indeed no lateral movement within the hub in use. To achieve this radically different mode of shifting gears, the hub featured a unique driver with a 4 spline keyed socket in the middle (similar to, though not interchangeable with, later 'No Intermediate Gear' AW drivers), into which sat a selector sleeve. The 4 cuttings on the selector sleeve (2 shallow and 2 deep, arranged alternately) enabled the selector sleeve to transmit drive from the driver to the backs of the two unique high gear pawls, with said pawls either allowed to engage the hub shell for direct drive (deep selector sleeve cutting) or tripped out such that drive is transmitted only to the gear ring (shallow selector sleeve cutting). Low gear then operates in the same way as on an AW hub, with the drive of the ring gear turning the planet cage (via the planet gears) – and hence the shell – at a reduced speed. The S2 hub features three low gear pawls mounted in its shortened planet cage, necessitating a low gear freewheel track with twelve stops instead of the 10 which would be found on a contemporary AW, this means that an S2 freewheeling in low gear will tick more frequently and more loudly than an AW in low gear at the same speed in a wheel of the same size. Because of this difference in the left (low gear) freewheel, and the short planet cage, the S2 has a gear ring pressed into the shell near the middle, with the mechanism occupying little more than half of the shell volume and the rest being left empty. For this reason, the S2 has a unique shell and its internals cannot be installed in the shell of another model. The S2 is an unusual hub, with only 12,500 produced, and they are rarely available for sale. The hub was discontinued in 1972 and should not be confused with the S2, S2C and S2K hubs currently manufactured in Taiwan by Sun Race Sturmey-Archer. Hybrid gear options Sturmey-Archer hubs are seen by many as an alternative to Derailleur gears, however on many models of Sturmey-Archer hub, the two can be combined to offer a setup with many of the benefits of both systems - offering more, closer spaced, gears while continuing to offer a very wide overall range. The majority of Sturmey-Archer gear hubs can be converted to hybrid