I'm shopping for a new chain, and I noticed some inconsistencies when discussing speeds. Specifically, speeds applied to the cassette refer to how many layer of gears it has (I presume). Speeds, when applied to bikes, refers to the total number of speeds it has with the cassette (or freewheel) multiplied by the chainring on the crankset.
Soooo... what do the speeds listed on a chain refer to (ignoring the compatibility issues -- those are very well documented)?
For example, if I have a cassette with 5 gears and a crankset with 2 gears, do I need a 10 speed chain or a 5 speed chain?