Stem FSA OS-99 CSI UDF ST 31.8 AL7075 V14

Stem FSA OS-99 CSI UDF ST 31.8 AL7075 V14

The FSA OS-99 CSI UDF ST stem is a high-end, ultra-lightweight cockpit component designed for performance-focused road cyclists. It combines advanced aluminum construction with carbon aesthetics for optimal stiffness and minimal weight.

The stem is 3D forged and CNC machined from AL2014 aluminum, then finished with a UD carbon weave skin using FSA’s CSI process. This enhances structural rigidity while delivering a premium carbon look.

A 41 mm fork clamp stack height ensures secure and stable mounting. With its extremely low weight, the OS-99 CSI UDF ST is ideal for riders seeking maximum efficiency without compromising control or durability.

• Material: AL2014 alloy with UD carbon skin
• Manufacturing: 3D forged, CNC machined
• Handlebar clamp: Ø31.8 mm
• Fork clamp stack height: 41 mm
• Finish: UD carbon
• Weight: 126 g (100 mm)