Stan's No Tubes Flow MK4 Disc Brake Rim
The Stan's NoTubes Flow MK4 is the enduro rim from the company that made tubeless mainstream: 30mm inside for 2.3 to 2.6in tires, 6069 alloy with a welded joint, an asymmetric profile with offset spoke drilling and a reinforced spoke bed, and the BST hookless bead that seats a tubeless tire with a floor pump and holds it at the low pressures enduro riding wants. Stan's builds its own Flow wheels to 105 kgf and allows up to 125, which tells you how strong the spoke bed is.
This page covers the Stan's No Tubes Flow MK4 Disc Brake Rim in 29in, 27.5in, 26in. The Flow MK4 comes from us only as a finished wheel: pick the hub, spokes and nipples, and we lace, tension and true it by hand in Georgia before it ships.
Design and construction
BST, Bead Socket Technology, is Stan's low, hookless bead wall: the tire bead sits in a socket rather than under a hook, which is why a tubeless tire seats so easily on a Stan's rim and stays put at 18 psi. The low wall also gives the tire a larger effective volume and makes pinch flats less likely because there is no sharp hook to cut the casing. The MK4 profile adds an offset spoke bed, which brings drive-side and non-drive-side tension close to equal on a Boost rear, and a reinforced spoke bed that takes the higher tension.
The Flow MK4 is 6069 alloy, stronger than 6061, welded rather than sleeved, with a three-year warranty and a one-year crash-replacement program. Standard nipples, J-bend spokes, disc only.
How it rides
A Flow MK4 wheel is a wide, stable enduro wheel that stays true. The 30mm bed and BST wall let you run a 2.5in tire soft for grip, the welded 6069 rim takes rock strikes, and the offset rear holds tension through a season of hard riding. It is not the lightest 30mm alloy rim; it is one of the toughest, and the tubeless setup is the easiest in the business.
For trail riding the Arch MK4 is lighter; for cross-country and gravel the Crest MK4; for park and downhill the Flow EX3 is stronger still. For enduro and aggressive trail, the Flow MK4 is the Stan's rim we recommend.
Specifications
| Wheel size | 29in, 27.5in, 26in |
|---|---|
| ERD | 595 (29in), 561 (27.5in), 536 (26in) |
| Inner width | 30 mm |
| Depth | 18.9 mm |
| Drillings | 28h, 32h |
| Weight | 521g (700c/29in), 487g (650b/27.5in), 466g (26in) |
| Material | Aluminum |
| Tire type | clincher tubeless compatible |
| Brake | Disc |
| Spoke bed | Offset 3 mm |
| Nipples | External |
| Finishes | black |
About this listing
Version notes. 29in, 27.5in, 26in, 28h, 32h, about 521g, 30mm inside, 18.9mm deep, disc. The other sizes and brake versions of the Flow MK4 have their own listings; this page is for this one.
The disc version of the Flow MK4 has no brake track, so the sidewall is a plain extrusion that saves a little weight and never wears; it is the one to choose for any disc-brake frame. The rim-brake version, listed separately, has a machined sidewall.
Sizes, fit and compatibility
The Stan's No Tubes Flow MK4 Disc Brake Rim comes in 29in, 27.5in, 26in and 28h, 32h drilling. It is a disc-brake rim. We build the Flow MK4 on DT Swiss 350 and 240, Industry Nine 1/1 and Hydra 2, Hope Pro 5, Onyx Vesper, Chris King MTB and Bitex BX 211 hubs, usually with Sapim Race, D-Light or CX-Sprint spokes or DT Competition and brass nipples.
Tire range on the Flow MK4 is 2.3 to 2.6in with tubeless-ready tires on the BST bead. Pick your bike type and weight in the configurator and it recommends a spoke count and lacing pattern.
Build a wheel around it
Offered for tandem and e-bike, mountain bike, MTB single-speed and fat bike builds in our Custom Wheel Program. Start with the Stans No Tubes Flow Mk4 Disc Brake Rim and the configurator pins it for you, then checks each choice you make against it.
Spoke head is decided by the hub, not the rim: this rim builds equally well with J-bend or straight-pull spokes, and the configurator only offers the spokes that match the hub you pick.
Testing, standards and warranty at Stan's No Tubes
Stan's NoTubes of Big Flats, New York builds its rims around patented Bead Socket Technology (BST), a low-profile sidewall that secures the tire bead rather than the sidewall, which Stan's states gives an airtight seal and lighter, stronger rims. MK4 and EX3 aluminum rims are welded 6069 alloy with a reinforced spoke bed, which Stan's states is "10-15% stronger" than 6061; S2 rims are sleeved 6061 with stainless eyelets.
Published limits: max spoke tension Crest MK4 115 kgf (1130 N), Flow EX3 125 kgf (1225 N), Flow S2 130 kgf (1275 N), Crest CB7 and Valor carbon 105 kgf. Max pressure depends on tire width, for example Crest MK4 55 psi with 40 mm and 39 psi with 2.3"; Flow EX3 39 psi with 2.3" and 34 psi with 2.6"; Grail CB7 85 psi. No rider weight limit is published.
Warranty (original owner): CB7/SRD carbon 7 years with registration plus lifetime crash replacement at 50% off MSRP; MK4/EX3 aluminum 3 years; S1, S2, MK3, D and K 2 years; all aluminum rims 1-year crash replacement at 50% off.
Stan's No Tubes's videos
Certifications
- Patent — Stan's states Bead Socket Technology (BST) is patented (source)
Sources on Stan's No Tubes's site:
- Bead Socket Technology (BST) - Stan's
- Warranty Information - Stan's NoTubes
- About Us - Stan's
- Crest MK4 Rim - Stan's
- Flow EX3 Rim - Stan's
Everything in this section is published by Stan's No Tubes. ProWheelBuilder is the wheel builder, not the tester, and the rim reaches us as the maker ships it.
Building it at ProWheelBuilder
Stan's NoTubes makes the Flow MK4; ProWheelBuilder is an independent wheel builder in Georgia, not the manufacturer. Offset rims need the spoke lengths calculated per side, which we do from the rim's measured ERD and offset; every Flow wheel is tensioned in stages with a gauge within Stan's published range, stress-relieved and trued before it ships. Stan's tape and a valve are fitted on request.
Only compatible hubs and spokes appear in the configurator, impossible combinations are struck through rather than hidden, and the price is live.
Warranty
Stan's No Tubes's warranty. Stan's covers aluminum rims for two years against manufacturing defects. Registered carbon wheelsets carry seven years of warranty cover plus lifetime crash replacement, and registration must be completed before a wheelset claim can be made. Crash damage, abuse and normal wear are not warranty items.
ProWheelBuilder. Any wheel we build on this part carries ProWheelBuilder's one-year warranty in addition to the manufacturer's. Broken spokes are replaced for a year whatever the cause, and all wheel-side labor is included - truing, re-tensioning, rebuilding. Where the maker covers a failed rim or hub we handle that claim for you; where they decline, an eligible replacement comes at 25% off current retail. The customer covers shipping in both directions. Components supplied by the customer are not covered.
Full terms are on our Policies & Warranty page.
Flow MK4 Disc Brake Rim questions
What tire width suits this rim?
At 30mm inside this is a trail width, sized around 2.1 to 2.4in tires. That is wide enough to stop a modern trail casing rolling under you in a corner without pushing the tread so flat that it wears down the middle.
Flow MK4 or Flow EX3?
MK4 for enduro and aggressive trail; EX3 for park and downhill, where its Tiebeam triple-cavity profile resists bigger impacts.
What spoke tension does the Flow MK4 take?
Stan's builds to 105 kgf and allows up to 125 kgf; we build within that range with a gauge.
Is the Flow MK4 hookless?
Yes. BST is a low hookless bead; use tubeless-ready tires and stay under the pressure printed on the rim, which is far above enduro pressures anyway.
What is the Flow MK4 warranty?
Three years on the rim, with a one-year crash-replacement program from Stan's.
Is it tubeless-ready?
Yes. Stan's No Tubes lists the Flow MK4 Disc Brake Rim as clincher tubeless compatible; we tape and fit a valve when you choose the tubeless option.
Which spoke count should I choose?
It depends on your weight, terrain and the hub, not the rim alone. The configurator recommends a count from your bike type and rider weight, within the drillings this rim is made in.
Not sure? Text or leave a voicemail on 470-253-0929 or email info@prowheelbuilder.com — you will be talking to the people who build the wheels.
