Chainring SAMOX E-bike Narrow wide BCD104 steel black. 40T.

Narrow wide chainring 40 teeth Fits 3/32", 11/128" chains 4-bolt mounting Color: Black BCD/cross bolt hole spacing: 104mm Weight: 170g Measuring bolt hole spacing on chainrings: For 4-bolt models, measure the distance between adjacent holes. For 5-bolt models, primarily use the measurement chart below for reference. Number of bolts on chainring | Distance between two holes | Hole diagonal spacing | mm | inches | (PCD/BCD) 4 | 45.3 mm | 1.78 inch | 64 mm 4 | 56.6 mm | 2.23 inch | 80 mm 4 | 62.2 mm | 2.45 inch | 88 mm 4 | 66.5 mm | 2.62 inch | 94 mm 4 | 67.9 mm | 2.67 inch | 96 mm 4 | 72.1 mm | 2.84 inch | 102 mm 4 | 73.5 mm | 2.90 inch | 104 mm 4 | 84.9 mm | 3.34 inch | 120 mm 5 | 43.5 mm | 1.71 inch | 74 mm 5 | 55.2 mm | 2.18 inch | 94 mm 5 | 64.7 mm | 2.55 inch | 110 mm 5 | 76.4 mm | 3.01 inch | 130 mm 5 | 79.4 mm | 3.12 inch | 135 mm Calculation formula for bolt circle diameter (BCD) based on outer bolt spacing: 4-bolt: Divide the distance between adjacent holes by 0.7071 = bolt circle diameter 5-bolt: Divide the distance between adjacent holes by 0.5878 = bolt circle diameter