The CX403 uses a unique monocoque carbon construction shared only with the CX400 and CX400L. The upper wraps around an integrated carbon outsole and heel counter, creating additional fixed internal volume compared to traditional Race Last models where the sole is bonded beneath the upper. Because of this construction, the CX403 may feel slightly roomier than models such as the CX333 in the same size and width. The added volume comes from the carbon shell rather than the last shape itself.
Despite this additional space, the integrated carbon heel and sole structure create exceptional rearfoot stability and one of the stiffest, most supportive performance experiences in the collection.
Riders coming from softer uppers may notice a more structured feel across the heel and arch. If you are between sizes or prefer additional room, consider sizing up 0.5–1 size.