Rockshox 38MM CSU Fork Upper Tube What the Fork?!A crashed or scored upper tube does not mean you need to buy a new fork. The 38mm CSU assembly is the structural backbone of Rock Shox's big-stanchion lineup, covering platforms like the ZEB and Lyrik that run the 38mm chassis. Replacing this assembly restores your fork to factory geometry and stiffness without touching the damper or air spring internals you have already dialed in. 38mm stanchion diameter matches the chassis spec of Rock Shox's long-travel single-crown platforms, restoring full lateral and torsional rigidity CSU assembly design integrates the crown, steerer, and upper tubes as a single precision unit so factory alignment is maintained when you torque everything back down Direct OEM replacement lets you keep your existing damper, air spring, and lower leg hardware, so you rebuild around known-good components rather than starting over Compatibility verify your specific fork model and year against the SKU before ordering, as travel length and offset vary across ZEB, Lyrik, and other 38mm platforms | Rockshox | 38Mm Csu Fork Upper Tube | Black | Right