Abstract: A support (10) for a backrest for a saddle-type seat (50) includes a pad mounting (11) secured to an in-use erect stem member (12) a part of which is, at a pivot location (18) remote from the pad mounting, pivotably secured to an indexing mount (19). The latter supports a cam (29) that is moveably engageable with the stem member (12), movement of the cam determining the part thereof that engages the stem member in order to cause the stem member (12) and the indexing mount to pivot one relative to the other in adjustment of their relative translational positions.