This carbon fibre bicycle handlebar stem is built for durability and long service life, having undergone extensive life and strength testing to ensure reliability. Key features - Material: carbon fibre for light weight and strength - Clamp diameter: 31.8 mm; steerer tube diameter: 28.6 mm (1-1/8 inch) - Length options: 70, 80, 90, 100, 110, 120, 130 mm - Angles: 6 degrees or 17 degrees - Model choice: please select the right model to meet your requirements Downward angle option - Provides a lower handlebar position to reduce wind resistance and increase speed Upward adjustment option - Raises the handlebar position to improve riding comfort and enhance steering control Compatibility and fit - Compatible with standard 1-1/8 inch steerers and 31.8 mm clamp, suitable for common road bike setups Use scenarios - Road performance and time trials: choose the downward angle for an aero advantage and faster riding - Endurance rides and long-distance cycling: taller, raised options for a comfortable posture and easier control - City commuting or mixed terrain: easily adjust to a comfortable height for better maneuverability and steering feel