ISO 9129:2008 specifies a measuring method for determining the moments of inertia of the motorcycle and of the motorcycle/rider combination. It applies to two-wheeled motorcycles.

Other measuring methods can be used if it is demonstrated that the results are equivalent.

Measurement results obtained exclusively by the method described in ISO 9129:2008 cannot be used for an evaluation of vehicle stability because they deal with only one aspect of this very complex phenomenon.