Top Hard Enduro Hydration Pack

Hard enduro is slow, but it is not easy. You climb, lift, push and walk the bike, often for hours. At Erzberg, the Red Bull Hare Scramble gives 500 starters 4 hours on one mountain, per the organizer.

What the science says

The American College of Sports Medicine's position stand on exercise and fluid replacement sets the goal of drinking during exercise: to prevent "excessive (>2% body weight loss from water deficit) dehydration and excessive changes in electrolyte balance to avert compromised performance." Because sweat rates and sweat electrolyte content vary widely between people, it recommends customized plans.

The National Athletic Trainers' Association's position statement on fluid replacement adds three points:

• People who drink to thirst, with fluid freely available, replace roughly two-thirds of their sweat losses.
• Sweat rates vary widely. Its own example contrasts 0.4 L/h with more than 2 L/h.
• A body-mass deficit greater than 5% is consistently associated with impaired performance, extreme thirst and headache.

Heat illness

The NHS lists the signs of heat exhaustion, including tiredness, dizziness, headache, cramps, a high temperature and being very thirsty. Its advice: move somewhere cool, remove unnecessary clothing, drink water or an isotonic sports drink, and cool the skin. The person should improve within 30 minutes. Hot skin without sweating, confusion, a seizure or loss of consciousness are signs of heatstroke and need emergency help. See also our first aid basics and the hydration section of our arm pump guide.

A hydration pack is a carrying system, not protection. No EN or ECE rating covers a pack, its harness or its bladder. The certified protection on your back comes from your back protector, covered in the chest protector guide.

So "zero bounce" and "100% bounce-free" are maker claims, not test results. Judge a pack on what you can measure: bladder volume, pack weight, total volume, chest-size range and harness adjustment.

Keep hard objects out of the pocket over your spine, because the pack sits directly on your back and hard enduro falls land you on rocks and logs. A soft tool roll spreads a load. A loose wrench does not.

Both ACSM and NATA say to base your intake on your own sweat rate. NATA's method:

1. Weigh yourself before and after the ride, in kilograms.
2. Sweat loss (L) = weight before − weight after + fluid drunk (L) − urine (L).
3. Sweat rate (L/h) = sweat loss ÷ hours ridden.

NATA recommends repeating this in realistic conditions, wearing your sport's clothing and equipment. For you, that means full kit on a real hard enduro loop.

A worked example

These numbers are illustrative, not data. An 80 kg rider's 2% line is 1.6 kg. If that rider sweats 1.0 L/h, a 4-hour race costs 4.0 L. A 3.0 L bladder leaves a gap even if every drop gets drunk, and drinking to thirst alone replaces only about two-thirds of losses, per NATA.

Our view: for most hard enduro days, carry a 3 L bladder and plan where you will refill. Keep a 1.5 L race pack for short loops or races with pit support. That advice comes from three things: the worked example above, where a 4-hour race at 1.0 L/h costs 4.0 L; the 4-hour Erzberg format; and NATA's example sweat rates of 0.4 L/h and more than 2 L/h.

Water or sports drink?

ACSM says drinks with electrolytes and carbohydrates can give benefits over water alone under certain circumstances. NATA warns about the opposite risk: overdrinking can cause exercise-associated hyponatremia, which it reports in 10% to 20% of distance athletes after events. Drink to a plan, not to the bottom of the bladder.

Water weighs 1 kg per liter. On any pack, the water is the heaviest thing you carry. Here is what the makers list:

Pick the bladder size first and the pack second. The table above shows why. The listed pack weights span 310 g to 1,130 g, and USWE quotes its weights without the bladder. The difference between a full 1.5 L and a full 3.0 L bladder is 1.5 kg of water alone.

On a log or a rock step your body moves hard and fast. A pack that lags behind pulls on your shoulders and shifts your balance, which makes good body positioning harder.

USWE's NDM harness

USWE builds its moto packs around its No Dancing Monkey (NDM) harness. USWE says the harness is patented, uses 4-point suspension with elastic chest straps that expand as you breathe, and makes the packs "100% bounce free". These are the maker's claims. USWE's setup steps:

1. Adjust the horizontal chest straps to a comfortable length. Two D-rings switch between a larger and smaller size.
2. Adjust the vertical shoulder straps so the center buckle sits around the height of your solar plexus.

USWE lists a chest range of 84 cm to 110 cm for both of its packs here. Measure your chest over your armor.

CamelBak's approach

The M.U.L.E. Pro 14 uses a mesh harness, a sternum strap and a hip belt that CamelBak says adds stability. The Chase Adventure 8 vest uses dual sternum straps, and CamelBak calls its fit "stable, bounce-free". CamelBak sells both as bike products.

Our view: test stability standing on the pegs, not standing in the shop. The logic is simple: hard enduro is ridden mostly standing, and a pack that sits still when you are upright can shift when you lean forward.

Your pack shares your torso with a chest protector and, for many riders, a neck brace.

Over armor

Check the specific model, not the brand:

• USWE says the OUTLANDER Moto 2L's elastic harness "stretches to fit over moto gear and body armor".
• USWE says the standard Moto Hydro 8L "is designed for a close fit without body armor", and points chest-protector wearers to its Adventure Fit version with extended straps.
• CamelBak lists both of its packs here as compatible with its own Impact Protector panel.

With a neck brace

Try brace, chest protector and pack together, in your riding stance, before you ride. Check that the top of the pack does not push on the brace and the straps do not lift it. We say this because all three bear on your shoulders and upper back at once, so a shift in one moves the others. Brace fit is covered in the neck brace guide.

Routing the hose

USWE says the OUTLANDER Moto 2L's fixed tube coupling keeps the hose secure, and that you can clip the hose to the harness so it does not flap. We'd route it so you can grab the bite valve fast, clear of the brace and goggle strap, because in hard enduro you mostly drink in short stops, such as while waiting at a jammed climb.

1. Choose the bladder first. Use your sweat rate and your longest stretch between refills. For most hard enduro days that points to 3 L.
2. Choose the smallest pack that carries it and your essentials. Space you do not need tempts you to fill it. The bike setup guide helps decide what can live on the bike.
3. Prioritize a harness that clamps the pack to your torso, such as a four-point design. Stability matters more than storage, because on a log or a rock step your body moves hard and fast, and a pack that lags behind shifts your balance.
4. Check the fit over your armor. Use the maker's chest range and armor guidance.
5. Route the hose clear of your chest protector and neck brace.
6. Pack tools and food for the route length and the heat. Keep hard items off your spine.
7. Try the full kit at home. Stand on the pegs and move.

The pack

Both makers say no washing machine. CamelBak's care guide says it can twist or tear straps and fixtures, wear away the weatherproof coating, and void the warranty. CamelBak says to soak a dirty pack in water with mild soap, rinse it thoroughly with cool water and hang it to dry. USWE says to empty the pack after every ride, brush soiled areas with soapy water, hand wash only (a machine or dryer damages the PU coating), keep zippers clean, and store it closed in a dry, ventilated place.

The bladder

USWE says to rinse its Elite bladder with warm water after each ride and let it air dry completely, opening propped open, to prevent mold. For a deeper clean, turn it inside out like a sock, put it in the dishwasher or wash it with mild soap, and dry it while reversed. CamelBak's reservoir wash: fill it half full of warm water and mild soap, shake, hold it so the bite valve is below the reservoir, pinch the valve so the solution runs through the tube, then rinse, drain and air dry so no moisture is trapped inside.

Before each season

CamelBak's checklist: inspect the reservoir, run clean water through it, tug both ends of the tube (if it comes off too easily, trim an inch off and refit it), then fill, cap and squeeze it to check for leaks. If the cap leaks, CamelBak names two likely causes: grit in the threads, especially in sand, or a twisted O-ring. Check the threads after every muddy ride or water crossing. That follows from CamelBak's note about grit, and from the silt a hard enduro day leaves on your kit.

• Drinking only when thirsty on a long day. NATA reports that drinking to thirst replaces roughly two-thirds of sweat losses. Over four hours, the gap grows.
• Drinking plain water by the liter with no plan. NATA links overdrinking to exercise-associated hyponatremia.
• Riding with loose straps. Set the harness up the way the maker describes. USWE's own setup steps above show how.
• Buying the biggest pack. The water is the weight. A larger pack mostly adds room for more.
• Leaving the bladder wet in the pack. Both makers say to dry it fully. USWE names mold as the reason.
• Never trying the pack with armor and a brace. USWE's own armor guidance differs by model.

For the rest of your kit, see the gear overview, and build the fitness for long days with endurance training.