Re: [CR] Definition of a sprocket.

> The 'sprocket' is the projection or tooth on the wheel. > A 'cog' is a wheel with a series of projections, or > sprockets.

I must admit that every dictionary I've consulted has it the other way around, as does the "Complete Guide To The Chain": http://chain-guide.com/basics/1-3-sprockets.html

I also submit the entries in the Glossary compiled by the late Sheldon Brown. I didn't agree with him on everything, but he was truly punctilious about the use of language: http://www.sheldonbrown.com/gloss_sp-ss.html#sprocket http://www.sheldonbrown.com/gloss_cn-z.html#cog

BTW (not that they necessarily have the last word on English usage) but currently Shimano seems to be using the term "sprocket" to refer to those toothed disks: http://bike.shimano.com/media/techdocs/content/cycle/SI/Dura-Ace/SI_1Z80B_001/SI_1Z80B_001x13_v1_m56577569830648477.pdf

BTW the first time I heard the term "cog" it was in reference to mountain railways, rather than bicycles.
      Best regards,
      Fred Rednor - Arlington, Virginia (USA)