The Thomson X4 31.8 Stem (Black) is a X4 stem with 31.8mm clamp diameter in black anodized aluminum CNC-machined by Thomson Bike Products at their Macon, Georgia facility. Thomson uses 7000-series aluminum and tight machining tolerances that have made the brand the de facto specification for bicycle stems and seatposts on premium custom bikes for over two decades.
Use it as a permanent upgrade or replacement for OEM stems and seatposts where you want better materials, tighter tolerances, and lifetime durability. Thomson is the brand framebuilders specify by name and the reason a quality stem outlasts the frame it’s mounted on.
Thomson Bike Products has been CNC-machining bicycle components in Macon, Georgia since 1996. Every Thomson stem and seatpost is American-made from US-sourced 7000-series aluminum and built for life.
