How to Measure Hub Flange Distance and Understand Its Impact
Hub flange distance is one of the most important dimensions in wheel building. It affects spoke angle, lateral stiffness, dish, and overall wheel strength. Measuring it correctly ensures accurate spoke length calculations and helps you understand how a hub will perform once built into a wheel. This guide explains how to measure hub flange distance using simple tools and why it matters for both road and gravel wheelsets.
To measure the flange distance, begin by removing the axle end caps to access the hub’s full width. Place the hub on a flat, stable surface. Using a digital caliper, measure the overall hub width, also known as OLD (Over Locknut Distance). Then measure from the left hub flange to the center of the hub, and from the right hub flange to the center. Many builders calculate center-to-flange distance by subtracting half the hub width from each flange measurement.
If your caliper is not long enough to span the hub's full width, you can use a ruler combined with calipers to measure each flange from the outer surface inward. Digital tools provide the most accuracy, especially when building high-tension carbon wheelsets where spoke length differences as small as 1 mm can affect tension balance.
Understanding flange distance helps you predict wheel stiffness. A wider flange spacing on the rear hub improves lateral stiffness and distributes spoke tension more evenly. On the front hub, wider spacing increases stability and makes the wheel more resistant to side loads—important for disc brake wheels that handle braking torque. However, wider flange spacing also increases dish on the rear wheel, especially when accommodating an 11-speed or 12-speed cassette. More dish means the drive-side spokes must carry higher tension, making the wheel slightly less durable overall.
The flange distance also affects spoke bracing angle. A larger bracing angle provides better resistance to flex, which improves sprinting stiffness and cornering performance. Gravel wheels with large flange spacing tend to feel more stable under heavy loads and rough terrain. Conversely, narrow flange spacing can reduce stiffness but may allow for more aerodynamic hub designs.
When entering spoke length calculators, accuracy in flange distance is essential. Small measurement errors can produce incorrect spoke lengths or uneven tension. Always measure both flanges separately—even if the hub appears symmetrical—because many disc hubs have offset flanges to balance rotor spacing.
Below is a table you can copy directly into Word for recording measurements during wheel building:
Hub Flange Distance Measurement Table
|
Measurement Item |
Value (mm) |
Notes |
|
Total hub width (OLD) |
|
e.g., 100mm / 142mm / 148mm |
|
Left flange to outer edge |
|
Measure with a caliper |
|
Right flange to outer edge |
|
Measure with a caliper |
|
Calculated the center of the hub |
|
OLD ÷ 2 |
|
Left center-to-flange distance |
|
Left outer − center |
|
Right center-to-flange distance |
|
Right outer − center |
|
Hub type |
|
Road / Gravel / MTB |
|
Disk or rim brake |
|
Affects flange offset |
|
Notes on symmetry |
Symmetrical / Offset |
|