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Stan's Introduces New MK4 and S2 Rims and Wheels

New Wider, Asymmetric Rims and All-New Hubs
Almost 20 years after Stan Koziatek created his first tubeless-ready rims, Stan’s NoTubes is proud to introduce the new Crest, Arch, and Flow MK4 and S2 series aluminum rims and wheelsets. Full information is available here.

• June 30th 2021

MK4 Rims and Wheelsets 

Building upon their experience making asymmetric carbon rims that incorporate their patented Bead Socket Technology (BST), Stan’s developed the MK4s, their first asymmetric aluminum rims.

The BST-Asymmetric design allows for an improved bracing angle and nearly equal spoke tension balance, while also maintaining the easy inflation and reliable airtight seal that have made Stan’s the leader in tubeless rim design.

The new MK4 series rims are available in three updated widths. Each Crest, Arch, and Flow model has its own purpose-built, wider rim shape and spoke hole offset.


Stan's dedication to tubeless performance led to a total rethink of asymmetric rim design and resulted in wheels that are stronger overall than previous versions. In creating the new MK4s, Stan's addressed the issues that most traditional asymmetric wheel designs have, such as being more difficult to inflate, being more prone to air loss due to unequal bead retention, and being more likely to be dented by impacts. As a result, the new MK4 design gives balanced pressure along the drive and non-drive-side tire beads and consistent impact resistance on both sides of each rim.

"Crest, Arch, and Flow MK4 rims are made of 6069 aluminum with a welded seam, have a reinforced spoke bed and walls, and feature a matte-blasted finish." 

rim line up

rim profile


Built for gravel and cross country riding, Crest MK4 rims have an internal width of 25mm with a spoke hole offset of 1.5mm and are optimized for 40mm gravel tires up to 2.3” mountain tires. Offered in 20”, 24”, 26”, 27.5”, and 29” versions, the Crest MK4 rim weighs 374g for the 27.5” version and 399g for the 29” version.

Arch MK4 rims are the most versatile of all Stan’s rims and are ideal for a wide range of trail riding. They have an internal width of 28mm for 2.2-2.5” tires and an offset of 2.5mm. Available in 24”, 26”, 27.5”, and 29”, the 27.5” Arch MK4 rim weighs 451g, while the 29” version weighs 481g.

The legendary Flow rim has earned Downhill World Cup and Enduro World Series wins and is a favorite among gravity and trail riders everywhere. With emphasis on strength and durability, Flow MK4 rims have an internal width of 30mm for 2.3-2.6” tires. Available in 26”, 27.5”, and 29” versions, the Flow MK4 rim weighs 487g in 27.5” and 521g in 29”.


MK4 complete wheelsets will be available in late 2021 and will feature an entirely new M-Pulse hub design that will be shared with all Stan’s high-performance aluminum and carbon wheels.

S2 Rims and Wheelsets

Like the MK4s, Stan’s S2 rims have also increased in width, but they are manufactured with 6061 aluminum using a durable sleeved joint and stainless steel rim eyelets, and they rely on Stan’s proven conventional symmetrical Bead Socket Technology for easy inflation.

S2 rims come in the same widths and are for the same recommended tire sizes as the MK4 rims.

Well suited for eBikes, S2 wheels are built with Stan’s all-new E-sync hubs to handle additional weight and drivetrain stress; they have a 47% increase in max torque load capacity over Stan’s previous Neo hubs. The new E-sync hub has reinforced pawls that distribute stress away from bearings, Chromoly axles, and Enduro brand bearings, including a double row bearing in the freehub to maximize durability.


E-sync hubs provide fast 8.18º engagement, with all pawls engaging simultaneously to ensure reliable engagement under high loads. E-sync’s endcaps and freehubs are backward-compatible with Stan’s previous Neo hubs.

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s2 profile.jpg