The Stan's Flow MK4 is a 29-inch aluminium mountain bike rear wheel designed around a straightforward performance goal - letting the rider do more. Corner harder, send features further, and carry more speed through technical trail sections by giving the wheel the traction, control, and structural properties that modern trail and enduro riding demands. The MK4 is the current generation of Stan's Flow platform, refined from previous iterations with updated hub technology, rim design, and construction to raise the performance ceiling of a proven wheel platform.
The rear wheel is built on 12x148mm Boost spacing with a 6-bolt disc interface and an XDR freehub body - the SRAM standard required for 12-speed Eagle and other XDR-standard cassettes. Confirm your drivetrain uses an XDR freehub interface before purchase. Tubeless tape and Presta valves are included in the box, making tubeless setup straightforward from the moment the wheel arrives.
This listing is for the rear wheel only. The matching Flow MK4 front wheel is available separately.
The rim combines two distinct technologies that Stan's has developed to address the core limitations of standard aluminium wheel construction. BST-Asymmetric is Stan's rim design that combines the BST tubeless bead seat technology - the system that made Stan's famous for easy tubeless inflation - with an asymmetric rim profile. The asymmetric cross-section positions the rim bed off-centre, allowing a more even spoke tension balance between the driveside and non-driveside spokes. More balanced spoke tension across both flanges produces a stronger, more durable wheel build than a centred rim where the driveside spokes typically carry significantly higher tension than the non-driveside.
The 30mm internal width is optimised for tyre widths in the 2.3 to 2.6-inch range - the most common width range for modern trail and enduro tyres on 29-inch wheels. At 30mm internal width the tyre forms a rounder, more supported cross-section at lower tubeless pressures, improving traction and cornering grip in the conditions that trail riding presents.
The rim is built from 6069 aluminium - a higher-grade alloy than the more common 6061 used in many aluminium rims, providing greater strength and durability at a given wall thickness. A welded joint and reinforced spoke bed add structural integrity at the two locations where aluminium rims most commonly show wear and failure over extended use.
The M-Pulse hub is Stan's ultra-low drag magnetic pawl hub system. Standard pawl hubs use spring-loaded pawls that apply constant tension against the drive ring whether the hub is freewheeling or engaged, creating drag during coasting. The M-Pulse magnetic pawl system reduces this drag by using magnetic force to hold the pawls in their retracted position during freewheeling, only engaging them under power. This reduces rolling resistance during coasting - meaningful on trail sections where carrying speed without pedalling is the goal.
The 1.66-degree engagement angle is the measurement of how much the pedals must rotate before the hub fully engages and begins transferring power to the rear wheel. At 1.66 degrees the engagement is fast - providing quick drivetrain response when the rider begins pedalling again after a corner or technical section. Enduro bearings with double-row freehub bearing construction provide increased bearing contact area and load capacity suited to the lateral forces and impact loads of aggressive trail and enduro riding.
J-bend lacing across the matched wheelset uses a single shared spoke length for both wheels, simplifying servicing - a practical detail that means any bike shop or home mechanic can source replacement spokes without needing to know two different spoke lengths for the same wheelset.
This version uses an XDR freehub body, compatible with SRAM's 12-speed Eagle and other XDR-standard cassettes. XDR is not compatible with standard Shimano HG cassettes - confirm your drivetrain uses an XDR freehub interface before purchase.
BST-Asymmetric combines Stan's tubeless bead seat technology with an asymmetric rim profile that positions the rim bed off-centre. This allows more even spoke tension balance between driveside and non-driveside spokes, producing a stronger and more durable wheel build than a centred rim where tension imbalance between the two sides reduces overall structural integrity.
The 30mm internal width is optimised for tyre widths in the 2.3 to 2.6-inch range - the most common range for modern trail and enduro 29-inch tyres. This internal width allows the tyre to form a rounder cross-section at lower tubeless pressures for improved traction and cornering grip.
Standard pawl hubs apply constant spring tension against the drive ring during freewheeling, creating drag even when not pedalling. The M-Pulse system uses magnetic force to hold the pawls retracted during freewheeling, only engaging them under pedalling power. This reduces rolling resistance during coasting - meaningful on trail sections where carrying speed without pedalling is the goal.
Yes. Tubeless tape and Presta valves are included in the box, making tubeless setup straightforward from the moment the wheel arrives. Tubeless tyres and sealant must be sourced separately.
| Rear Axle | 12mm Thru x 148mm |
| Rim Width (Internal) | 30 |
| Cassette Body Type | SRAM XDR |
| Valve | Presta |
| Color | Black |
| Wheel Size | 29" |
| Defined Color | Black |
| ISO Diameter | 622 / Road / 29" |
| Tire Type | Tubeless Ready |
| Rim Material | Alloy |
| Hub/Brake Compatibility | 6-Bolt Disc |
| Axle Configuration | 12 X 148Mm |
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