Bending and Twisting Properties
Appendix II, 2b requires that:
| At any point along its length, the shaft must:
(i) bend in such a way that the deflection is the same regardless of how the shaft is rotated about its longitudinal axis; and
(ii) twist the same amount in both directions.
This Rule effectively restricts shafts from being designed to have asymmetric properties, so that irrespective of how the club is assembled, or whichever way the shaft is orientated, it will make no difference to the performance of the club.
There is no easy method of measuring a shaft against this requirement in the field. However, a standard shaft with a circular cross-section would almost certainly conform unless there is specific evidence to the contrary (e.g. advertising claims). A shaft which is not symmetrical in all axes (e.g. a shaft with an oval or rectangular cross-section) could also conform, but due to the unusual nature of such a shaft, it is more likely that it does not. Manufacturers of shafts with unusual cross-sections or other unique features would normally have submitted a sample to The R&A for a ruling prior to marketing and/or manufacturing. Whether such a ruling exists can be confirmed by contacting The R&A.
Many graphite shafts have a small “spine” or “spines” running along the length of the shaft which may make them bend a little differently depending on how it is fitted to the head. The existence of a small spine is generally regarded as being the result of normal manufacturing processes and therefore not a breach of Appendix II, 2b. As previously noted, The R&A recognises that it is difficult to produce a perfectly symmetrical shaft. Therefore, provided that the shaft is manufactured with the intention of meeting the above requirement, The R&A will apply a reasonable tolerance when evaluating shafts for conformance.
Manufacturers of clubs may orientate or align shafts which have spines for uniformity in assembling sets or in an effort to make the shafts perform as if they were perfectly symmetrical. However, a shaft which has been orientated for the purpose of influencing the performance of a club, e.g. to correct wayward shots, would be contrary to the intent of this Rule.