The new Sigma X is MUCH lighter and MUCH stiffer than its predecessor, owing to all-carbon construction. Now you can have an aero advantage without a weight penalty.
The aero features from Sigma X were borrowed from our brand new Alpha X aerobar platform. The aero-matched spacers are identical, as is the wedge-style steerer clamp, and the removable centerpull cable stop. The Sigma X is basically the Alpha X, minus the bar.
The new Sigma X eliminates the traditional drawback of integrated stems, which is the requirement of trimming your fork's steerer tube. The Sigma X cable cover stops just in front of the steerer tube, allowing you to maintain clean cable routing and also preserve the ability to change position in the future.
The two bolts on top that affix the Sigma X cable cover --- those are spaced at 63mm for a water bottle cage or storage box. So you get a clean mounting option, no zip ties required.