My 1973 Raleigh RRA came with an Atom 6 spd. I remember being awed by the extra cog with the difference between it and the 5 spd Cyclo and my PX-10 being the high gear cog (13 vs. 14) not the low gear (21). In those days, I used the 21 for the hills!!
Malta (5" of new snow!!) NY