ZEB Ult B1 CSU

The crown steerer upper assembly is the structural core of a RockShox ZEB Ultimate B1+ fork from the 2027 model year onward. It combines the steerer tube, the crown and both upper tubes as a single assembly, and it is replaced as one part after a crash or once creaking shows that the crown to upper tube joint has moved.

This assembly uses the ButterWagon Tech uppers that RockShox lists for the LinearXL generation of the ZEB Ultimate. The steerer is a 1.5 inch tapered aluminum unit, and the crown accepts both 27.5 and 29 inch lower leg assemblies, so wheel size follows the lowers. Fork offset is fixed by this part and cannot be altered afterwards.

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