Originally Posted by Chris_W

Chainrings are not really speed specific, only the spacing between them needs to be appropriate for the chain width. The spacing between the middle and big rings is a bit difficult to adjust, but the spacing for the inner ring is really easy to modify with spacers, plus most inner rings are simply flush with the mounting posts, and so all end up being in the same plane. Having said that, Shimano's inner rings are spaced a bit further away, so if you are switching a Shimano chainring on a Shimano crankset to some other brand of ring, then you do normally need to add narrow spacers between the new ring and the mounting posts. If it is not a Shimano crankset then you should have even less to worry about.

Anyway, my point is that most chainrings should work, don't worry about the official speed designation, the teeth on them are all pretty much the same width. It is the spacing between the rings that you have to worry more about. I believe there is something about this on Sheldon Brown's site somewhere.

I use TA Specialites rings when possible and Sugino otherwise (because they are cheaper and are available from a more local source), and have been happy with both. The TA definitely seem to have a better finish and look like they'll wear less quickly, I haven't worn out either type yet, but the longest-serving one only has about two years use on it.