Measure crank width correctly
How do I measure the width of my MTB cranks correctly? We often hear this question from our readers. Here is the answer from our experts.
The Q-factor describes the width of a crank and should be as small as possible for biomechanical reasons. A Q-factor that is too large can even cause knee pain. The easiest way to measure the Q-factor is with a folding rule: To do this, bring the crank into a horizontal position and place the folding rule on one side at the height of the pedal from above. To do this, insert the folding rule through the spokes of the rear wheel. Now turn the other crank arm backwards until the arm rests on the folding rule. The value can now be read off exactly.
The value is usually between 156 and 173 millimetres.
Double cranks are generally narrower than triple variants. Some examples of the Q-factor of MTB cranks:
- SRAM XX = 156/166 mm
- Shimano XTR = 163/168 mm
- Shimano XT = 174 mm
