FSA OS99 CSI stem

FSA K-FORCE OS-99 CSI Stem – ±6°, 60–130 mm

Brand: FSA
Series: K-FORCE
Type: Stem
Discipline: Road
Technology: CSI (Carbon Structural Integration)
Material: AL2014 alloy + UD carbon
Angle: ±6°
Fork Clamp Stack Height: 41 mm
Weight: 126 g

The FSA K-FORCE OS-99 CSI stem combines a 3D-forged and CNC-machined AL2014 alloy structure with carbon using FSA's CSI (Carbon Structural Integration) technology. This process permanently bonds carbon to alloy to create a true hybrid construction, combining the characteristics of both materials.

The OS-99 design is further optimized with a sculpted 4-bolt AL2014 alloy/carbon faceplate and titanium hardware, helping reduce weight while maintaining a rigid and precise connection between the handlebar and steerer tube.

Key Features

• 3D-forged and CNC-machined from AL2014 alloy

• CSI (Carbon Structural Integration) technology

• Permanent carbon-to-alloy bonded construction

• UD carbon finish

• Sculpted 4-bolt alloy/carbon faceplate

• Titanium hardware

• 41 mm fork clamp stack height

• ±6° angle

• Available in 60–130 mm lengths

• Lightweight construction

• Designed for road cycling

Technical Specifications

References

In Practice

The K-FORCE OS-99 CSI is designed for road bikes where low weight, a rigid stem-to-handlebar connection and the combination of alloy and carbon construction are important considerations. The ±6° angle and eight available lengths provide flexibility when fine-tuning the riding position.