UltrAspire Alpha 5.0 Race Vest Review

An in-depth review of the UltrAspire Alpha 5.0 Race Vest.

Staring at my pile of hydration packs for running often makes me feel a little like Goldilocks. Some are too small, others are too big, too heavy, or too bouncy. After months of hydration pack testing, the UltrAspire Alpha 5.0 Race Vest ($125) has emerged as a pack that more often than not is just right. Light enough for quick jaunts with expandable storage for longer days, this pack is a versatile option that fits the bill for all but the longest of trail days.

This pack is full of thoughtful features that enhance storage capacity and improve the fit without feeling too heavy or overbuilt. UltrAspire’s ErgoFit harness design and UltrAcool system balance the gear load and help dissipate heat, maintaining comfort in a variety of conditions. Its six-liter storage capacity is separated into 10 pockets to keep gear organized, nine of which are accessible while wearing the pack for easy access on the fly. The pack comes in unisex small, medium, and large sizes, which are advertised to fit chest sizes from 31 to 42 inches. The advertised weight of the pack is 9.6 ounces.

Whether you are just dipping your toes into the trail running scene or are a seasoned ultrarunner looking for a race-ready pack, this one will have you covered.

By the way, the iRunFar gear testing team enjoys this pack so much that we’ve named it the Best Overall Medium-Capacity Hydration Pack in our Best Hydration Packs for Running guide.

A front view of the UltrAspire Alpha 5.0 Race Vest. All photos: iRunFar/Carly Eisley

The foundation of all of UltrAspire’s running vests, including the UltrAspire Alpha 5.0 Race Vest, is their ErgoFit harness system that is designed to keep the pack balanced without inhibiting natural running movement. This fit features longer, S-curved shoulder straps that keep pressure off the back of your neck and prevent restriction around the arms and chest for better range of motion and arm swing. This also balances the gear load, keeping weight evenly distributed, whether you’re carrying the bare essentials or a full load.

The pack is designed to keep the weight lower on the body and closer to your center of gravity to prevent bouncing and minimize wasted energy. This means that the rear of the pack is a little longer than those made by other manufacturers. I have a shorter torso, so initially, this felt very noticeable to me as the pack sat further down on my back than most of the others I’ve tried. I quickly got used to the longer fit and appreciate the stability this provides.

The pack comes in three unisex sizes, using a single measurement under the armpits around the largest point of the chest. The sizing will fit chests ranging from 31 to 42 inches.

At first glance, this pack felt big — I have a 34-inch chest, which is in the middle of the range for a size small pack, and I felt like I had to cinch it down all the way to get a secure fit. After some time wearing it, I came to realize that unlike many other packs I’ve tried in the past, this one does not need to be super tight in order to stay stable and not bounce.

The only adjustment points are the two front elastic shock cords, which UltrAspire calls their MaxO2 Sternum. This is an appropriate moniker, as I felt like I could definitely breathe easily with this pack on! The length of the back of the size small pack is 15.5 inches, which lands right around the middle of my lower back, right in the waistband area.

The vest is essentially made from two layers — a mesh inner lining that sits against the body, and stretchy outer material that forms the pockets. UltrAspire’s UltrAcool Mesh liner is made of polyester in a fine honeycomb pattern that wicks away sweat and breathes well without absorbing any moisture. The mesh itself feels a little rough to the touch, but I never wore it without a shirt or tank top underneath, so I had no problems with discomfort. There is a soft layer of material sewn around all of the edges where they contact the body to prevent chafing.

The exterior of the pack is made of a durable, breathable, and stretchy Powernet mesh that expands just enough to comfortably fit gear without sagging when empty. There is a polyurethane-coated nylon panel inside the rear passage pocket and a small envelope pocket on the right shoulder strap of the same material to keep items dry. The pack is available in one deep teal-like blue colorway to keep things nice and simple.

A view of the phone pocket of the UltrAspire Alpha 5.0 Race Vest.

As mentioned above, the UltrAspire Alpha 5.0 Race Vest has a total of 10 pockets distributed between the front and back. Nine of those are accessible with the pack on, making it easy to organize items for easy access during a race, when you don’t want to lose time removing the pack or fiddling with hard-to-reach storage.

The front of the pack features two large cinch-closure pockets, one on each chest strap. These are positioned below the chest and can each fit a 500-milliliter soft flask or UltrAspire’s hybrid bottle. The UltraFlask 550 Hybrid Bottle is a pliable plastic bottle that has a more elongated, curved shape and that sits more flush against the chest as compared with a regular round bottle. I found these bottles to fit snugly and work very well in this vest, bouncing less than a regular soft flask.

If you aren’t carrying hydration in the front pockets, there is ample room for gels, a small pair of gloves, or a buff. These are also my preferred phone storage pockets if I’m not using them for hydration. A bonus feature of the front pockets is a small opening at the chest cord that allows the loose end of the shock cord to be tucked away so that it doesn’t flop around while running.

Above the main pocket on the right chest strap is a small magnet-closure nylon pocket that is water-resistant and a good place to store something like salt tabs. This pocket is pretty small and I personally don’t use salt tabs, so I didn’t often put anything in there.

Perhaps the most unique front pocket is the phone pocket on the upper left of the front chest strap. This is a stretchy sleeve that the phone slides into vertically with an elastic cinch cord to keep it stable. I’ll admit when I first saw this pocket, I thought there was absolutely no way it would be comfortable and keep the phone stable while moving. It turns out I was wrong! It is surprisingly stable and easy to use, and I ultimately forgot my phone was there while running.

The one thing that is noticeably absent from the front is a whistle. I was very surprised UltrAspire did not include this given their otherwise impressive attention to detail throughout the pack.

Two identical zipper pockets sit on the sides of the pack under the arms. These are secure spots for small items you need readily available, but also really don’t want to lose. A small stuff pocket lies beneath these for an added stash space. I often use one of the side zip pockets for my key, and the stretchy sleeve beneath it is perfect to stash away a buff. However, the side zip compartments are too small for my iPhone.

The largest pocket is the rear compartment that spans the length of the pack. The main compartment is large enough to stuff food, a first-aid kit, and your just-in-case extra layers. A sleeve inside this pocket holds the included two-liter hydration bladder and also has a removable Mylar sleeve that provides insulation for the hydration bladder. The sleeve, which snaps in and out, can be easily removed for better ventilation. This main pocket does have a fair amount of stretch but doesn’t hold much extra gear when the hydration bladder is full.

Overlying the outside of the large rear compartment is a bungee cinch cord to quickly strap items like a jacket or vest when you are taking layers on and off in variable temperatures.

A pass-through pocket sits across the lower back of the pack and is easy to access from either side with the pack on. This has a nylon component to improve water resistance and a magnet closure to keep things more secure. This is my preferred pocket to stash a lightweight jacket, especially if I am taking it on and off frequently.

Two bungee trekking pole attachments sit along the low back of the pack. They have a little bit of bounce, but on shorter runs, I didn’t notice my poles back there once I got going. They are not easy to access while moving, though, and most people will have to remove the pack to get to the poles. There is no alternative front pole storage, something to keep in mind if that is important to you.

As mentioned above, this race vest can carry up to three liters of fluids between the two front bottle pockets and the two-liter hydration bladder sleeve in the back. I found that I preferred to keep at least one of the larger front pockets open to use for gear, as there is limited front storage if both pockets are carrying hydration.

A back view of the UltrAspire Alpha 5.0 Race Vest jacket stuff pocket.

The UltrAspire Alpha 5.0 Race Vest was a pleasant surprise for me. Admittedly, my initial thoughts when trying it on were that it was going to be way too big and not work out well at all. Thankfully, I couldn’t have been more wrong. The pack rides well both loaded with hydration and gear as well as minimally stuffed.

The material is durable but on the heavier side, which makes this pack feel a little bulky. It definitely felt warm and less breathable in hot weather as compared with some other packs out there.

One of UltrAspire’s strengths is their attention to small details in their pack design and function, and this running hydration pack is no exception. The pocket placement and closures all have specific uses that make them very functional. Overall, this pack is a great option for supported races or few-hour training runs where you will need a good amount of fluids and gear but don’t need to carry a full day’s worth of stuff.

Be sure to click over to our Best Hydration Packs for Running guide to see why we named it our Best Overall Medium-Capacity Hydration Pack and how it compares to other top hydration packs for running.

[Editor’s Note: If you’re affiliated (i.e., an employee, ambassador, etc.) with a brand, please share your relation in each of your comments on this article. Thanks!]

A back view of the Ultraspire Alpha 5.0 Race Vest.

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