Originally Posted by
repechage
Regina for a long time was the standard with all cogs threading on and it was a bit diabolical, at one time i could cite what position could go where and what body type, (standard or close ratio body) was needed, but as the cogs are a challenge to locate that information only interesting. Atom cogs were interchangeable even, I suspect there was a license agreement.
Then came the Japanese, with freewheels that allowed a number of cogs to slide on, Maillard also had this concept but much less acceptance. Fine for five cogs, it took follow on efforts by Suntour and Shimano to end the reign along with Regina's reduction of tolerances. Some of the Cx and BX and America free wheels work well, I have a few but the party was over for them by the 80's and soon freehubs would kill off Regina's freewheel business. They still make chains but mostly for motorcycles and industrial applications.
And somehow Zeus got lost in the shuffle (well, except for the splined remover interface it shared with Atom and later model Regina). Zeus actually tried to cover all the bases, as it could be removed with either the superior splined remover or the traditional, or inferior two-prong remover. All the cogs except the final cog shared the same spline pattern, much like a modern freehub, with the final cog threaded in place to hold things together. And no spacers were needed as the cogs were machined to provide the necessary clearance.