Chainline is measured from the centerline of the frame to the center of the chain. You can measure the front chainline directly with a simple ruler. Simply hold the ruler against the seat tube or down tube and measure the distance from the middle of the seat tube to the middle of the chainring teeth.
How to Measure Chainline?
Chainline is an important feature of a bicycle that helps to determine the efficiency of the bike. It is the line of the chain as it runs through the bicycle’s drivetrain and can affect shifting performance, pedaling efficiency, and overall bike performance. Therefore, it is important to make sure that the chainline is correctly set up when you build or maintain a bicycle.
The first step to measuring the chainline is to determine the number of teeth on the chainrings. This is important because the chainline will be different depending on the number of teeth on the chainrings. For example, a bike with a 50-tooth large chainring and a 34-tooth small chainring will have a different chainline than a bike with a 44-tooth large chainring and a 30-tooth small chainring.
Once you have determined the number of teeth on the chainrings, the next step is to measure the distance between the outermost points of the chainrings. This is done by placing a ruler or measuring tape between the two points and measuring the distance. This measurement is referred to as the chainline.
To ensure that the chainline is correct, it is important to also measure the distance between the center