Originally Posted by
taras0000
Typically, any lockring will do, but it depends on which hub you have, not which cog you have, as it is the hub that accepts the lockring, not the cog. Most hubs use the ISO standard, but there are some out there that use separate standards.
33.5 mm × 24 TPI Campagnolo, Gipiemme, Phil Wood, Miche
1.29" × 24 TPI Shimano, Suntour, Formula, Dimension, Suzue, Surly, Zipp, Corima - This is the ISO standard.
33.0 mm × 1 Mavic
There is one are two cases where the lockring/cog combo matters. One and that is when you use a 12 tooth cog. They come with their own special lockrings that have a smaller outer diameter, so that the chain doesn't ride on the lockring instead of the cog. I have only ever seen this combination use the ISO standard.
The other case is when you use the 33.5 mm X 24 TPI Miche hub and a 13 tooth cog, The Miche lockring is just enough bigger to cause the chain to ride up on the ring and periodically drop into the spanner slots, making setting chain tension a Sisyphan trial. I haven't tried the 33.5 x 24 TPI hubs of the other makers, so no advice there.
I do not know where to buy 12 tooth 33.5 X 24 TPI lockrings. A good machine shop can re-thread an ISO lockring to the bigger 33.5 x 24. TiCycles has done it twice for me and the re-threaded rings work beautifully, but they cut the threads on a lathe and not with a die. Between that and the very hard metal of the 12 tooth lockrings I have found, the machining was not cheap.
I learned all this dialing in my road fix gear to ride in the mountains. I use a small 1/8" chainring in front and all the 1/8" cogs I've ever heard of. (So far, 24 to 12.) The bike has done the week of Cycle Oregon 5 times (and never seen a freewheel).
Ben