Stan's NoTubes Announces New Flow EX3 Rims & Wheelsets

Mar 18, 2019 at 9:56
by Stans NoTubes  


You’ve overshot everything and now you’re coming into the rock garden far to the right, way too fast and nowhere near your line. A whole lot of brake is the obvious answer here. Some hard braking might let you get things under control, pick your way through slowly and figure this out, except--wait. What if you’re one of the best riders in the world? What if this is a World Cup downhill run and every tenth of a second matters? Suddenly that root on the edge of the course is looking big enough to boost over the whole first section of rocks, cutting across the worst of it at an angle to put the bike back down in that gap between those last two rocks. You can keep the front wheel high and out of harm’s way, but whatever’s down there between those two rocks, your rear wheel is about to blast into it at Mach ten.

There aren’t many riders in the world who can put a wheel into that situation. A lot of us might feel like we’ve been there (and no doubt there’s something to be said for the truly gifted amateur bike manglers out there), but when it comes to exerting completely ridiculous forces on bike parts, only a rare group of riders can do it consistently. With so much attention on Instagram and edits, it’s easy to forget that testing and development are some of the most important things a sponsored rider can do to help a company make better products.

At Stan’s, we’ve been working with racers from day one. Some of the first BST rims we ever made shipped straight to XC riders at the 2004 Olympics, and for several years, we’ve worked closely with the best downhill racers in the world.

While the tubeless performance of the original Flow EX and Flow MK3 made them popular choices for downhill and enduro racing, neither of these rims were built specifically to handle the extreme forces generated by a season of downhill races or repeated enduro stages. The new Flow EX3 rim is unapologetically focused on descending and an ability to withstand the most severe riding conditions.

Over the years, we’ve done some pretty nerdy testing on our rims (like using CAT scans to see inside inflated tires on rims), but the Flow EX3 development included a more primitive component, too. Nearly every rim damaged by a pro during the 2017 and 2018 seasons was analyzed. Some damage was the type of thing we’ve seen for years with all brands of rims, but there are always some more interesting ones, too.

We took the most extreme examples and studied those closer, forensics-style, until we could figure out how to create tests capable of doing those same things to a rim consistently.

Once we were able to simulate the most extreme and unique impacts, the real work started. This more brutal testing of Stan’s and competitors’ rims and wheels taught us some very important things.

Part of what it took to replicate what we were seeing in the field was to take our “drop test” (that weighted wedge that slams down on an aired up tire and rim) and rig it to wreak more havoc on a rim than we ever had. As it turns out, the forces that can be exerted on a wheel on the Mont-Sainte-Ann World Cup DH course go well beyond "extreme" and into the realm of "catastrophic." Rims we tested, including our own Flow MK3, struggled to handle the new drop. What was surprising was that our classic Flow EX (that skinny old rim with the triple cavity internal design) actually did quite well in this test. In fact, it did better than many modern downhill-specific rims. When it came to resisting damage and maintaining a tubeless seal, the EX outperformed nearly everything we tried.

A Flow EX3 hiding behind a set MK3 graphics at the 2018 Whistler EWS round

We knew the MK3’s 6069 aluminum was 10-15% stronger than the 6061 alloy used in the EX generation, and we knew any new rim had to be wider than the old EX models, but the shape of the original EX rim inspired our engineers to incorporate the best elements of both generations into what would become the all new Flow EX3. Once we had a few prototypes, it was back onto bikes for real testing.

We’ve worked with Martin Maes and GT Factory Racing for years, and as the team had been developing new testing protocols for themselves they were instrumental in the refinement of the Flow EX3. With GT’s systematic approach to their pre-season testing, equipment selection and evaluation, the analysis of multiple rim designs became a natural part of the overall process. Martin Maes in particular was very familiar with the Flow MK3, so he had a solid foundation to understand everything we were trying to do with ride quality and rim shape on the new Flow EX3. The results speak for themselves.

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Only a handful of people knew it at the time, but the final version of the Flow EX3 rear wheel was on GT Factory pro Martin Maes’ bike when he took the win at the Whistler stop of the Enduro World Series in 2018 and again when he took the World Cup DH win in La Bresse.

La Parva Chile. Enduro World Series 1.
Martin Maes, Noga Korem and Wyn Masters of GT Factory Racing

Kyle Warner, three-time North American Enduro Tour winner, also played a role in the development of the Flow EX3. Racing most of his career as a privateer, one of the key characteristics Kyle looks for in his equipment is durability. When he found out the new rim designed for maximum durability was finally ready, Kyle couldn't think of a better place than Bootleg Canyon to put the Flow EX3 through the paces.

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For 2019, it’s also really special to be working with Rachel, Gee and Dan Atherton again. We’d worked closely with them on product development in the past, and much of what we learned through their partnership--especially about using rim shape to balance stiffness and compliance--went directly into the development of the Flow EX3. It means a lot to have the entire Atherton Bikes team running these new wheels.

Dan, Rachel and Gee Atheron - Photo: Moonhead Media

What did all this testing lead to? For starters, relative to the Flow MK3 we knew the Flow EX3 rim had to have a thicker spoke bed to withstand greater tension and forces on the spokes. Given the intent of the rim, it was also important to have the maximum available height inside the rim cavity so that when a monster impact does occur, the spokes have much further to compress before they could make contact with and damage the rim tape. Since making the profile of a rim taller also makes it stiffer radially (think of deep, ultra-stiff carbon aero road rims), the ride quality is often adversely affected and the rim more brittle, making it weaker in the long run than a lower-profile, more compliant rim shape. By thickening the spoke bed externally, we were able to balance both of these design goals without compromising the ride quality our rims are known for.

The Flow EX3 combines the best of both the MK3 and original EX

But the most important aspect of the Flow EX3 rim’s design is the Tiebeam: that inner bridge that runs across the inside of the rim. It’s this Tiebeam inner bridge that lets the Flow EX3 withstand impacts that would deform most rims to the point of air loss and structural failure. Even if a rider uses a tire insert, huge impacts can cause the side of most rims to fold, causing air loss and eventual rim failure. When you add the Tiebeam brace to support the patented low profile sidewalls on a Stan’s rim, you end up with a structure capable of resisting this folding force. The Flow EX3’s Tiebeam design means greater structural integrity, fewer dents and the best air retention in the industry. How much stronger were we able to make the new rim? Here's how competing rims and the new Flow EX3 performed in our catastrophic impact test.

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The Tiebeam design allowed us to achieve these tremendous strength increases with only a minimal increase in weight. The 27.5 Flow EX3 rim weighs 580g, while the 29 version weighs only 618g.

The Flow EX3 is also available as a rim only in 27.5" and 29" options

Combined with the added durability of 6069 aluminum and WideRight 29mm inner width optimized for 2.35” to 2.8” tires, the Flow EX3 expands the Stan’s Flow family to handle the most aggressive riding. Every World Cup DH and Enduro World Series win, every hour of testing, riding, and improving: it’s all here in the Flow EX3.

You can check out the full press release here.

MENTIONS: @StansNoTubes


  • 80 1
 Dan: What do I do with my hands?
Photographer: I don't know, look natural. Just hook your thumbs in your pockets or something.
Dan: Like this?
Photographer: ... um no ...
Dan: What ever, just take the picture.
  • 8 0
 I can't remember the last time I saw Dan smiling.
  • 11 4
 No, no, no.... Rach just farted, Gee is trying not to laugh and Dan is like "really guys? Again?"
  • 4 0
 @brassinne: Or they're comparing trophy cabinets.
  • 2 1
See, I stayed in an Airbnb in Llangynog and the old lady hosting us claimed to know the Athertons since they were kids. When I asked what they were like she said Dan was a lovely guy and Gee was the miserable one.
  • 1 0
 @rudymedea: I thought they were from Salisbury or something.
  • 33 3
 How many people are going to be pissed after building up what they thought was an EWS proven wheelset only to find out it wasn't actually the MK3 all the sites reported it to be?
  • 8 0
 Would definitely rather they labelled up prototypes as prototypes... Even if it creates some hype for the brand and they don't release it it can't be bad
  • 2 0
 I know I am.
  • 14 1
 The MK3 still is an EWS and DH proven wheelset. Not the latest proven wheelset, but a really good wheelset nonetheless.
  • 2 0
 @JoeRSB: Right on.... guess I’ll see if my MK3/Pro4's survive the park this summer.
  • 6 0
 @JoeRSB: Proven to not last two weeks for me. No surprise they figured out is wasn't nearly the rim the EX was and had to do a redesign.
  • 27 1
 EX is the way...but 471
  • 3 0
 Love mine, built with plain gauge spokes they are seriously tough.
  • 8 0
 I am running EX471 since 2014. They last. But my next rims will be either 511 or Newmen
  • 7 0
 @Matinsky: The way this ad is worded in the begining they are subtly taking stabs at DT. Actually, It's almost as if no wheel in history has ever survived a DH run according to them LoL

DT ex471/511 really are hard to beat for the price.
  • 2 0
 @m1dg3t: DT just need a bead lip to be perfect. I still run them.
  • 2 0
 @JohanG: Nothing is perfect, but they hold up just fine for WC racers.
  • 1 0
 @WAKIdesigns: I keep looking at the mavics. The deemax elite. The machined rim is just too cool!
  • 15 0
 "you can check out the full press release here". Or why bother, since you just read it in full on Pinkbike.

But seriously, I ran a Flow EX rear, paired to an Arch MK3 front last year on my trail bike. Guess I was on to something! Hopefully EX3 works out. Would be nice to see a lighter weight version, under 500g, for trail bike applications. That would be a serious affordable alternative to carbon.
  • 4 0
 A new Arch EX would be awesome, especially since lighter riders often don't need something like a Flow. My brother trashed his old Arch EX heavily and it's still rideable, even after getting a stick in his back wheel on a small jump and landing without 3/4 of the spokes...
  • 13 0
 Did anyone else find the EX more durable than the MK3? I've cracked both of them (after lots of abuse) but thought the EX lasted longer (EX was 27.5, MK3 was 29 for reference). Now over to websites to buy some outdated MK3's for backup!
  • 3 0
 Yes! But I can only speak for the Arch's. I had minimal issues with the EX level but managed to burn through two MK3's in he span of a month. Running Chromag Phase 30's now and they are holding up well! Excited to hear Stan's is borrowing some proven tech from the EX line!
  • 6 0
 My experience working in a shop has been that the EX, despite Stan's claims, were more durable than the MK3. We rebuilt a ton of busted MK3s and had plenty of customers tell us that their experience on the MK3s hadn't been as positive as on the EXs.
  • 1 0
 @waffleShirt: Hopefully the new ones are the best of both worlds (weight and durability).
  • 1 0
 My experience running several Flows is that the MK3 sidewall that grips the tire bead is substantially more resistant to dents than the EX, but the MK3 rim-bed/structure itself is easier to dent and bend.
  • 3 0
 Yep, OP. 27.5 to 27.5, me EX were totally bombproof. The MK3 much less so. Replaced with EX511.
  • 4 0
 I built up a pair of MK3's and I'm a heavy guy, they have been disappointing.
  • 4 0
 My mk3s won’t stay true for more than a few rides.
  • 2 0
 @waffleShirt: I second that. The MK3s seemed to dent very easily.
  • 4 0
 yeah, I don't think wider rims with the same or less weight can be equally as strong as some of those "old" 25 mm width offerings. That's why I don't like the trend of 30 mm inner width apparently being the new norm... if you want a reliable wheel you are back in the 2010-era weight region...
  • 1 0
 @jzPV: Nope. DT Swiss ex471 25mm ID very strong & light. You can read marketing/advertisements all you want.

Go YouTube Aaron Gwin Leogang flat tire 2014 Best advert.
  • 1 0
 @m1dg3t: Yeah, I was person... I'm talking about 30 mm ID rims with the same weight.
  • 13 1
 This is great, really great. But also have you guys figured out a way to make your rear hubs more reliable? I've had three fail, one broken axle and two where the ratchet ring separated from the hub shell and spun freely. Only use them as backup now.
  • 9 0
 Just throw the rims on some Hope hubs (if you're good with the noise). That combo will easily outlast the current standards until they change again.
  • 3 0
 i think they offer a steel inner axle for this reason
  • 1 0
 @vp27: That's what I currently have on there.
  • 1 0
 Yepp, 3 failed Neo freehubs and I finally just had my LBS build up the newest warranty wheel on a DT350. Probably the only truly bad mtb product I've very owned...
  • 1 0
 gumbytex I agree. Great rims but crap for hubs. I am a little behind you on the destructo-meter. One axle and a cracked hub shell. To their credit, they warrantied the wheel but eventually, I had to replace an axle. Easy to do but aggravating.
  • 3 5
 @vp27: If you do, please don't ride the Shore. I know Hope's are good quality, but that noise is brutal when you're out on the trail. Save it for the jump park.
  • 1 0
 @rrolly: That noise is brutal!? I used to think Hope made a lot of noise until I bought some I9! lol Now I find them to be too quiet! lol Don't you have predators to scare on the Shore... Razz
  • 11 2
 Remember young Bicycle Wizard. When one looks to the future, they first must reflect on the past.

  • 7 0
 Lots of reports of cracking Mk 3s around here...
  • 2 0
 Yup, lots of warranties as the spokes pull through the rim. Even running wheels with reduced tension doesn't work. Wonder if Stans Mk3EX is going back to winning ways....
  • 2 0
 Mk 3s were so soft. Rims were toast after no time. Same thing with all my buds who ran them.
  • 2 0
 @leewitzmtb: just sent a rear wheel back to my wheel builder. Stress cracks all around drive side nipples. Builder is no hack either and I weigh 165lbs. Way too soft.
  • 3 0
 I've got a 5 year old pair of Flow EX's on hope hubs built by Cookie at Chromag that I've smashed the crap out of and they're still running strong...EWS races, Trans-Provence, park laps, East Kootenay mega-shuttles, they just keep on ticking...glad to hear they've updated them, on my short list for next wheels for sure.
  • 8 1
  • 8 2
 Looks like a rim i once saw on a trek session
  • 4 1
 Just as I bought a new set of MK3’s w/Hope Pro 4’s this winter they come out with this.
Sonofabeach!!!! I hate it when I do that crap!!!
Whatever, I guess I’ll see if my MK3’s survive the park this summer.
  • 3 1
 I just got some new Kings with MK3 too!!! WTH
  • 1 0
 Wait until the stress cracks form around the spoke nipples on the drive side rear wheel. These rims are crap.
  • 1 0
 @richwag: Well that sucks! If this is the case then my rear wheel is going to die this summer. I sometimes don't pull my whips back fully, and I weigh 180lbs without riding gear.
I also bought a used rear MK3 as a spare, so now I have 3 of these neat rims. I can say that the Stan's rear hub has significantly more drag then my new Pro4 hub! I even made sure I cleaned and re greased the Stan's hub & Freehub with Dumonde Tech grease. I also had to tighten the spokes a bunch.
The Hope Pro4 is a superior hub compared to Stan's Neo.
What direction do the stress cracks emanate from. Radially from the spoke hole? Or towards the outside of the rim from the spoke hole?
  • 5 1
 Remember when Stan's was a tubeless conversion company and not a wheel company? Didn't see that coming. Anyone run Orange Seal in a Stan's rim?
  • 4 0
 I do, no issues.
  • 3 2
 I quit running Orange Seal because it smells disgusting, it leaves nasty residue on the rim and in the tire, and it makes gross reptavian molting skins. Oh, and it ate right through the sidewall of my tires, (Contis.) It also burped constantly, was just mediocre at sealing holes, and dried up in about two months. But, all the brohs seem to love it.
"Minyunz n Orange Seal, brah!"
I'm a weird case, though. I've left Stan's in a tire for a year and never had Stanimals, which the brohs also swear are unavoidable. I've also had really good luck with Bontrager, Finish Line, and Conti's Revo, all of which I have been assured are worthless. Climate, rim, temp, storage, and location probably all make a difference.
  • 2 0
 @SirLapLack: just interested: what's the climate, temperature and storage like in your case?
  • 1 0
 @SirLapLack: Finish Line is a real joke!!! I have a biiigggg bottle and don't know what to do with it... It doesn't work at all!! Dried up like 2 weeks after? lol It does not protect at all! My friend was so sorry that he convinced me to buy one at the same time as him... Was the same thing for him.

Only good thing about it is that it is easy to wash the rim and tire to be super clean after.
  • 3 0
 @SirLapLack: Huh, I run Conti Trail Kings with Orange Seal and I haven't had a single problem in over 4 years. In fact I forgot to put sealant in my rear tire, flatted at the end of a race, rode it out pinching the tire 9 times, filled it with Orange Seal, and got another few months out of it. Also, I talked to the owner of the company at interbike years back; that sealant on your sidewalls is just extra protection, meaning it's a good thing.

To each their own, but I swear by Orange Seal.
  • 2 0
 @Mac1987: SoCal, bikes stored inside, but no A/C in the summer
  • 1 0
 @SirLapLack: I guess it doesn't deal so well with higher temperatures then. Here in the Netherlands it's supposed to last much longer, but temperatures average around 5 degrees Celsius (41 F) in the winter and 20 (68 F) in the summer.
  • 4 2
 Such a mixed bag with Stans rims. I've heard good things on PB about them, but when I worked at a shop we stopped selling them. Both the Flow and Arch rims were really fragile in comparison to others. No problems with a DT Swiss, but always had troubles and failures with Stans. It's interesting to hear and see people using them for aggressive riding.
  • 3 1
 Nice press release.
While I’m more interested in Arch’s over Flows, whoever wrote this press release should be congratulated for bringing us along with Stan’s R&D journey, giving us a sneak-peak at some testing and substantiating Stan’s (hopeful) return to form. I wish more press releases were less like sales brochures and more like this.
  • 4 0
 Minimal increase in weight? Its about 100g heavier, heavier than all the other rims tested, would have been a better comparison to put it against the Dt dh rims instead
  • 5 0
 I'm more interested in the newmen German rims anyone try them ?
  • 3 0
 Can't wait to not buy these because I dented the living shit out of the first ones and destroyed the EX 2's Ex511's have been raging for 9 months! With no signs of stress.
  • 4 0
 Good on them for actually saying “yeah the old rev was definitely just a touch better. Sorry”
  • 4 1
 Too bad it's after many of us having shitty experiences with the mk3 after being sold a pile.
  • 1 0
 Sounds like they made all the right changes. The EX was a great rim despite being a touch narrow, but I went through 3 rear mk3 rims in 6 months with failures ranging from buckling to stress cracks at the nipples. I am actually back on EX and no problems this time either. Next set will be ex3 if they are as strong as ex, but as wide as mk3.
  • 2 0
 I love my arch ex's in my hardtail..4-5 years and I haven't knocked them out of true once, and I'm 200-220ish lbs.
  • 1 0
 I've literally just picked up a set of mk3s on pro4s for my DH bike. Now I read that even Stans says they're made of cheese. Guess I won't be getting rid of my old wheels just yet! Can't even replace with EX3s since they're not making 26 size.
  • 1 0
 Also remember that Stan is enforcing its trivial patent on those rim shapes against competitors:

"A diagram illustrating the patented features of Stan’s Notubes’ ZTR rim: a humped trough, shorter sidewalls and the absence of a conventional bead lock."
  • 3 0
 Would like to see this update on the Arch while keeping the weight under 500gm
  • 3 0
 Anyone notice the spokes still swinging around after the rim had bounced back 0.50 ???
  • 1 1
 I've had my Flow MK3s going on my third season with DT Swiss 350 hubs on my trail bike. I'm >200lbs so need something more than an Arch for just everyday riding for me. They've been great and no regrets. But...kinda sucks to hear Stan's say that their old EX rims performed worse than their MK3s. Interesting, as I remember them saying the opposite when they released the MK3 years ago. I'm hoping they still will keep a heavier duty trail version with 29ish mm ID in their lineup. This new EX3 is almost 100g heavier than the MK3, which is going to be noticeable on both ends while climbing.
What I hope Stan's does improve upon is the need to tighten spokes up after basically every ride. I had my shop fix this by applying a bit of loctite and that has fixed the problem. But that first year of having to basically tighten up 6-8 spokes every single time I rode my bike, was annoying.
  • 4 0
 Sounds like you actually do have regrets. The rim is likely the reason your spokes wouldn't hold tension.
  • 2 0
 @Eatsdirt: well I have them now after reading this press release, haha.
  • 1 1
 Stans rim design is the worst for lateral stiffness, which is why your spokes go slack and loosen. They are the poster child for why you should hire engineers to design things. Notice how DT sticks with the same triangular rim profile for their mountain rims.
  • 2 0
 I hope you guys didn't test the Enve rims in that impact tester of yours or you'd still be picking shards of carbon fibers from your skin.
  • 2 0
 Looking at the spec on Stans site the EX3 rim is 100g heavier than the MK3 rim.
  • 2 0
 So I guess I will end up running a EX3 to replace my rear MK3. Another ding after this mornings ride.
  • 2 2
 I really don't believethat a 511 or a 471 are bending like that , i really don't trust Stan either , for some years they are not doing what they've used to .
  • 1 0
 My lard arse is thankful for these new rims, will definitely be getting a set.
  • 4 0
 Save yourself the trouble and get some Spanks. Much stronger than most rims* and lighter than this new soft.. err Stan's offering.

*I have heard good things about DT Swiss, but I went with Oozy 345s instead.
  • 2 0
 @sacrilege: I used to run Stans Mk3's and they sucked. Cooked so many so switched to Spanks. Recently got on the vibrocore version, blew my mind
  • 3 1
 Oh Snap! I mean: Oh dent!?
  • 1 0
 Sounds to me like they are just trying to be like DT Swiss with a name starting with EX.
  • 2 1
 I didn't smoke hash today.
  • 1 1
 Sounds like a bad day...
  • 1 0
 Are these going to be available in 26" with 36h drilling?
  • 2 0
 Doesn't look like there's a 26 version
  • 2 0
 @cains08: Stan trashed 26 a while ago, I am looking for a spare 26 ZTR Flow rim to replace a broken one (my hunt here:, I have contacted Sabma (distributor of Stan in Belgium), Stan does not produce them anymore...

I bought this pair of good wheels (Hope Pro2 with Stan ZTR Flow rims and Sapim spokes) after having problems with a pair of Easton Haven (24 spokes, straight spokes, special rim, special nipples), after some months fighting to get spare spokes, and the impossibility to get a spare rim for it that I could repair myself.

Now I have some Hope (!) I can repair the real wheel with a decent rim, Hope is still producing all their rims for 26.

#26isnotdead but industry wants to kill it.
  • 1 0
 @zoobab2: I just checked and there seems to be no petition for the bike industry to have 26" back. Perhaps we should start one...
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