UltrAspire Molecular Belt System (MBS) Review

UltrAspire has led a resurgence in innovative hydration systems for runners. One of its biggest innovations is the UltrAspire Molecular Belt System (MBS), a collection of interchangeable components for waist-belt hydration and storage needs. Learn about the MBS system and some of its components and configurations in the following video.

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UltrAspire Molecular Belt System (MBS) Review Transcript

Welcome to Trail Trials, the video review section of iRunFar. My name is Travis Liles and in this video we are going to be taking a look at the UltrAspire MBS collection.

UltrAspire came on the scene a few years ago introducing some new takes and some new spins on how we carry our hydration, how we carry our gear, how we carry our calories with us. I think that the Molecular Belt System (MBS) is a perfect example of recognizing that each of us are individuals, and we’re unique in what we want to have and what works best for us on race day or training or varying by distance. So what we’re going to do in this review is look less at one individual component and really think about all of these components and how they’re going to work together and how they’re going to hopefully come up with a way that gives you the best options to carry your stuff.

The MBS system is defined by two parts—one is the core, and two is the connector. You can think of the core as the piece that is going to ride on your back. The connector is the piece that rides on your front. I’ll caveat that by saying you can wear it however you want. That’s really just how these things are designed and labeled on the website. We have three core components and two connector components with us today. UltrAspire has 5 connectors and 10 cores, so there are up to 50 different options that you can have. What we’ll do is take a look at each of these different components individually and then show a couple ways in which they’re going to work together.

Let’s start off by talking about our core component. This is easily defined by a metal hook or metal loop on one end and another nylon loop on the other side. These are going to interact with our connector pieces to create an entire belt system. This is the Zeta. The Zeta is a large mesh pocket. We have a drain hole on the bottom and stretchy mesh on the front. So we can fit a lot of stuff in this pocket. I have two hands in there right now and we can see there’s a lot of room left in there. Jackets, gels, hats, sunglasses, GPS, smartphones—you can put all that stuff in here with room to spare. There are two divider pockets in the back, so if you want to keep some of that stuff from mixing together or you want to reach in and grab it really quickly, you can. Then it’s closed up by using a magnet—the magnet is something you will see as a recurring product throughout the UltrAspire lines whether you’re talking about hydration or their belts. Magnets seem to be there a lot which I like because they close on their own. If you forget to close them, it will snap together. This thing does a better job of holding large items instead of small items because it makes a bit of a gap here. If I was going to wear this on race day instead of training, I’d definitely put some Velcro-type hits right here that I could make sure that that would stay closed. A lot of stuff can fit inside of the Zeta.

Next up is the Nerve. The Nerve is a single bottle holder. There are multiple bottle holders in 20-ounce sizes and 10-ounce sizes and lots of different ways you can have this type. But this type is one of the examples of one of their bottle packs. This has an UltrAspire bottle in it; it will also accommodate your standard 20 oz bottles. The UltrAspire bottles have a neck on them that is curved so that when you’re drinking out of them, you can really get to every last drop. This is standard in the way that we’re carrying a bottle in the back. This is going to sit in the middle of your back at an angle which will hopefully keep it from jiggling around. We have a shock cord on the side. The shock cord is going to be there for us to put a jacket, hat, or gloves and be able to strap that down. Once we do that, instead of having that annoying piece flopping around and hitting our side, we have a really great feature of having a pocket here to stuff that inside of. You could also fit a gel in there or even some electrolytes in a baggie (I’ve learned.). So that’s another option for carrying. Over on the opposite side we have a flat pocket that’s good for small items like gels, electrolyte pills, even a bar or a waffle could fit inside of that pocket. Again, we see our core hooks or connection points on here.

Our last piece on the core is the Reflex. The Reflex is super simple. It’s a piece of fabric with some reflective hits on it. This you will see comes in handy when connecting it to one of our connector components when we don’t want to have anything extra; we don’t want to have a pocket; we don’t want to have a bottle; we just want to have that pouch or accessibility in the front capped off with a nice reflective hit across the back. I will note that there is a sister-component to this that is just a belt that would allow you to have just a belt portion and combine that with a pocket or one of the bottle functions. So there are a lot of different ways to mix and match.

Next up, we will look at the Cell (connector). The Cell is probably one of my favorite pieces for training and that’s because you can carry a lot of stuff but it’s not cumbersome. Another reoccurring thing you see on these UltrAspires is the quiet pull zippers with the big tabs. These are perfect for winter when your hands are cold and you have big gloves and you still want to be able to pull on that zipper. You’re not sitting there fiddling around with it. These are going to be easy to grab and close and open. Inside of this we have enough room for again a couple of hands. So we can see when you look at it from the side, you can fit quite a bit of stuff in here—a phone, some power bars if you want. Then there are separator pockets in the back to keep those things separate. This is just less than the Zeta gives us but still plenty of calories or items that you can carry inside of this. Next up, we have two more shock cords. On either side of this we can put some gloves or smaller items that we want to push down, or we can loop these two across the front and have a way of putting a jacket or an extra shirt in here keeping it tight and keeping it secure. There are some nice hits and features that are available on this.

Lastly, we’ll look at the Electron. The Electron is a really simple, minimalist belt. You can carry about 5 ounces of calories in here. You can do that in a flask which I’ve pre-loaded in here to show you, or you can stuff about 5 gels in there. I’d say the tipping point is about 5 oz. So whether that’s in a flask or stuffing 5 gels that make up 5 oz, that’s really about your cap on this type of thing. Then you have something that we saw on our review of the Surge hydration pack from UltrAspire: this electrolyte pocket. Again, it uses that magnet to snap down and you can put electrolyte pills in here or an MP3 player or some other small things will fit in that, too.

So now that we’ve seen some of the core components in the back and some of the connector components in the front, we’ll go ahead and put those together to maybe give you some ideas on how you can use these on race day or in training. One of my favorite combinations of these is to use the Reflex and the Electron. What we have on the connector component are this red anodized aluminum and then we have the belt side of things. You won’t be able to see this, but these are sized. You can have everything from an XS which is waist size 24-28 inches all the way up to an XL which is 36-42 inch waist. You’re not going to find a big piece of fabric flapping around one side or a belt being too small for you. Again, they’re increasing the number of options and the best way available for you to carry. We can simply take the pocket and snap that in on one side, then move to our other side. We’re going to thread that through our metal loop. Then we have a really great way of being able to carry some of our items with us. One of the things I want to point out while we’re looking at it is that these belts have a contour to them. So instead of being a perfectly flat circle, they tend to have a bit of a dip or a “U-shape” which helps them ride on your hips a little bit lower and keeps them from bouncing. This is a great use of this belt for a 20-mile run. You want to carry some calories with you, but you don’t need a bunch of extraneous stuff—this is perfect for that.

Let’s say maybe you’ve got a little more ground to cover or you need to carry more stuff with you. That’s when you could take something like these two components (Zeta + Cell) and place those together. Now you’ve got the medium-size pocket in the front with the shock cord and you’re carrying some stuff there. You’ve got another water bottle in the back with another shock cord and more pockets. So this is more of a longer-distance type thing especially if you’re carrying handhelds also. Now you can carry 60 ounces of water with you and really be able to cover a lot of things.

Again, we only have several components here. There are dual water bottle holders; there’s single; there’s small. There are other pocket sizes available. There are a lot of different options to hopefully help you on race day come up with the right combination. If you’re interested in any of these, please go out to www.UltrAspire.net to take a look at the other options available and to find the right recipe for you. If you’ve got any experience with UltrAspire packs and combinations that you feel work well or just comments in general, please leave a comment. Thanks for watching. We’ll catch you next time.

Travis Liles

resides in Portland, Oregon where he is a husband, father, and a technical specialist for a software company. In his spare time, he is exploring his new home in the Pacific Northwest, getting more vertical but still not living in the thin air, while producing "Trail Trials with Travis Liles" video gear reviews for iRunFar.

There are 19 comments

  1. ChrisG

    I really like the MBS system. I bought my system last summer. I have two cores (Synapse and Reflex) and 1 connector (the Cell). I wear the Reflex + Cell with a backpack that does not have belt pocket(s). The Synapse + Cell can hold a ton of stuff and wears pretty nice.

    A few issues

    – I lost one of the shock cords on the Cell. I should contact UltrAspire for a replacement.

    – The hook mechanism between the Synapse and Cell will sometimes slip and waist pack falls off.

    – The water bottles. The ergonomics are super nice BUT the lids do not screw on cleanly. I normally need to flick my bottle to make sure the lid is on correctly. Has this issue been fixed on the new bottles? I had the same problem with 26 ounce bottles that came with my now lost UltrAspire Fastpack.


  2. Travis

    Chris, I had some of the same issues with the water bottles. I talked to one of the Ultraspire athletes last year and mentioned that they had given that feedback to the design team. I think.. think, it has been addressed.

  3. James Brennan

    havent tried the system bc I tried the bottle and wasnt that crazy about it. Pls keep posting reviews like this…very helpful. may try the zeta

  4. KenZ

    Thanks for info/review. Got one quick question: I've been looking at the Impulse as a more minimal 100 mile system; the website has it listed under the MBS, but the product and video seem to show that in the case of the Impulse, the belt is attached and it's not part of the modular system. True? Or is the Impulse just the core which can be used with any of the connectors?

  5. Nelson Prater

    I really want to like and use my UltrAspire handheld. But, the first time I used it, I tripped and fell, which is not all that unusual for me, and the top blew off (can't seem to get the top on tight)and the contents spewed leaving me bone dry for a long ways. And, when I got back to my truck later that day to go home, my key which was in the zipperless pouch was gone, too. I do like this handheld so much, though, I may figure out how to carry my key some other way, and work on the cap some.

  6. Jim Kavanagh

    I'd like to give a warning to those thinking of buying the connectors directly from the Ultraspire website (and potentially from stores, if you're that fortunate). It turns out that they have quite a few "defects" in circulation, which run very small (the medium size barely fit my 31 inch waist). I ordered 3 different connectors, and they all had the same issue.

    Skylar, from Ultraspire, explained the problem and issued me the RMA to return them. However, despite ordering the belts 2 months ago, I am still waiting to run with them. So, even though they KNEW a large quantity of their belts were defective, they still sent them out anyway. For my inconvenience, they sent the replacements via what must be the Pony Express, because in two weeks, they haven't made it past the Mississippi.

    I would recommend against ordering any MBS connectors, as there is no way to know if they are defective or not. For me, I won't buy another product from them (I already had a couple vests), because they are knowingly distributing bad products. I sent mine back and I'm willing to bet they will sell them again to another unsuspecting ultrarunner. It's just my opinion, but our little niche demands quality above all else, and for their prices, they should be doing everything they can to do just that. I'm extremely disappointed.

    This was their initial reply, so you can judge for yourself (I may be a little too frustrated)…

    We are aware of this problem.  It was a factory defect. Everything was cut small, and not to size.  Somewhat fortunately, most people who use the MBS were able to walk into a store and actually try them on for size.  Unfortunately for you, as well as numerous online customers, it doesn't work so well…  Needless to say, I'm a bit embarrassed.

    Here's what I can do, however.  Attached to this e-mail is an RMA form (return authorization).  Print it, and fill it out to the best of your ability, using RMA#xxxxxxx.  Make sure you mark 'exchange', and in the comments write 'exchange for larger size'.

    Once you receive the Cell you're waiting on, just return them to our warehouse using the address on the RMA form, and make sure you include the form itself with the shipment.  As soon as  we receive them, we'll swap them out for a larger size, and we'll send them your way (and we'll cover the ridiculously high shipping charges this time ;) ).

    Finally, be expecting another e-mail from me tomorrow.  I'm unable to send one today because of 'end of day' stipulations with UPS, but I'm going to issue a call tag for you that will cover shipping costs from your location to our warehouse.  I've made a note of it, and will do by absolute best not to forget… but if I do, feel free to send me an irate e-mail on Friday.

    I'm hoping this amount of information doesn't surpass your threshold for pain…  I'd really like for you to be as happy as possible, and I'd really like for you to be able to enjoy the products you purchased specifically to be used, rather than returned.

    Let me know if you have any further concerns, and I truly hope you enjoy your holiday!

    Thank you,

    Skyler Starnes

    1. KenZ

      Well damn. OK, that's good info. I still want the Impulse, but now I'm definitely going to try it in a store first instead of ordering direct.

      1. SkyDog

        KenZ, I actually sent an email about the Impulse yesterday wondering when the "newer" version will be available. I had heard there were issues with the connecting hook coming loose. This Skyler guy emailed me right back and told me he actually has the new version in and if I wanted to order it to call him, which I did. Skyler said there WAS issues with the hook mechanism. They fixed that and updated the mesh material to breathe better. I believe he said the updated Impulse is a little lighter as well….

        Anyway, I've been waiting a long time to try one, but I wanted to actually talk to someone there to make sure I'm not getting sent an "old" version with issues… Now today, after reading Jim's comments, I'll be crossing my damn fingers all goes well…

        1. KenZ

          Interesting. The plot thickens. Do write back here when you get it and let us know if it's better, or at least that it fits. Lighter is better as well, although it's still unclear from their website if it's a one piece or if we have to get a connector belt? I'm guessing from what you wrote above that this one is a one piece, even though it's listed in the MBS section implying that it's not?

          1. SkyDog

            Ken, it is my understanding that it's a one piece, one size fits all. I think they could do a better job managing their web page. I will update ya with info when I try it out.

  7. SkyDog

    For a quick update for anyone that cares… Got my Impulse in yesterday. I am very pleased with the quality of the belt as well as the bottles. It is labeled as "Revised". The fit is light and very comfortable. It IS a one piece, and it seems to be adjustable to fit large and small sizes. I haven't worn it with the bottles filled, but I'm tempted to try it at Rocky Raccoon next week. Hope this helps.

    1. KenZ

      I care! Thanks, do report back, but this pretty much cinches it for me. It seems like a really great rig, and during the day on 100's, I kinda don't want to wear a shirt. But a pack, like my beloved Nathan, rubs the skin off my back if I take the shirt off, and most waist packs/waist bottle systems just seem to bounce too much. This looks more secure and solid, plus faster to fill at aid stations than 4x small bottles.

  8. DavidT

    I have the Electron + Synapse, which I got in Late November of 2012. I've experience the same issues with the hook mechanism. I typically have at least one slip per run. I believe the sizing is correct as I'm right in the middle of the range. I've also tried to tighten it but that doesn't guarantee a non-slip.

    The 20oz bottle that came with it also has another issue, the twist cap doesn't always close, I find that I have to sometimes push it down until I hear a click, then twist it.

    I finally got around to contacting them today and will report back.

  9. KenZ

    To give them some credit, I just checked their webpage, and they've updated it in regards to the Impulse in two ways:

    1. They now have it listed in Non-MBS items

    2. The have an explicit statement on the Impulse item page that it is not MBS.

    So I gotta give them props for updating, possibly due to the postings here. I'll be buying mine soon (just gotta haul my butt over to ZombieRunner's store; that's a place worth paying a little extra to support).

    1. KenZ

      Oh yeah, I did. There was some confusion there too. I went to buy it at my local store (gotta love it when Zombie Runner is your local store!) but I was ultra-paranoid so I brought the updated P/N with me. Zombie Runner assured me it was the new model, but the P/N on the label was the old P/N. Turns out a limited number of the new model had the old P/N on the packaging (seriously)… so I bought it after confirmation with UltrAspire.

      OK, so here's my take:

      1. I really really like it. It will definitely be my go-to hydration solution for my upcoming 50k this month and 100k in May. After that, I'll know if I want to use it for a 100m later in the year. The Impulse vs. Nathan HPL #020 vs. Mountain Hardware Race Vest for 100 milers will likely be made on a case-by-case basis considering required items to carry, temperature/clothing level, distance between aid stations, etc.

      2. Am I crazy, or does it seem heavier than it needs to be? I'm not saying it's "heavy" by any stretch, but it FEELS like there's just too much beef in the bottle holder padding. Leave a small strip of padding near the top to hold the bottle, but the rest should be made out of cuben… I'll be they could easily cut 3-4oz off the sucker if they tried. Of course, some prefer beefier, totally bomb-proof products so maybe I'm being a bit too much of a weight weenie.

      3. Not a huge fan of the bottles. They're not terrible, but I don't see/feel the magnet thing in the bottom doing jack, I don't like the twist valves (can't pull with teeth; Amphipod's push-pull closures are water tight, so why did UA have to go with the twist mechanism?), and if you squeeze the bottles too high up, the top pops off and dumps all your water down your front! To keep the tops from leaking all over you or falling off, you have to squeeze mid-to-lower down the bottle, and then they're fine. That'll be an easy thing to re-train myself to do, but it's annoying.

      Lastly, while the zip cord in the back should be great for holding a jacket or shirt, I'll likely add some super lightweight flexible mesh for a "pocket" that the zipcord cinches down. I just worry if I shove a jacket and shirt in there, and I'm bombing downhill, I could lose something and not know it. For 0.02oz, they could add a stretchy mesh integrated with the zipcord to ensure that you don't lose stuff. Not saying what they have won't work fine, but I'm not feeling 100% confident.

      Overall I'm happy with the purchase, and I would make it again. Looking forward to racing with it. It kind of has me motivated to make my own variant that's ultra-light weight, but talk is cheap, and my industrial sewing machine stands idle….

  10. KenZ

    Just got my Impulse, and as I noted below in response to SkyDog, any squeezing up near the top pops the cap off the top and all your water is gone. You don't have to fall to do this, just try to take a drink from it squeezing near the lid, and you'll end up drenched in water. Easy to avoid by squeezing lower. A wetter, colder me learned that recently… not surprising that a fall pops the cap off.

  11. Jim

    Great review Travis. What would you recommend for an Adventure Race

    INDIVIDUAL GEAR (to be carried by EACH RACER at all times during the race):

    Hydration Pack (40 oz. minimum)

    Headlamp with fully charged batteries


    Emergency Blanket

    1 Flint or Lighter

    Waterproof Jacket

    Fleece Jacket or Pullover (cotton cannot be substituted for fleece)

    Fleece or Synthetic Hat (no cotton and must cover ears)

    Dry Bag (big enough to hold all of the gear in your pack)

    Rain Poncho (optional – above items are mandatory)

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