What is the diameter of a motorcycle handlebar?
2 Answers
For common motorcycles, the inner diameter of the handlebar steel tube is generally between 17-18 millimeters. Function of motorcycle handlebars: The handlebar is integrated with the front suspension system via bolts, serving to maintain driving balance, steer the vehicle, and thus change the direction of travel. The right side of the handlebar is equipped with the right brake lever housing, front brake lever, front brake light switch, throttle controller, and headlight switch. The left side of the handlebar is fitted with the left brake lever housing, clutch lever, lighting switch, dimmer switch, horn switch, and other components for controlling the motorcycle. However, on JH125 and JH145 motorcycles, the headlight switch is located on the left brake lever. Function of motorcycle throttle grip: The throttle grip, also known as the throttle control handle or simply the throttle, is positioned on the right side of the handlebar tube. It is mounted over the handlebar tube and inside the right brake lever housing, connected to the carburetor's throttle valve via the throttle cable (throttle wire, throttle pull wire, throttle tension wire). Rotating the throttle grip raises or lowers the plunger inside the carburetor, thereby controlling the throttle, adjusting the amount of combustible mixture entering the cylinder, changing the engine's speed, and consequently altering the motorcycle's travel speed.
Motorcycle handlebar diameters actually don't have a unified standard, it mainly depends on the bike model and design. Street bikes and sports bikes commonly use 22mm (7/8 inch) diameter - like my Kawasaki Ninja has this size. Off-road handlebars tend to be thicker, around 25mm, because they need to withstand impact forces during jumps. When modifying handlebars, pay special attention: cruisers like Harley typically have 1-inch (25.4mm) diameter at the central mounting point, but the grip area may taper down to 22mm. Last month I helped measure my friend's BMW R1250GS - 24mm at the center tapering down to 20mm at the ends, this graduated design makes it easier to install handguards. Always use calipers to measure the mounting points - even 1mm deviation may cause installation failure.
