The upper linkage is an important component of the Polygon Siskiu D5 bike. It helps to provide a smooth and comfortable ride, and it also helps to improve the bike's handling. If the upper linkage is damaged, it can affect the performance of the bike. The upper linkage is connected to the frame of the bike by a series of bearings. These bearings allow the linkage to move smoothly and efficiently. The upper linkage also has a shock absorber, which helps to absorb bumps and vibrations from the trail

• Increased traction: The upper linkage helps to keep the rear wheel in contact with the ground, even when the bike is going over bumps or obstacles. This can help to improve the bike's traction and prevent it from slipping.
• Reduced fatigue: The upper linkage helps to absorb bumps and vibrations, which can help to reduce fatigue in the rider's arms and legs. This can make it easier to ride for longer periods of time.
• Improved safety: The upper linkage can help to prevent the rider from losing control of the bike, which can help to reduce the risk of accidents.