How to Measure Press Fit Bottom Bracket
The press fit bottom bracket (PFBB) has become a popular choice for many cyclists due to its ease of installation and compatibility with various frame designs. However, accurately measuring a press fit bottom bracket is crucial to ensure proper fit and functionality. In this article, we will guide you through the process of measuring a press fit bottom bracket to help you make an informed decision when purchasing or installing one.
First and foremost, it is essential to understand the different types of press fit bottom brackets available. The most common types are PF30, PF31.6, PF38, and BBright. Each type has a unique shell diameter and spacing, which must be measured to ensure compatibility with your frame.
To measure a press fit bottom bracket, follow these steps:
1. Identify the Frame Type: Determine whether your frame is PF30, PF31.6, PF38, or BBright. This information can usually be found in the frame’s specifications or by consulting the manufacturer.
2. Measure the Frame Shell Diameter: Using a caliper, measure the inner diameter of the bottom bracket shell. For PF30, the diameter should be 30mm; for PF31.6, it should be 31.6mm; for PF38, it should be 38mm; and for BBright, it should be 86.8mm.
3. Measure the Frame Shell Width: The width of the bottom bracket shell is also crucial for proper fit. For PF30 and PF31.6, the standard width is 68mm, while for PF38, it is 73mm. BBright frames typically have a width of 86.8mm.
4. Check the Bottom Bracket Spacing: The spacing refers to the distance between the bottom bracket shell’s centerline and the centerline of the crank spindle. This measurement is important for ensuring that the cranks are aligned correctly. The standard spacing for PF30 and PF31.6 is 113mm, while for PF38, it is 100mm. BBright frames usually have a spacing of 110mm.
5. Compare Measurements: Once you have gathered all the necessary measurements, compare them to the specifications of the press fit bottom bracket you plan to purchase. Ensure that the shell diameter, width, and spacing match your frame’s dimensions.
6. Consider the Crank Arm Length: The length of your crank arms can also affect the bottom bracket fit. Make sure the bottom bracket you choose is compatible with your crank arm length to avoid any issues with installation or performance.
By following these steps, you can accurately measure a press fit bottom bracket and ensure that it is the right fit for your frame. This will help you avoid costly mistakes and ensure that your bike performs optimally on the road.
