How to Choose a Hydration Pack for Mountain Biking

When choosing a hydration pack you need to consider many different factors. For instance, how much water you want to carry, how much other storage space you’ll need, and how you want the pack to fit. I’m going to walk you through some of the main points you’ll want to consider, and offer a few suggestions to help you decide on a product that’s right for you–whether it’s your first or fifteenth hydration pack purchase.

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By Jeff Barber

An Intro to Hydration Packs

What exactly is a hydration pack? It’s basically any backpack that is designed to hold a reservoir full of water (sometimes called a bladder), which connects to a hose that is easily accessible while riding (or participating in whatever activity you choose). There is generally a separate compartment specially built in for holding the water to keep it from moving around or creating uncomfortable pressure points on your back as you’re wearing the pack.

Some of these packs don’t have space for much more than a water reservoir, while many others have plenty of room for items such as tools, spare tubes, extra clothes, a camera, food, and even camping gear.

There are many different options when it comes to storage capacity, fit, and special features, so I’m going to break down some of these different variables to hopefully help you figure out what might work best for your needs.

Water Capacity

The first thing you’ll want to figure out is how much water you need and want to carry. Keep in mind that you don’t always have to fill up the bladder completely, so it might behoove you to buy a pack with a water capacity that is slightly larger than what you think you’ll need for everyday rides, but what you might want for the occasional long ride.

Of course, the tradeoff is size and weight–even with an empty reservoir, a pack with a larger capacity will carry a larger footprint and weigh more than a pack with a smaller capacity.

Typically, bladders are one of three sizes: 50oz (1.5L), 70oz (2L), or 100oz (3L), though the smallest size isn’t very common anymore. Most hydration packs have a dedicated area for the bladder, which is usually designed around a particular bladder size and advertised as such, but also may be able to accommodate different sizes. For instance, sometimes it is possible to make a larger-than-intended reservoir work, but it’s not a good idea to count on that when buying a pack.

Bladders come in a variety of shapes and sizes.

Bladders come in a variety of shapes and sizes.

This dedicated reservoir area is usually separated from the rest of the pack, and a padded section between your back and the reservoir adds comfort and minimizes the sensation of a bulge of liquid against your spine while pedaling.

So, how do you decide how much water storage space you need? I find that more space is better than less, because I like to be prepared for long rides and I tend to drink a lot, especially in the warmer months. I also ride small frames, which usually only have one bottle cage mount, so I have no qualms about carrying a slightly bigger pack. As a result, I personally use a 100oz water capacity. But if you rarely or never ride for more than a couple hours, find that you just don’t drink very much, or have other water storage options (bottle cages, etc.) and will only be using the hydration pack to supplement that water, you should be able to get away with a smaller pack.

A Word About Reservoirs

Not all hydration pack reservoirs are the same. Aside from being different sizes, they also vary in their rigidity, shape, and integrated features. Some reservoirs are soft and pliable, while others are more rigid and hold their shape. Softer reservoirs tend to sag inside the hydration pack, unless there are specific hooks or holders to keep them in place, which most packs will have if they are designed for that type of reservoir. Since some packs are sold without a bladder, just made sure your pack and bladder are compatible so that you aren’t dealing with unnecessary annoyances.

platypus soft reservoir photo by maureen

This Platypus reservoir is soft, but attaches to the pack via clips to keep it in place and eliminate sag. Photo: Maureen Gaffney.

Bladders also have different fill and closing mechanisms. Some have a circular screw-on lid (like the Osprey pictured below), while others have a Ziplock-style or roll-top closure. I’m not sure that one style is better than another; it all depends on your personal preference. I will say that a large opening on one end (see the Hydrapak below) makes cleaning and drying out your reservoir much easier.

osprey bladder photo corey maddocks

This Osprey reservoir is on the stiffer end of the spectrum. Photo: Corey Maddocks.

This Hydrapak reservoir is easy to clean due to its large opening on one side. Photo: Jeff Barber.

This Hydrapak reservoir is easy to clean due to its large opening on one end. Photo: Jeff Barber.


Though it’s called a “hydration pack,” water capacity isn’t the only important factor to consider when choosing a bag to take mountain biking. Storage space is highly variable, and ranges from barely enough room for a phone and keys to a full-size backpack that can hold everything from camping gear to camera equipment.

A minimal pack might be the ticket if you have ample frame storage on your bike, and you want to carry plenty of water on your back and leave frame bags for other supplies. If you have a small frame and can’t fit a lot on it, you’ll probably need a larger pack to compensate. If you enjoy photography more than the average person and want to take a large camera and multiple lenses along with you while riding, you may want to look into a backpack specifically designed to carry photography equipment.

Most of us fall somewhere in the middle, and want a pack that will hold plenty of water, as well as a few other items, such as tools, food, and an extra layer or rain jacket. The majority of hydration packs on the market are designed with these exact needs in mind.

Many hydration packs include small pockets for organization, and some come with a tool roll. Photos: Corey Maddocks

Many hydration packs include small pockets for organization, and some come with a tool roll. Photos: Corey Maddocks


The fit of your pack is not something to be taken lightly. After all, the last thing you need is to be uncomfortable as you’re barreling down sketchy descents, slogging up a killer climb, or just trying to enjoy a peaceful day on some singletrack.

There are a couple different styles of hydration pack on the market. The majority of packs are similar to a typical backpack in that they are attached to you mainly via two shoulder straps. Most of the time, they’ll also have a chest strap and hip belt to customize the fit and keep the bag from bouncing around as you’re in motion.

A chest strap and hip belt help keep hydration packs secure while riding.

A chest strap and hip belt help keep hydration packs secure while riding.

Some hip belts are padded and include small pockets for easy access to essentials. I usually keep my phone/camera in one of my hip pockets and a multi-tool and energy chews in the other. Other hip belts, typically on smaller packs, consist of just a thin strap that goes around your waist to keep the bag in place.

A slightly different style of hydration pack is the “lowrider” or “lumbar reservoir,” both of which coincidentally have the initials “LR” and mean the same thing–the weight of the pack, the water, and other gear is kept on the lower back and hips, relieving the mid-back from any burden. This is a great option for people with back issues that can’t wear a regular pack, or people who just prefer this type of weight distribution. Some of these packs are basically a glorified fanny pack, while others still have shoulder straps (see the recommendations section on page 2 for examples).

What about women’s-specific packs?

The Osprey Verve women's pack. Photo: Julie Hughey.

The Osprey Verve women’s pack. Photo: Julie Hughey.

Women’s-specific hydration packs tend to be shorter, and sport ergonomically-designed straps to accommodate a different body shape, especially in the chest area. That being said, just because you’re a female doesn’t automatically mean you need a women’s-specific pack. Just like with bikes, “women’s-specific” means a certain set of variables will be generally different than a “unisex” model, and those characteristics may or may not work for individual women.

Some women have long torsos, and like the fit of a unisex pack better. That being said, there may be some men out there who find that a women’s pack fits better, and there’s nothing wrong with that. If you’re unsure, it might be a good idea to head over to your local bike shop and try a few on before you buy.

Other Factors

Waterproofness: Some bags are more waterproof than others. Some hydration packs also include a waterproof cover that can be pulled out in case of rain. This might be an important consideration if you ride in wet conditions on a regular basis, or if you’re carrying sensitive equipment (like a camera).

Availability of Parts: If you travel to other countries a lot for bike adventures, it is worth looking into the vailability of parts, such as bite valves, for certain brands. CamelBak is probably still the most widespread hydration pack brand across the world, but other companies, such as Osprey and Dakine, are quickly growing in popularity.

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