Synaptic 2.0 Waist Pack

(24 customer reviews)


The Synaptic 2.0 waist pack is highly versatile and ideal for most training runs and races. The versatility comes from access to all compartments without taking the belt off. This pack provides the ability to carry hydration, nutrition, home essentials, and is equipped with Z-pole attachments all while remaining very lightweight when loaded down. The original Synaptic was Ultrarunning Magazines’s Top Pick for stability; the Synaptic 2.0 features the same weight distribution ratio and conical belt shape but with upgraded functionality. This pack comes with an UltraFlask 550 Hybrid Bottle in the holster. This bottle is simple, intuitive, and the construction allows for easy access to remove or holster the bottle on the go allowing for a more regulated hydration schedule. This pack features a mesh zippered pocket and additional quick stash pocket on the side of the holster. The front 4-way stretch mesh pocket has capacity for a large cell phone but remains flat even when fully loaded. Shock cord attachments on the front give you carrying options for Z-poles or layers of clothing you want to carry with you. One size fits most.


SKU: UA204 Category:


ErgoFit Waist

Recommended Use:
Racing and training; 1 hour between refueling stops.


• Dual-sided adjustment for good sizing range with single speed hook access for taking waist belt on and off.
• 4-way stretch mesh pocket is large enough for cell phone or energy foods with tuck away jacket straps perfect for extra clothing or Z-poles.
• Mechanical locking holster for easy right handed access. Bottle rides close to the body for a comfortable stable ride.
• Small flat zippered pocket next to holster to secure keys or other essential items.

Fit: Unisex
Size: Universal
Color options: Lagoon/Navy
Hydration (included):  1 x UltraFlask 550
Capacity: 52 c.i. (.85 L)

Additional information

Weight .59 lbs
Dimensions 15 × 10 × 5 in


24 reviews for Synaptic 2.0 Waist Pack

  1. Olan

    I would like to start by saying that I have avoided using waist belts/packs for a long time. I tried one out a few years ago and what I disliked most about the experience was that I felt like I was fighting with the gear the whole time. It did not feel natural at all.

    I decided to take a chance with the Synaptic 2.0 because I needed something for my shorter training runs. I have used handheld bottles for years, but prefer to be hands free. At first, I was a little concerned because I was not used to the feeling of a bottle resting against my lower back, something that I found particularly noticeable when standing still. But I was pleasantly surprised when I didn’t really feel a thing once I started running.

    In terms of fit, this waist pack is amazing. The dual adjustment straps ensure that I can get a comfortable, even, and natural fit. The pack feels super secure with no bounce and the way it molds to the body almost makes you forget that it is there. I think it also worth mentioning that I didn’t really have to adjust the straps once they were set.

    In terms of storage, the zippered mesh pocket is large enough to fit a drivers license/cash/card/key comfortably. I was also pleased that the front pouch could hold my phone and still keep a low profile. I even managed to fit 3 gels in with the phone with no issue. Inevitably on short training runs we’re often forced to make choices on what to bring and what to leave behind. I really love that the Synaptic 2.0 is versatile and gives you more options to consider when it comes to carrying capacity.

    I like that the bottle is very easy to holster and that it remains static throughout the run. Bottle removal, however, is user dependent…everyone will likely have a different method based on what is most comfortable for them. I find the easiest way is to grip and pull from the top with one hand while pushing the bottle up from the bottom with the other simultaneously.

    In an effort to be transparent, I have not (needed to) use the quick stash pocket on the outside of the holster (yet). This is likely because I prefer that my “workspace” remains in front, but I can see how this pocket would be useful to store empty gels packets/trash until you can dispose of it properly.

    All that said, I am very happy with this product and am excited that it is part of my gear lineup. I think the Synaptic 2.0 is a fantastic option for those looking for a hands-free, high capacity solution for shorter runs and races.

  2. Spenser Snow Canada

    The first Synaptic was the first waist pack I’d run with where I did not experience any bounce when the belt was adjusted properly. I wore that belt for the first 50 miles of the Wasatch 100 and loved the feeling of my upper body being free (especially in the heat!). I was able to tuck empty soft flasks under the belt and 12 gels in the front pocket. My main complaint about the first edition was that the belt was difficult to cinch down to my 31″ waist size, which also meant that I had a lot of extra material after pulling the belt tight and nowhere to put it. The belt also was not very flexible, and sometimes came loose as I ran.

    The Synaptic 2.0 is a huge improvement on an already solid waist belt. The belt now fits my waist size and there is a small loop where extra material can be tucked. The new materials provide some stretch without compromising on the secure, no-bounce feel. The mesh front pocket keeps nutrition and gear flatter and closer to the body, and the zipper is removed so the access is similar to the Fitted Race Belt. I now use the small pouch near the bottle to carry an extra “emergency” gel that’s easy to forget about when I don’t need it but assuring to know that it’s there when I do.

    I tested this belt at The Capstone 50k and spent the first few miles playing around with the fit, then didn’t need to make any adjustments for the rest of the race. The course is very technical, with steep downhills over slickrock, and the pack remained secure the entire time. I wore the belt directly against my skin and experienced no chafing or discomfort. The bottle stuck out the back outside of my shirt for easy access. I found it easier to remove with the left hand and replace with the right. What I was most impressed with was that I was able to carry all my nutrition and gear for the entire race in such a low profile belt! I carried six gels, gloves, and a light jacket, and only had to refill/replace my water bottle at aid stations. It was a perfect trial run and I now feel confident that I’ll be using this at 100-milers in 2020 where carrying more nutrition and gear between drop bags is essential.

    I haven’t had a chance to test the belt with a waist light but I’m curious to see how that works. I also haven’t tested the front loops with trekking poles, but I imagine the flatter profile on the front will improve the security of the poles from the first Synaptic.

    My only suggestion for the Synaptic 2.0 is to offer the option to purchase the hybrid flask separately. Anyone who’s purchased UltrAspire packs/belts in the past probably has a handful of these already!

    I highly recommend this belt for any run from short training runs to 100 miles. It’s recommended for 1-hour between aid stations, which I think makes sense. A creative solution to be able to carry more water is to carry a soft flask or two in hand that can be tucked into the belt or stashed in the front pocket when not in use.

  3. Beth Ann

    I needed something for shorter runs where I didn’t want to wear a hydration pack or a carry a handheld. I decided to give the Synaptic 2.0 a try. I’ve done several short runs and have to say this exceeds my expectations for a waist belt. The nylon belt is comfortable, not bouncy and easy to adjust. The water bottle is really easy to put back into the fitted pocket and I’ve found even when the water bottle is full, there is minimal jiggle. I like the minimalist feel the Synaptic 2.0 has, but still able to put a few items in the pockets if needed.

  4. Matt S

    Ultraspire hit the ball out of the park with the synaptic 2.0. The shape of the bottle plus the angle that it’s held at is the perfect position to prevent sloshing around or feeling heavy when full.
    The pockets are perfect for holding a cellphone, keys and a gel or two.
    Great for mid sized adventures that don’t quite require a running vest.

  5. Pete Gonzales (verified owner)

    I decided to give one more waist pack a try, have tried several over the years with no success, they all bounce so much I threw them in the closet or gave them away, Wow!!, am I glad I tried the Synaptic 2.0, the best I’ve ever tried, I almost forget it’s there, no bounce at all, able to carry everything I need , for an unassisted run under 2 hrs. The loops in the front are awesome, I wear gloves for morning runs, my hands get cold easily, but after warming up I stick them under the loops, synch them down and forget about them, a great product.

  6. Russ Schwartz (verified owner)

    Never ran with a belt that had hydration but as my runs become longer, I felt it was necessary. I love this belt. It is comfortable and light.

    My only issue is that it was missing a clip that keeps the end of the belt from being loose.

  7. dusty dustyn

    Absolutely 5 Star – in every way. Absolutely love it! Easy to adjust to fit. Never slips around. Can pull the bottle out and drink on the run, and slip it back in place. I never even notice i’ts there. I’ve uses the elastic ties in front to hold a windbreaker that I took off mid-run. Pouch holds my iPhone 10 (smaller size), and gel. Inner dividers mean I coldstore capsules as well. Smaller zip pocket fits large car key.

  8. kevin quinlan

    No negative issues with it over four 10-ish mile trail runs. Bottle is a tiny bit tricky to remove from its holster, but only barely, and that probably helps ensure that it doesn’t fall out.

  9. Dallin Draney

    I love this pack for my sub 10 mile runs. Holds my phone, keys and gels plus the straps hold my light jacket when I start in colder mornings. I would highly recommend this pack.

  10. KZ (verified owner)

    I bought this for my mom in AZ because hydration vests are just too hot for her daily walks and runs in the 100+ temps. She loves the fit of the waist pack–secure and comfortable and no bounce–the storage for keys and water is perfect as well–her frozen water bottle thaws perfectly but stays cool which is a huge bonus, and her hands stay free. Unfortunately, but phone pocket doesn’t fit an iPhone 11which is a huge bummer when she runs… while walking, she can put the phone vertical and it stays secure but not while running. Perhaps the next installment can be stretchier for the larger phones.

  11. Chris

    After a half-dozen runs, this gets two big thumbs up: The Synaptic 2.0 is deceptively roomy. I’m able to cram 5-6 gels using the back zippered and elastic pockets, and I could put another 4-5 in the front pouch if I don’t take my phone. Also, I’m not sure how hard folks are trying to get their iPhone 11s in the front pouch. It absolutely does have enough room for my iPhone 11. I don’t use trekking poles, but I’m sure the front bungees could handle them with ease. I use them to strap down a rain or wind shell. Most importantly, there’s no bounce on the bottle holster (assuming you’ve cinched the belt snugly), which is the real reason I was in the market after years of disappointment from UD and others. The holster will accommodate smaller bottles as well, as I’m able to holster my Nathan 12oz-er in there without hassle. The one downside on the Synaptic is the bottle spout — be careful when drawing from it. It’s aggressive, and if you turn it upside down you’ll lose a couple of ounces before the spout seems to seal.

    The success of this model has me eyeing the Speedgoat for two bottles. Nice job, UltrAspire.

  12. Jake

    I’ve had this now for about 6 months and I’m absolutely loving it. I’ve used a similar belt before and it didn’t really work for me, so I was reluctant to try again, especially at this price. But after having used this for a few hundred miles now, I’ve found it’s worth every penny. I’m even considering dishing out even more and going for the Speedgoat 3.0 as well. These belts have zero bounce and enough room for whatever you need. I’ve taken it up to 15 miles at a time and it was totally sufficient, having room for my phone (iPhone 11, a gu, waffle, keys, and the bottle). I love this thing and I will keep an eye out for whatever other new gear Ultraspire puts out.

    The one problem I’ve had with it is when it’s up against bare skin, you have to make sure it is positioned in the exact right place, otherwise I experienced some chafing. But don’t let that stop you from trying this thing out.

  13. James Campbell

    I was honestly skeptical about a hydration waist belt at first as all I could envision was a lot of serious bounce as you run, but reading other reviews I decided to take the plunge on this waist belt.

    All I can is that UltrAspire have far exceeded my expectations, and have made an amazing waist belt with this pack. Once you find your sweet spot, the pack sits perfectly against your body and doesn’t bounce at all, even with a full bottle and a full front pocket.

    The bottle system is cleverly done. It consists of a stiff foam pocket that has a ‘locking’ mechanism to ensure your bottle will never come out no matter what. This is easy to use once you figure out a way to get the bottle out that works for you. For me, I personally push from the bottom with my left hand and grab it from the top with my right, which takes no time once you get used to it. It is also easy to put the bottle back in and ‘lock’ it back into place. The front pocket is deceptively roomy too. I’ve managed to fit my phone, some tailwind sticks, a buff and a pair of gloves and the waist belt was still comfortable.

    All in all, a great waist belt. Great job, UltrAspire!

  14. Jenny Velocitas

    Bounce? None here. You don’t even notice it’s there most of the time!

    Storage? Yes! and it can hold my huge phone (Samsung S20+) with no problem at all and still have room for more.

    Bottle system? No slosh, no problems, perfect!

    You really can’t go wrong with this one! I’ve only used this on shorter runs, but I can imagine it would hold up just as well on long runs. Don’t wait, get one now! You won’t regret it!

  15. Cody

    I’ve been using this waist vest for the past few weeks on various terrain and distances and it has been great. Super easy to adjust, access pockets and grab hydration on the go.
    I originally wanted this for summer runs because I am a heavy sweater and vests can sometimes get hot…its hot and humid where I live…I thought this was a nice addition to handhelds and feel like I made the right choice.
    Also, like others have said, there is basically no bounce and just enough storage for most training runs (hydration, a few gels, phone and you could use the pole holders if you need to shed layers)
    Based on the storage and amount of fluid this holds, I’m going to be using this very often – money well spent!

  16. Christine Duran-Garcia

    My go-to for hydration! I am in love with this waist belt. It fits so comfortably and stays put on my hips. Very easy to adjust so you can get a great fit.

    There’s a surprising amount of storage on this belt with two pockets. You can even fit a large smartphone in the larger zipper pocket and a gel or two. I really like the stretchy cords to hold lightweight coats, gloves, etc. The 550mL flask is a great size for up to about 90 minutes of running, for me. What a great piece of gear to have in the rotation!

  17. Kate

    This waist belt is great, I wish I bought it sooner. The materials are excellent quality and you can tell each of the features have been well thought out. I use this belt for short (<1 hr) runs with my dog so that I can carry water & treats for him plus my keys and phone. I also use this belt for longer solo runs (~2 hrs) and it holds everything I need and is comfortable. I even used it on a 2.5 hr run with no shirt on and it didn't chafe!! I do find myself adjusting the fit of the belt every so often as it slides up a bit, but the straps are easy enough to adjust on the go.

  18. Ethan

    All the positive reviews are right! I’ve used this belt for trail and road running the last couple months (maybe 150 miles) and I couldn’t be more pleased. It is super comfortable and feels like it is going to last forever. My waist is only about a 32, so I looped the hook-side of the belt strap back through a couple times to get rid of the floppy tail. If you wear this over a slippery nylon layer it rides up a little, but I can’t imagine a design that wouldn’t. Luckily it’s small enough that if I wear a slippery layer I just put it on over the pack. Personally I haven’t had to adjust the belt once since buying it. The stretch cords are awesome, and I frequently use them for a hat, gloves, or even a very lightweight windshirt or thermal layer. The thing is so comfortable I’ll even wear it on shorter runs because it’s nice to have the water and is so handy for the phone and keys. Big fan.

  19. Michael M

    Love this waist belt. Got it for my 50 mile+ attempt in November as it was on a 2.5 mile loop course and I didn’t want to carry any excessive weight as I could refuel every lap. It worked flawlessly and is my go to for shorter events. You won’t be disappointed

  20. Anya

    Had the Synaptic for a few months now- wanted to see how it did across the board before a review. Used it for cross country skiing and 10/10 would recommend. Also use it for runs when I don’t want to bring my pack. It’s nice to switch it up! It does ride up a little after a while when running, but is easy enough to adjust and move back down mid-stride when that happens. Has room for phone and keys and even a snack!

  21. Daniel (verified owner)

    Nice light pack. Fits nice and snug with no bouncing. If you’re a big person trying to get in shape. May not fit. I’m at the maximum size and it barely fits. Bottle is a bit tough getting in and out, and I wish it would hold a regular water bottle better.

  22. Daniel Perez (verified owner)

    Just an update on my review from 8/18/22…….. I have to say Ultraspire has the best customer service I have ever encountered. Kudo’s to Zach for reading my review and reaching out to me to see if there was anything Ultraspire could do for me. After brief email with Zach, a week later, I received a new belt that was customized, so that it was a bit larger than what comes standard with the Synaptic. The new belt fits perfectly, and I am incredibly happy with the fit, and customer service that I have been provided. Thank you so much Zach.

  23. Joshua Bowles (verified owner)

    Nearly perfect, may be perfect as I learn to use it better. Perfect amount of storage space while maintaining minimalist feel. I’m new to running (1.5 years) and even newer to trail running (.5 years). Rather than researching, I jumped right in thinking I needed a back hydration pack so I bought a cheap one. It worked but I had so much water left over after my run and it was just making me hot. I avoided the waist packs because I thought they would be too uncomfortable with my waist/buttocks build. But on my trail running journey I found Trail Runner Nation podcast and listened to an episode with Bryce. His passion for making trail runner inspired/trail runner tested products intrigued me. I listened to him talk about back packs, handhelds and waist packs. I decided to take the plunge with this waist pack and haven’t regretted it! With the sloped structure it sits nice and snug on my hips. I can feel the bottle at the top of my buttocks when running but barely and that’s with a full 500mL bottle. I’ve worn it on a couple mountain hiking days and coming down the mountain on steep slopes required a seated shuffle the bottom of the bottle holder rubs. The material is minimalist but also strong so it seems it can take a bit of a beating.

    Cheers to many more UltrAspire purchases! Thank you to Bryce and team for continuing to focus on “custom” products that best serve athletes rather than cutting corners to mass produce and increase profits.

  24. Sam Kerns (verified owner)

    Really like the size/fit of this product. No bounce at all, and plenty of room for everything I need up to around the 20-mile mark (if there are places to refill H2O). I don’t love the color scheme, if I’m honest, but that’s totally a personal preference thing. The bottle requires a little tugging to pull out, but the benefit there is that it stays put when running. For reference, I’m about 6′ tall and have a 32″ waist and weight about 185 lbs. This fits no problem for me.

    Another note – if you plan to carry your phone in the front pocket, you’ll have a great experience, but you may be a touch low on space for gels, gummies, waffles, electrolytes, etc. This isn’t a huge issue, but just be aware that, for longer efforts where you need a lot of calories packed on you, you may need to forego your phone.

    This is definitely a “minimalist” waist pack (which I absolutely love) but it may not be for everyone. If you want to carry a lot with you or if your race requires an extensive gear list, you may want to look into a vest. But for middle-long efforts where you need to carry some water/nutrition or for races where you have regular access to aid stations, this is a fantastic waist pack for staying light and fast on the trails.

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