UltrAspire Zygos 5.0 Hydration Pack Review

Last Updated on November 10, 2022 by Heather Hart, ACSM EP, CSCS

As a runner, I’ve been relatively lucky with hydration packs/vests over the last decade. Very early on into my ultrarunning career, I found a brand that worked for me, and stuck with it.

But as my long distance endurance quests became more ridiculous and remote, the race directors putting on said quests began to require that I carry more and more “stuff”.

Suddenly, I found myself in an endurance-athlete-Goldilocks type of situation.

While my normal go-to hydration vest was perfect for running 100 mile races with aid stations every hour or so, it was no longer cutting it for events where I may go an entire 8 hours without the ability to restock food or grab extra layers.

And while I also love the 30L pack that I use for longer adventure races, it was far too big for these 6-8 hour shorter events. (Yes, in this crazy world, 6-8 hours is “shorter”).

I needed a new vest, one that wasn’t too big, or too small, but “just right”. Enter: the UltrAspire Zygos 5.0

UltrAspire Zygos 5.0 Review

Last year I spent FAR too much time researching 30L packs for adventure racing, and finally settled on the UltrAspire Epic XT 2.0. It’s been absolutely amazing, and I’m so happy with the purchase. So when I realized I needed a new hydration vest, I immediately headed to the UltrAspire website.

The Zygos 5.0 looked like the smaller version of the Epic XT. Now, like any good runner in the 21st century would do, I took to some Facebook groups to get the opinions of those who already had the vest. The feedback was overwhelmingly positive, so I put the pack in my virtual shopping cart, and hit the “complete purchase” button.

My husband Geoff didn’t want to be left out, so he bought one too. Leave it to a bunch of endurance athletes to impulse buy hydration vests…

The Zygos 5.0 packs arrived right approximately two days before an 8 hour adventure race. Due to “life” and tapering, we didn’t have the time to give the packs a proper test run. So the first time we used them was during a race.

This, dear readers, is not a recommended strategy. Trying something “new” on race day can often ruin a perfectly good race experience. But luckily for us, that was not the case at all with our UltrAspire Zygos packs, which ultimately made me love this pack even more.

Zygos 5.0 Technical Specs

Let’s start with the basics, so you know what kind of hydration pack we’re dealing with, shall we?

• Total Volume: 14 liters
• Hydration bladder compatible: up to 2 L (70 fl. oz)
  • 2 L bladder is included with the pack
• Weight (empty, including bladder): 16.0 oz (454g)
• Fit:  Unisex
• Available Sizes: Small (30″-36″), Medium (32″-38″) or Large (34″-42″)
• Cost: $184.95 (USD)

Fit:

Fit is arguably the most important factor when it comes to a hydration pack. The fact that it can carry all of the snacks in the world doesn’t matter if it bounces around while you are running, leaving you a chaffed, bloody mess.

Because this pack fits more like a vest than a traditional backpack, and because you are ordering by size (I opted for the size small Zygos 5.0, which is said to fit a chest size of 30″-36″. Geoff opted for a size large. We both felt they ran true to size.) there are less adjustment points than you would find on something like the UltrAspire Epic XT 2.0.

Instead, the Zygos 5.0 uses the Max O2 Form™ sternum strap system, which is composed of stretchy shock cord for unrestricted breathing while maintaining a stable pack.

I won’t lie, I was hesitant at first that these stretchy cords were all I needed to make this pack fit like a glove but…they work.

I was able to run and ride my bike on both paved roads and technical trail, with zero bouncing of the pack.

I credit this to UltrAspire’s ErgoFit, which provides angled shoulder straps (as opposed to flat on many other hydration vests).

Fabric/Materials:

Now, let’s talk about the fabric of the UltrAspire Zygos 5.0. Fit is great, but when you’re wearing a pack for 4 to 12 hours or more, even the best fitting pack can become sweaty and uncomfortable.

Fabric specs from UltrAspires website:

• Lightweight, soft, breathable, but strong, large-holed mesh pulls moisture away from the body to keep skin dry and cool.
• Silicone and PU coated feather-weight nylon fabrics resist water, abrasion and tears.
• Plush feeling micro-fiber polyester edges, soft and non-abrasive against skin and clothing.
• Sweat proof webbing—won’t absorb water or get saturated and heavy.
• Safety stitched bar tack on all stress points.
• Zig zagged stitching over elastic for ultra-durability, increased stretch and rebound.
• The main back compartment has been reinforced at the stress points with XT fabric which contains ripstop fibers

Personally, I have experienced zero chafing from the fabric on the UltrAspire Zygos 5.0, even while wearing a tank top.

(I will, however, update this review once our 90 degree/90% humidity South Carolina swamp weather returns and let you know if that’s still the case.)

With my previous hydration vest, the side/torso panels came up pretty high, which would cause painful rubbing/chafing on the inside of my bicep. But the Zygos 5.0 side panels actually sit lower on my torso, eliminating this problem for me.

Pockets

At first glance, it may seem that the ability to carry water is the main purpose of a hydration pack is to carry hydration. And it is a very important feature, no doubt.

But equally as important is the ability to carry EVERYTHING ELSE you may need during a longer distance endurance event, including (but not limited to): food, your phone, first aid, extra layers, headlamps, extra batteries, bug spray, foot lube…you get the idea.

In short: the longer you go, the more pockets you’re going to need.

And the UltrAspire Zygos 5.0? It has no shortage of pockets. (Watch the video below to see for yourself).

In addition to the main zippered pocket of the pack, the UltrAspire Zygos 5.0 has endless additional pockets.

There are 2 small, zippered pockets on the shoulder straps. These are perfect for holding car keys, an inhaler, money, an I.D., or any other item you want to ensure is safely tucked away.

On the front of the vest, there are a pair of stretch mesh pockets (one of which is zippered and suitable for carrying a large cell phone), a dual 4-way stretch mesh pocket…

…a zippered side pocket

…a magnetically closed side pocket (don’t put your compass in that one)

There’s also a large mesh pocket on the back of the pack, adjust

Performance

While the UltrAspire Zygos 5.0 didn’t help me run faster or better read a map (because boy oh boy did we get lost) during it’s first outing, it did perform incredibly well.

I was able to easily store everything I needed with room to spare, and had zero issues accessing items I needed in various pockets.

Those of you who have read my product reviews before know that the ultimate seal of approval from me for ANY running or adventure gear item is if I forget I’m wearing it. Because whether it’s shoes, a hydration pack, or a sports bra…when I’m racing, I don’t want to think about it.

If I’m constantly noticing that piece of gear, it’s because something is wrong, and it’s distracting me.

The Zygos 5.0? I forgot all about it, until the end of the race when my husband turned to me and said “so how did your new pack work for you?”.

It was great, thank you for asking.

Since then, I have used the Zygos 5.0 on a number of training runs, where I was carrying far less “stuff”. Even when the pack is not filled to capacity, it still it well and performed as expected.

The one complaint I’ve heard – and my husband has experienced as well – is that the larger of the front mesh pockets is not very secure. If you aren’t careful, gels (or whatever you put in that pocket) may bounce out.

It’s my observation that this particular pocket is better suited to hold a water bottle. And as demonstrated above, there’s no shortage of other pockets to put gels/phones/or other items.

UltrAspire Zygos 5.0 Final Thoughts:

Having personally never used any of the previous iterations of the Zygos, I can’t tell you if the 5.0 is an upgrade or “better” than the rest. But I can tell you that I, personally, have fallen in love with it.

I would personally recommend the UltrAspire Zygos 5.0 to any endurance athlete who is looking for a hydration pack that fits like a vest, but has the capability of holding far more gear than other vests on the market.

Questions about my experience with the UltrAspire Zygos 5.0? Leave a comment below!