To convert the diameter of the bike wheel from inches to millimeters, you can use the conversion factor of 1 inch = 25.4 millimeters.
Given that the diameter of the bike wheel is 26 inches, you can calculate the diameter in millimeters as follows:
\[ \text{Diameter in mm} = \text{Diameter in inches} \times \text{Conversion factor} \]
\[ \text{Diameter in mm} = 26 , \text{inches} \times 25.4 , \text{mm/inch} \]
\[ \text{Diameter in mm} = 660.4 , \text{mm} \]
So, the diameter of the bike wheel in millimeters is 660.4 mm.