The tool sizing listed below is a general guide, but it is possible that the head of a particular bolt on your bike may vary, requiring a different tool (e.g., a 4 mm Allen wrench instead of a 5 mm Allen wrench). If so, use whatever tool fits the bolt head. Such differences will not affect the recommended torque for that piece of hardware. If you are installing accessories from Rad Power Bikes, any necessary instructions, important safety information, and torque specifications will come with your accessory. You can find more detailed information in the RadCity 5 Plus Owners Manual.