since im upgrading to a track chain (1/8), it takes a wider track cog and chain ring, to minimize left to right movement (think small tooth in a big whole = baggy). normal chains are thinner and less rigid, allowing left to right movement to handle the angles incurred while shifting. apparently, track chains use a "full bushing" design, while normal 3/36 chians are "bushing-less."

since my options where miche and shimano, and im not at all happy with my rusted-to-my-frame shimano bottom bracket, i went with the miche option, one tooth shy of my current track ring (17), for a slightly taller gear ratio, aka slower on the start, and faster at the peak.

the cool thing about this track ring, though, is that its two piece; instead of a threaded cog (like normal), its got a threaded seat that then accepts the miche cog. the upside is that, when this one wears out, or i feel like changing the tooth count, i can simply unscrew the lock ring, and pop it right off.