Originally Posted by
HillRider
All makers have their cogs "keyed" so they can only go on the freehub body one way (well, they can go on flipped over but that's easy to avoid). That way the shifting ramps and shaped teeth automatically line up properly. If you use the same maker's cogs throughout, you can mix and match at will.
Shimano/SRAM cassette cogs CAN'T be flipped over. The wide spline is offset so that you can't.
Shift ramps ARE designed to be used with specific adjacent cogs.
A 14T cog used in a 12-14-16 combination IS different then a cog used in a 13-14-15 combination.
That said, sometimes it doesn't really matter.
I made up a custom cog with 12-17 spaced at 1T increments. Each adjacent cog is a mismatch, but since they are only 1T apart, they shift far better then the "matched" cogs did with their 2-4T differences.
I think at least "some" Free Wheel cogs could be "flipped".
Sheldon's site appears to be down the last couple days. Sure hope it's not permanent!
