The 2mm Scale Association standard defines the track and wheel geometry for 2mm scale modelling, set down by the Groves in the 1960’s. Its normal form is for 9.42mm gauge (standard gauge track at 1:152 scale). Having a clear set of wheel and track dimensions means that models built to the 2FS standard work reliably; one cannot alter a wheel flange or tread dimension without also considering the impact on crossing noses and check rails.
At 1:160 scale, the FiNe standard removes 0.45mm from the track and back-to-back distances, but keeps other aspects of the geometry unchanged.
Many 1:148 modellers (British N scale) use at 9.42mm gauge, with track and wheels to the 2FS standard. In this case the track is slightly under scale gauge. But, with the overscale components in coupling rod, cylinder and bogies clearances, this anomoly can work in the modeller’s favour, much like EM is used in 4mm scale as the pragmatic finescale solution. The net result is much improved appearance compared to commercial N track, particularly through turnouts. With the recent introduction of flexible plastic sleepered track, the sometimes tedious process of building yards of plain line has been eliminated.