesh fabric that helps wick sweat and promote quick drying. Smaller packs may have a sternum strap rather than a hipbelt.
Reservoir, hose and bite valve
Made of polyurethane or food-grade plastic, reservoir volumes are typically between two and three litres. The bite valve prevents water from dripping. Some reservoirs have an on/off valve.
Cleaning the reservoir
Wash and dry the reservoir after use to prevent mould. This is especially important if you have used a sweetened electrolyte drink. Those who use their packs often might want to invest in a purpose-built brush for the hose and reservoir – though slide-top models allow you to get your hand inside to do the job. Dry the reservoir out of direct sunlight and in a way that allows residual water to run out.
Now you know what to look, it’s time to choose a pack…
 Osprey Duro 6 $199.99Running pack with vest-pack fit, harness pockets, 1.5-litre Hydraulics reservoir, soft flask compatibility, bounce free carry, dual accessible stretch mesh pockets, zippered access to main compartment. Fabric 70D ripstop nylon Capacity 5-, 6-litre Weight 505g (sml), 540g (med). www.ospreypacks.com |
 CamelBak Rim Runner 22$189.99 Diamond mesh harness, removable webbing hipbelt, organiser pocket, side pockets, four point compression, lashing points for extra gear, reservoir included. Fabric 70D x 160D nylon dobby, 400D nylon plain weave Capacity 19.5-litre, plus 2.5-litre hydration Weight 730g. www.camelbak.com |
 CamelBak Helena 20 $189.99Women’s-specific design, mesh back panel, anatomical S-curved harness and shoulder straps, main compartment with separate essentials pocket, stretch stash pockets, hiking pole attachment, 2.5-litre reservoir included. Fabric 70D x 160D nylon dobby, 400D nylon plain weave Capacity 17.5-litre, plus 2.5-litre hydration Weight 680g. www.camelbak.com |
 Macpac Amp H20 v3 $89.99Moulded foam backpanel, zipped organiser pocket, stretch stash pocket, shoulder strap pockets, reflective detailing, breathable shoulder straps. Fabric 420D nylon Capacity 2-litre Weight 560g. www.macpac.co.nz |