Another of those things that should be obvious and all the maintenance guides assume you already know, but that would be embarrassing and expensive to get wrong. Chains: the maintenance guide I've been reading keeps referring to "7-speed chains" "9-speed chains", etc. In the store, the boxes for chains are labeled the same way. This refers to the number of gears on the rear cassette, and not the total number of speeds, right? In other words, I have double crankset in front, and a 7-gear cassette in back, so I'd need a 7-speed chain, right? I think what confused me is that I see 10-speed chains, but I don't recall ever seeing 10-gear cassettes. Thanks.