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How to Measure Stems

The below diagram shows the common ways to measure a stem. Conflicting systems of measurement may cause some confusion over the terms stem length and stem angle. In the QBP catalog, stem length = extension and stem angle = angle B.

• Extension (mm): The actual length of the stem from the center of the steering bore to the center of the handlebar clamp. This is how QBP measures stem length.
• Reach (mm): The effective length of the stem measured from the centerpoint of the steering bore to the center of the handlebar clamp without accounting for rise. On stems with built-in rise this measurement will be made along an imaginary line (as seen in the diagram).
• Angle (°): The angle of the stem extension relative to one of two different starting points:
  • Angle A: Measured from an imaginary line perpendicular to the steering axis to the center of the stem extension.
  • Angle B: Measured from the center of the actual steering axis to the center of the stem extension. This is how QBP measures stem angle.
  A simple way to look at this difference is the following: Angle B = Angle A + 90°. For example, if a manufacturer advertises a 7° angle using Angle A, QBP would describe this as 97°.
• Rise (mm): The effective height gained as a function of the stem's angle and length. Measured vertically from the center of the handlebar clamp to an imaginary line that bisects the central meeting point of the extension and vertical portion of the stem. In the QBP catalog, a stem with a 90° angle will always have a rise of 0mm.
• Height (mm): The overall length of the vertical portion of the stem.