Ritchey is one of several component companies that updates their top of the line product and rather than retiring the previous top shelf part, merely pushes it down the line. The Ritchey Pro OS Stem is basically the old WCS stem, minus the world trademark championship stripes, and without the polishing of the naked aluminum.

Some things don't change at all -- the steerer clamp is 1 1/8" and has an angled slot for better gripping lightweight steerers without pinching. The bolts are still stainless steel. The main difference is in the front of the stem. The four bolts hold two separate narrow plates that provide a wide clamping area to hold the handlebar securely. Like the WCS stem, more than half the bar sits on the stem itself so the two-part faceplate is responsible for less stress and is even less likely to break. Stainless steel bolts hold the plates to the stem. A nearly hidden design flourish is a lip on the stem where the faceplates hook onto the stem. This is a genius little bit of safety -- it weighs almost nothing, but holds the pieces in place if there's ever a partial failure.

The Ritchey Pro OS stem is designed for 31.8mm handlebars and 1 1/8" steerer tubes. The stem angle is +/-6 degrees (aka 84/96 degrees). The stem is made from 6060-T6 aluminum. The bolts are all stainless steel. 150g (110mm.)