This significantly enhances surface hardness and overall toughness, effectively resisting tooth deformation under tension. And the 17 tooth front sprocket has the maximum potential for maximum speed and lower engine speed during cruising, and performs well in highway driving and fuel economy Size: Model: 428-13T Sprocket; Spacing Between The Mounting Holes: 30mm/1.2"; Inner Diameter: 17mm/ 0.67"; Gear Inner Diameter: 14mm/0.55"; Thickness: 7mm/0.28" Note: If you hear the squeaking sound of the chain while riding at low speed, or feel the vibration or hear the clicking sound when rolling the bike forward or sliding to stop. Anyway, you need to check your front sprocket. When this specific component begins to malfunction, it is best to replace it immediately