Mountain Hardwear Fluid Race Vest

Are you a bottle or a pack person? Check out any trail race and you’re bound to see runners neatly divided into these two categories, and as hydration packs become more lightweight and innovative, bottle users can no longer use the excuse that packs are bulky and hindersome. The dawn of the race vest has brought lightweight, barely noticeable, pack options with a variety of storage mechanisms. Seen with increasing regularity on the trails is the, gasp, pack and bottle combo! While other hydration packs have received more press and big marketing pushes, the Mountain Hardwear Fluid Race Vest ($60) has snuck mostly under the radar. Not to be confused with the more recently released Fluid Race Pack which has additional storage, the Fluid Race Vest is a lightweight, no frills, affordable pack, which at first glance is even underwhelming.

Over the past five months I’ve had the opportunity to take this pack on outings between two and seven hours, always managing to cram more than enough unnecessary gear into its surprisingly expansive compartments.

Mountain Hardwear Fluid Race Vest - front

The front of the Mountain Hardwear Fluid Race Vest.

Shape, Construction, Fit

The Fluid Race Vest comes in two sizes small/ medium and medium/ large. The S/M size is meant to fit runners with chest-width measurements between 16-19 inches and the M/L size 18.5-22 inches (measuring straight across the chest). I received the S/M size for testing, and with an 18-inch torso my first impression was that this vest felt a little snug. I was underestimating the elasticity of the straps on the front of the vest as well as its ability to hug and conform to the torso. The fit of the Race Vest feels higher on the ribs than other hydration vests I’d worn and it took some getting used to. The function of this fit became immediately apparent while out on the trail as I experienced absolutely zero bounce with the vest fully loaded. More on that later.

Two very simple nylon cross straps equipped with elastic bands help dial in the fit of the Fluid Race Vest. Placement of these straps is adjustable on both sides, which with a bit of playing around, could net an even more dialed in fit. I feel that the stock positioning of these straps works great for me and I didn’t need too much adjusting.

Almost ninety percent of the Fluid Race Vest is made up of very lightweight breathable mesh which has now become the industry standard for most vests. However, Mountain Hardwear kept weight down by using an even thinner stretch mesh to create pockets, and this may be the stretchiest mesh I’ve seen. What first seems like very little cargo capacity becomes exponentially larger when stretched a bit, and the mesh never seems to lose elasticity even after a machine wash.

Cargo Storage

The back compartment of the vest features an external bungee that I’ve used to hold a lightweight shell, gloves, and a hat. This main compartment is simple and can hold a surprisingly large amount of gear. In inclement weather I’ve stashed a rain shell, headlamp, gloves, hat, and extra food in this back pouch without experiencing discomfort, and although there is no back padding, I’ve even carried an extra 20-ounce water bottle without any discomfort. This large compartment can also be used to carry a bladder, and guide straps are present on the front of the vest to keep the drinking hose from bouncing all over. While I’ve used larger bladders in this pack, it seems to perform best with a 1.5-liter/50-ounce bladder that produced the best overall comfort-to-carrying capacity ratio.

The front right side of the Fluid Race Vest has a large bungeed pocket down low that can be used to carry a bottle, even a 20-ounce bottle, or a variety of other gear. Because the pocket angles down, carrying a bottle does take a little getting used to, but I found myself leaning more and more to putting a soft flask in this compartment which seemed to take up less room and it also alleviated the annoying sloshing sound of carrying a bottle. Above this compartment is a small zippered pocket which can be used to carry pills, a few gels, or other small items (a credit card does not fit into this pocket).

The front left side of the vest features a large zippered compartment on the bottom that accommodated a smartphone or numerous gels. (I think I crammed eight in there once!) The pocket above this is a smaller with a velcro flap which also works well to store electrolytes, keys, and small items. No pockets on the vest are waterproof, which was my only disappointment on this vest.

Mountain Hardwear Fluid Race Vest - rear

Mountain Hardwear Fluid Race Vest from behind.

Overall Performance

With a price tag of $60 and an unloaded weight of 5.6 ounces, the Fluid Race Vest is the lightest and cheapest major-manufacturer race vest on the market. Given these stats I expected absolute minimalism, yet what I found was an incredibly versatile way to store the essentials which feels like part of my body while I’m running. When loaded with only gels, pills, and clothing, I experienced absolutely no bouncing, and with a 50-ounce bladder bouncing was very minimal. Most of the time I’ve worn the Fluid Race Vest, which is almost every long run in the past four months, I’ve forgotten that I had it on.

If you’re like me and belts feel uncomfortable to store your food or gear, a minimal pack like the Race Vest is the way to go. With a myriad of options for carrying a bladder, storing a bottle, or using soft flasks you can customize this vest to meet the needs of almost any distance.

[Note: The Mountain Hardwear Fluid Race Vest is normally available in the iRunFar Store.]

Tom Caughlan

is iRunFar's Minimalist Gear Editor. Tom’s passion for trail running and specialty running retail experience shine through in all of his highly technical reviews, which do range outside minimalist shoes.

There are 39 comments

  1. brandon

    This pack strikes me as a blend of the AK pack from Ultimate Direction and the Spry from Ultraspire. I've been messing around with carrying bottle(s) versus bladder versus waist pack. I go back and forth but the combo that seems to work best for me is the older version of the Spry and carrying one or two Ultimate Direction bottles, one 20oz and the other 26oz. The pocket on the Spry is just right for holding the 20oz bottle but I normally use it for a quick stash of the bottle then it goes back into my hand. It's cool to see the variety of pack options coming out and the variety of combinations other runners come up with. And everything keeps getting light and lighter. Now all we need is a tech shirt with integrated pockets in lieu of a vest and then we'd all be oh so minimal.

    1. Ben Clark

      I like the idea of the tech shirt but I'm afraid that with it would chafe without a hip belt to secure it and then you'd be right back to wearing a hip belt that happens to be a shirt-that stinks b/c you wear it all the time ;-)

      1. brandon

        I wouldn't necessarily mind the stink, but my wife would. My joke to her, upon returning home from a long run, is that "hey, I work hard to smell this bad". She's starting to find the humor in that – she's a keeper.

    1. Kim Neill

      Nathan Intensity has 2 zipper compartments on back: one for stuff, food, clothes; the other for a hydration bladder and a few items with it. Also has more adjustability with adjustable side straps as well as the front/chest strap.

  2. Amy

    This is my go-to pack for any race where you don't have to carry a ton of required gear (à la UTMB). I absolutely love it. I always use it with a bladder, usually 1.5L. I've never found a pack that fits me so well, doesn't bounce, is super light, yet still holds a lot of stuff (admittedly, I'm sponsored by MHW, but I'm also a pain in the butt, and don't wear something unless I love it–this, I love). I've also had a love-hate relationship with many of my packs in the past for one reason or another (placement of shoulder/sternum straps, bouncing, accessibility), and don't like to carry handhelds.

      1. Amy

        They're pretty different. There are no adjustable side straps with the MHW and all the adjustment is done with the front straps, which you can move around (in the photo you'll notice 6 slots) to fit. It's all mesh pockets, so the compartments aren't bulky like in the Nathan (I have a Nathan that's several years old, but looks similar). This reminds me more of the Nathan Krissy (I think it was called that back in the day) vest, in terms of weight and design, but holds more (including a bladder) without issue.

  3. Digga

    All this still does down to whether or not you are a hand held bottle guy or a pack guy.

    Packs/ vests are just too warm for me. It has to cold out like below 50 for me to consider anything over my shoulders.

    With races there is aide every 4 to 8 miles therefore I do need to carry anything more than 20 oz and a gel or two.

    Anyway, thanks for write up……

  4. KenZ

    I've been using one on and off since November. It's part of the quiver, as it has its niche, and a good one.

    +++PROS are for a pack it's super light weight, doesn't bounce, and carries a reasonable amount of essentials. I do mean essentials only. And I think it looks decent, not that this makes me any faster.

    —CONS a) agree with some that it would be nice to have a LITTLE adjustment on the sides so that broad shoulders would work better. b) I find the location of the front pockets a little low; if they moved all the pockets up the shoulder straps by even an inch, they'd be a bit easier to work with. c) In the back, you have the bungee for securing clothing or IN THEORY tightening down on your water bladder. I'd like to see a second additional non-bungee/unstretchable securing mechanism that could be pulled from one of the sides. This would help cinch down the bladder better as you empty it on the move. Note that no pack I know of short of possibly the Nathan 020 with its cross-back side straps has this. I will be adding it. d) like any pack, it adds to your heat load which can affect performance as pointed out above by Digga.

    Overall, I consider it an essential one of my packs for use in its niche.

    Thusly, my race quiver ends up being:

    **Races up to 50M with aid stations ~5 miles apart: Amphipod 20oz bottle tucked in the back of my shorts. Advantage: totally minimalist, no heat load on body.

    **Races up to 100M with aid stations in the 8-10 miles spread: Ultraspire Impulse, but with Amphipod bottles (which don't have the large drawbacks of the Ultraspire bottles). Advantage: minimal heat build up, small equipment carrying capacity.

    **100M race starting at the night sections if cold necessitates more gear than Ultraspire Impulse can easily handle (pack picked up from drop bag): MHW Fluid Race Vest. Advantage: Carries all one needs for US-based races in a super light weight pack. It's also my go-to pack for 2+ hour training runs when I want to carry some options.

    **100M races overseas: Nathan HPL 020. You know, because they require you to carry the kitchen sink. Advantage: well built, lightweight for the storage capacity, tons of storage for the weight.

    1. Skylar

      Thanks for sharing your various configurations. Perhaps a silly question, but when you tuck the Amphipod bottle into your shorts… is that without its hand strap, I presume?

  5. tam

    I've used a Camelbak for years and am considering getting a lighter pack that doesn't cause so much chaffing on my back. This vest looks like a good option.

    Question: The Camelbak came with a bladder. With the MHW vest, do you buy a bladder and insert it?

  6. Ultrawolf

    Can anyone compare the MHW with the Ultimate Direction AK vest ?

    The rear department is about the same size I suppose ? Any other pro/cons apart from the prize ?

    Thanks !


    1. Nikos

      I would like to see the same comparison. Maybe with the Nathan Minimist as well. It looks very similar to. I wonder if they are enough to carry required gear(for races like UTMB)if you don 't use the bladder. I prefer light weight in my back and a hand bottle for water.

  7. sean

    I used to be a bottle guy, but developed shoulder soreness during long races from carrying the hand helds. I switched to the AK race vest with Amphipods. With hands free, I no longer have the soreness and my shorts don't get weighted down with gels/pills. Will recommend this to friends who are on the fence about race vests.

  8. Paul

    I love the Mtn Hardwear gear. I use the Fluid Race Pack, not the vest because I use it for my longer training runs and need larger bladder space. Front vest is pretty much the same except for the bungie pocket is not large enough for water bottle. I love it. Mtn hardwear keeps coming out with better and better stuff designed for running

  9. KenZ

    Yeah, without any handstrap (I really don't like handhelds, but that's a different discussion). Basically, I'm using the 20oz Amphipod like a larger version of this: without the tab. The only reason I don't use the simplehyudration variant is at 13oz it's just not nearly large enough, and I don't want to shove two of them in the shorts for most runs.

    To be fair, to get it to work because it doesn't have the tab like the simplehydration, I have to tighten my shorts drawstring _very_ tight to keep it from slipping down. This means I pee (here comes TMI) by pulling the shorts leg to the side.

    At White River 50, I did tuck TWO 20oz Amphipods in the back of my shorts, and that actually worked well. However, I've found that with two they sit and rub a bit on that ridge down your back on either side of the spine, so around 40 miles some lower back chaffing occurred.

    What I would really like is a 22-24 oz variant of the simplehydration bottle. But it doesn't exist.

    1. Paul

      I think sometimes it's just how they fit on you. I've never had any issues with chafe with any type of pack I have ever worn. I think the count is 5 different packs now. I try to make sure pack is snug and secure so I don't get much bounce, and I never want the shoulder straps riding up my neck.

      1. KenZ

        I agree. I've never had a problem EXCEPT if I go shirtless or if the pack sometimes "sucks" the shirt up and then I have lower pack on skin. Have to tuck the shirt into the shorts then.

  10. geoff

    To me the lack of adjustable side straps is one of the best things about this vest. the way the mesh comes around your side is much more comfortable than adjustable straps tend to be in this area and this design makes the vest ride more comfortable than any similar packs i've tried. at first i thought i'd miss the extra adjustability, but after using it for awhile i began to realize that it was really nice to only need to make one quick adjustment rather than 3. most comfortable pack i've ever run in… by far!

  11. Tris

    Any idea where this can be sourced in Europe? Looking at the Mountain Hardware EU site and the usual "other" online stores I can't find it. Could be that it hasn't yet been launched on this side of the pond?

  12. snoxu

    Shot them an email. In the EU it's a no go:

    Unfortunately, the item you are looking for was not produced and is not available for the European market, but only for he U.S. one.

    You can buy products seen on the U.S. online web side, but therefore you need to provide a delivery address in the States.

    We invite you to have a look at our various products on our European website.

    If you find a product on the website and are looking for a store where you can find it, we invite you to use our store locator:

    I’m afraid, however that we cannot be of better assistance to find the item you’re looking for, but we hope that you will find an appropriate replacement.

  13. Chad

    I think the fitting section is incorrect. Like most hiking packs you measure from the C7 neck vertebrae down to the crest of the hip bone.
    It's not a chest width measurement.

  14. Kix

    Needing a little help with hydration pack issues please. I just ran part of the Canadian Death Race and found that I am not a camel! I was using a 3L pack with water in it and then a run belt with four little bottles with electrolytes. I was seriously close to depleting all of my fluids – and there was no guarantee that the aid station on top of mountain would have water. Any suggestions for a system that could give me a little more would be appreciated. Also, need to carry a warmer jacket as I had a thin one packed but, it was not enough to prevent hypothermia. I don't want to be carrying everything but the kitchen sink but, running in the mountains does pose some logistical issues. So, the pack would also have to accommodate a few other things than fluid. Thank you for any responses.


  15. Christina Brooks

    I also have one for sale, I bought for a race I had to back out of becuase of shin splints…..didnt even take the tags off. I will shoot you all an email if anyone is still interested.

  16. KenZ

    Answer: Not a lot. A small (very small runner's) rain jacket, long top, perhaps also a pair of tights would max it out I think, and some of that might have to be outside the pouch between it and the elastic cords.

    But for a long race, you could at least keep a light rain top, synthetic hat, headlamp, and light gloves. It's definitely not the item I choose on long unsupported runs in the mountains, but it is the item I choose to go light and fast when I want a pack.

    1. KenZ

      Oh, I tighten the bejesus out of them WITHOUT the bottle in the shorts. That way when you shove the bottle down the back, it's pretty cinched in there.

      It'd definitely bounce some, but certainly shouldn't bounce more than, say, a waist belt bottle holder, and I personally think it bounces less. The shorts drawstring definitely cuts into the front of your hips a bit from being so tight, but, just like a heart rate monitor, it goes from super annoying to noticing it's there to being completely oblivious that you have it on after about an hour.

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