mixing SRAM and shimano cogs........
when i was running 8-speed i was able to add a 13-tooth, 8-speed DA cog with built-on spacer between the 11 and 12 SRAM cogs and shifting was perfect.
i just tried the same thing with 9-speed using a new SRAM 9-speed cassette and a new 13-tooth shimano cog with built-on spacer.
bottom line is it does not work because the chain jumps like crazy on the 12 cog because of the profile of the teeth on the shimano 13 cog.
so i bought a shimano HG 50 cassette (11-32) and i hope i can drop the 32 and add the 13 between the 11 and 12 to give me the gears that i want on my 1 x 9.