Stan's No Tubes Flow EX3 Disc Brake Rim
The Stan's NoTubes Flow EX3 is the gravity rim in Stan's range, built for downhill, bike park and hard enduro. The Flow EX3 has a 29mm inner width for 2.3 to 2.6in tires, bead-blasted 6069 alloy, the BST hookless tubeless bead, and Stan's Tiebeam profile: a triple-cavity section with an inner bridge that resists impacts and keeps the rim holding air and shape after hits that would flatten a conventional rim.
This page covers the Stan's No Tubes Flow EX3 Disc Brake Rim in 29in, 27.5in. The Flow EX3 is not sold bare. You choose the hub and the rest of the build in the configurator, and it ships from our shop in Georgia laced, tensioned and trued by hand.
Design and construction
Tiebeam is what sets the Flow EX3 apart from every other Flow. A conventional double-wall rim is a single box section; the EX3 divides its section into three cavities with an internal bridge, which stiffens the bead walls against square-edged hits and stops a dent in the outer wall from becoming a leak. The 6069 alloy is stronger than 6061 and bead-blasted for a matte finish that hides scratches. The BST bead seats a tubeless tire with a floor pump and holds it at the very low pressures downhill riders run. Standard nipples, J-bend spokes, disc only, three-year warranty with one-year crash replacement.
How it rides
A Flow EX3 wheel is built to be pointed downhill, and the Flow EX3 is the rim Stan's puts under its own downhill wheels. The Tiebeam section takes flat landings and rock gardens that fold ordinary alloy rims, the BST bead keeps a 2.5in downhill tire seated at 18 psi, and the wheel holds tension run after run. It is heavier than the Flow MK4, which is the price of the strength.
For enduro and aggressive trail the Flow MK4 is lighter; for downhill, park and e-MTBs, the Flow EX3 is the Stan's rim we recommend.
Specifications
| Wheel size | 29in, 27.5in |
|---|---|
| ERD | 602 (29in), 564 (27.5in) |
| Inner width | 29 mm |
| Depth | 17.9 mm |
| Drillings | 32h |
| Weight | 618g (700c/29in), 580g (650b/27.5in) |
| Material | Aluminum |
| Tire type | clincher tubeless compatible |
| Brake | Disc |
| Spoke bed | 0 |
| Nipples | External |
| Finishes | black |
This listing
This is the 29in, 27.5in listing of the Flow EX3, 32h, about 618g, 29mm inside, 17.9mm deep, disc. Pick the size that matches your frame; the profile and construction are the same across the range.
The disc version of the Flow EX3 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 EX3 Disc Brake Rim comes in 29in, 27.5in and 32h drilling. It is a disc-brake rim. We build the Flow EX3 gravity rim on DT Swiss 350, Industry Nine Hydra 2, Hope Pro 5, Onyx Classic and Chris King MTB hubs, usually with Sapim Race, Strong or CX-Sprint spokes or DT Competition and Alpine III, and brass nipples.
Tire range on the Stan's Flow EX3 is 2.3 to 2.6in with tubeless-ready tires on the BST bead. Pick downhill or e-bike as your bike type in the configurator and it recommends a spoke count and lacing pattern.
Put it in a custom wheel
Build a custom wheel around the Stans No Tubes Flow Ex3 Disc Brake Rim — the link drops you into our Custom Wheel Program with this rim pinned, ready for you to choose the rest. It is set up for tandem and e-bike, mountain bike, MTB single-speed and fat bike builds.
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.
What Stan's No Tubes says about testing
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.
Testing: Pinkbike's 2016 factory tour documented carbon-rim deflection testing under a variable load measured by a load cell, a drop tower for impact testing with high-speed imaging, and electronic QC of built-wheel trueness and spoke tension. For the Flow EX3, Stan's describes "an incredibly brutal testing procedure based on impact forces we studied from the Mont-Sainte-Anne World Cup DH course" using a weighted wedge dropped onto an inflated tire and rim. No joule, cycle, ISO 4210 or UCI figures are published.
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.
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
The figures, certificates and media above are Stan's No Tubes's own. ProWheelBuilder does not run these tests; our part is the wheel we build on the rim.
Building it at ProWheelBuilder
Stan's NoTubes makes the Flow EX3; ProWheelBuilder is an independent wheel builder in Georgia, not the manufacturer. We calculate Flow EX3 spoke lengths from the rim's measured ERD and offset, tension every Flow EX3 wheel in stages with a gauge within Stan's published range, stress-relieve it and true it before it ships. Stan's tape and a valve are fitted on request.
In the configurator you will only see parts that fit this drilling; combinations that are not made are struck through, and the price updates as you pick.
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. If we lace this into a wheel for you, that wheel also carries ProWheelBuilder's own one-year warranty, which covers broken spokes regardless of cause and all wheel-related labor, including truing and rebuilding, for a year from purchase. Where a rim or hub is covered by its maker, we make the manufacturer's claim for you and coordinate it; where it is not, we offer an eligible replacement rim or hub at 25% off current retail. Shipping to and from us is the customer's. This cover does not extend to wheels built from components you supply yourself.
Full terms are on our Policies & Warranty page.
Flow EX3 Disc Brake Rim questions
What tire width suits this rim?
At 29mm 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.
What is Tiebeam?
Stan's triple-cavity rim section with an internal bridge, which gives the Flow EX3 its resistance to impacts and keeps the rim holding air and shape after hits that would dent a conventional rim.
Flow EX3 or Flow MK4?
EX3 for downhill, park and e-MTBs; MK4 for enduro and aggressive trail, where it is lighter and offset.
Is the Flow EX3 hookless?
Yes. BST is a low hookless bead; use tubeless-ready tires.
Is the Flow EX3 e-bike rated?
Yes. It is one of the alloy rims we recommend for e-MTBs, with e-bike-rated spokes.
Is it tubeless-ready?
Yes. Stan's No Tubes lists the Flow EX3 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.
