Nucleus Race Vest

(14 customer reviews)


The Nucleus is a new addition to the vest lineup and features our Ergo X Harness, which is a patented harness system defined by its distinct shape and fit. The Ergo X Harness keeps the weight and pressure points off of the soft tissue areas resulting in better blood flow and cooling. The front pocket is double layered for added capacity. The back compartment is layered with sweat proof fabrics to keep contents safe from moisture and sweat. One side features an on-the-go accessible magnetic pocket for items you wish to keep more secure. The bottom of this compartment has been reinforced with a dual layer of nylon at the stress point for durability. This pack features the UltrAcool Light Mesh for added durability and breathability. The Nucleus utilizes the Max02 Waist closure system which provides an incredible fit with easy adjustment, but also allows for an uninterrupted natural breathing pattern. This vest includes our UltraFlask 550 Hybrid Bottle. One size fits most.

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SKU: UA131BU Category:



• Silicone and PU coated feather-weight nylon fabrics resist water, abrasion and tears.
• Lightweight, soft, breathable, but strong mesh pulls moisture away from the body to keep skin dry and cool.
• 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.
• Ergo X Harness.

Fit:  Unisex
Size:  Universal (Chest Size:  26″-48″)
Color options:  Ice Blue
Hydration Compatible: 1x UltraFlask 550 Hybrid Bottle 
Reservoir Compatible: Not Compatible
Capacity: 305 c.i. (5L)
Weight: 7.2 oz (204g) with bottle, 4.8 oz (136g) without bottle

Additional information

Weight .45 lbs
Dimensions 4 × 3 × 2 in

14 reviews for Nucleus Race Vest

  1. Nolan

    I’m a big fan of minimalist designs. And when I saw the Nucleus combining the capacity of carrying a lot of stuff with it’s double pocket in the rear (the second pocket is a zippered sweat proof pocket for your phone) and a minimalist footprint using the patented Ergo X Harness, I knew I had to have this one. The main pocket in the rear is made with a 4-way stretch mesh. You can easily stuff that pocket with everything you might need. The front of the Nucleus can carry an UltraFlask 550 with ease in its center pocket. While a little unusual for many of the hydration vests out there, it doesn’t take very long to get used to the central location of the bottle. It may even work well with their Soft Flask with Straw and a mag clip. You can carry additional gels and nutrition in the second pocket up front. I particularly like the clever design in the bottle pocket. It has a vertical split in the pocket to make it easier to grab something at the bottom of the pocket should you decide to use a handheld bottle on your epic run and just store nutrition in the center pocket. It also has two additional pockets up front, one that is sippered and another sweat proof pocket using their magnetic closure system. The feel of the vest is great and it just disappears when you’re running. Using their UltrAcool Light Mesh, it is highly breathable in my humid weather on the east coast. And the max O2 closure system allows for a comfortable and snug fit that moves when you breathe. It doesn’t feel constricting at all! I did find that the shock cords could be just a few inches longer. I wear a large t-shirt and find that the cords are pretty snug even when adjusted all the way out. All in all, it’s a great design for those with minimal needs. It’s really comfortable, breathable and cleverly designed. And I’m pretty sure that I can stuff 3-4 giant burritos in the mesh rear pocket. I haven’t actually tried to eat that many burritos, but it’s nice to know that I could carry them along if needed.

  2. Gary T

    I was a little intrigued by the ergo x harness of the reflective neon vest but wanted more storage (phone & water bottle). When I saw that UltrAspire was coming out with the Nucleus vest I knew I had to try it out. I was fortunate that Jodi Hicks (she’s the best) had one available. I am very impressed. It quick became my go to vest. It is very comfortable and feels well balanced (doesn’t shift & stays secure without being overly tight). It doesn’t get hot and is very breathable even with hard efforts ( raced a 10k in over 90 deg weather). All the pockets are very functional and easily accessible even on the move. The waterproof rear pocket is perfect for phones/wallets. The stretch rear pocket will fit a lot of gear and even an extra 550 flask. As I mentioned you can access stuff in both rear pockets on the fly. The front water bottle is very accessible as well as comfortable. It feels well balanced since it is in the center instead of being on one side (if you are carrying one bottle). I have paired it with 550 handheld ( 2 bottles) which I stored in the rear pocket when empty. I paired it with the Fitted Race Belt as well if needing more water. The zippered front pocket fits several gels. The magnetic pocket is perfect for car keys. It is definitely my favorite vest so far. Thank you Bryce and UltrAspire for always coming out with innovative gear !

  3. Faye

    Love the new front bottle design! I am short and arms aren’t long so I love having everything I need right in front of me. Nice phone pocket and front feature bottle holder is great for long runs and hikes where I am frequently grabbing fit my water. Easy in and out access and I love the magnetic pockets for keys and nutrition. I did make the mistake of not wearing a shirt (only sports bra) and it definitely was a bad idea for chaffing. Wear a shirt with this one. Thanks for the innovative design – love it!

  4. Faye

    Love the design with easy front bottle and phone access. I am short with short arms and love that it’s just an easy grab upfront and super easy to put back in place. Love the magnetic pickers for key fob and nutrition. Such an innovative design and UltrAspire nailed it. Pro Tip: don’t wear with only a sports bra or shirtless. You’ll get some chaffing in the front. Otherwise an amazing piece of gear I have worn every week since I bought it June!

  5. Gordon Clark (verified owner)

    Super smart design. Coming from a Nathans with a big bladder, nice to have something sleeker, easier to move with. Pockets are just where they need to be, easy to access w/o having to whip the pack around to shuffle through. Took it out for an easy 10 on the trails at night though (so cooler) and I still soaked through the waterproof phone pocket. (Easy enough fix, ziplock baggies, but still, woulda been nice to have it totally sealed/protected.) So all in all top marks. Only one run in so far. Ripped the shirt off for about 4 miles and didn’t have the scrapes/cuts I would from the Nathans.

  6. Richard (verified owner)

    I am 6’1 and built more like a middle distance runner. I found this pack to be small. It is well made and functional, but too high up for me to use easily.

  7. Robert (verified owner)

    Very comfortable vest to wear. It does not trap additional heat against your body. The design keeps the outsides of your shoulder from feeling loaded down which is really noticeable at the end of a long run. It doesn’t take very long to adjust to the location of the front water bottle and it is easy to access and return to the vest. I am 5’10”, 180 lbs, and I also found the waist closure cords fit pretty snug even when adjusted all the way out. They are probably not much tighter than I would choose to cinch them to keep the vest from shifting around. I have been running in some pretty hot and humid conditions so by the end of the run my clothes are dripping wet. Under these conditions some trace moisture can get inside the sweatproof pockets in the front and back. This is not enough moisture to affect any electronics or your phone. But if you are carrying something that needs to be completely dry, like medications, put them in a plastic bag.

  8. Michael West

    I wore this pack on all the 6 mile and under sections during the Shawnee Hills 100 .
    I really did love it I even carried an Ultraspire bottle in the back area and it rode just fine. I didn’t even know I had it on. Everything worked just like the video showed.

    It was like I was cheating out there

  9. Michael West

    I love this pack it’s like I’m cheating tho. lol
    I ran the Shawnee Hills 100 and used it for the aid stations under 6 miles .
    I also carried one of the Ultraspire bottles in the back also and it rode great. Everything worked just like the video showed.

  10. Ryan P (verified owner)

    I have been looking for some type of vest would carry a hydration bottle in front of my chest where I can swing my hands comfortably while running, I was hesitant about the cost of this vest if I don’t like it. I can say now I’m completely happy with this purchase.

  11. DJ

    BINGO BANGO!!! Man has this vest been clutch since owning it!!!! Some runs I prefer to be stripped down but still have a little something with me and this vest hit the exact mark!!!! Super lite with the ability to even race in this if you needed to!! I love the back pocket centered lower to the back where my phone and extras go if I need to strip my gloves or beanie during a run and do not want to carry them at all!!!! Easily my go to vest for fast runs when I go not want to carry a bottle in my hands. I am 5’11” and around 195 lbs, The vest does fit a little snug but it is not tight. There is no slop or chaffing at all with this vest! Great Job

  12. pamelajeanwhiteley (verified owner)

    Great for ladies! Water bottle sits between the girls rather than directly on them. Easy to reach all the front pockets.

  13. Emma Jurado (verified owner)

    I purchased this vest cause I found all the parts would work for me . But unfortunately having the water bottle in front on my torso was just awkward for me. But ultra aspire always makes epic vests. I’ll find one that will work for me

  14. Ann

    I love the design of this vest and having the bottle in the front. I love not having the bladder holder pocket in back. I didn’t care for the plastic bottle though and used my own soft flask with straw but wish you had something to slide the straw under like the fabric loop for a bladder hose. Love the 2 back pockets and that my phone stays dry. Plus it was super easy to get the phone or a jacket in/out. Not a fan of the zipper and magnetic pockets on the front. The zipper pocket barely fits GU which means it does not fit any other larger gels. My drivers license barely fits. I stuck my gels in the lower pocket where the bottle goes though and that worked good. Would love to see this in your reflective vest material so I could wear at night.

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