To measure a hub, you primarily need to determine its width, often referred to as the overlocknut dimension (O.L.D.), using a measuring tool like a ruler or caliper.
Understanding Hub Measurement: Focusing on Width
When measuring a hub, particularly for wheel compatibility, the most common measurement is its width. This measurement determines if the hub will fit correctly into your bike's frame or fork dropouts.
The Width Measurement Process:
Measuring the width involves finding the distance between the outermost points where the hub contacts the frame or fork dropouts. For most modern hubs, this is the distance across the locknuts or end caps.
Tools Needed
- Ruler: A standard ruler can work for a basic measurement.
- Caliper: Digital or dial calipers offer greater precision.
Step-by-Step Guide to Measuring Hub Width
- Remove the Wheel: Take the wheel off the bike frame or fork.
- Ensure Proper Assembly: The hub should be fully assembled with its end caps or locknuts tightened appropriately, as these are the points you'll measure between.
- Position the Tool: Place your ruler or caliper across the hub, ensuring the measuring ends are precisely on the outer faces of the locknuts or end caps on both sides.
- Take the Measurement: Read the measurement displayed on your tool.
Example Measurement from Reference
As demonstrated in the provided reference, measuring the width of a hub can show a dimension like 11 centimeters. Converting this to millimeters, as also shown, gives you 110 millimeters. This measurement confirms the width of the hub being measured.
"And here you can see that it's 11 centimeters which is 110 millimeters. So this hub is 110 millimeters wide. So we've just measured the width of the hub."
Why Hub Width (O.L.D.) Matters
Knowing your hub's width is crucial for:
- Frame/Fork Compatibility: Ensuring the hub matches the dropout spacing of your frame (rear hub) or fork (front hub). Common rear widths include 130mm, 135mm, 142mm, 148mm (Boost), 157mm, etc. Common front widths include 100mm, 110mm (Boost), etc.
- Wheel Building: Selecting the correct hub shell for spokes and rim.
- Buying Replacement Parts: Ensuring new hubs or wheels fit your existing bike.
While other hub dimensions like flange diameter, spoke hole count, and center-to-flange distance are important for wheel building, measuring the overall width is often the primary concern for bike fitment.
