Maybe you saw my post on the Nishiki Ariel that I'm restoring. Well, I need a chain. I feel dumb asking this - but what do I buy? I've done some looking, and most of the chains I see are specified as 9-speed or 8-speed chains. I'm assuming this refers to the number of cogs in the rear. My Ariel has 7 cogs. Will one of these other chains work? Do they have different gauges now depending on the number of cogs? What do I buy? It seems like BITD there were just 2 gauges; wide ones for BMX and thin ones for multi-speed bikes.

the 9 spd chain has narrower links, they don't work on the really old style chainrings. I would pop off the back wheel and bring it into the bike shop and make sure the new chain 'seats' really well on the cogs.

I suspected that might be the case. Thanks for the advice on taking the wheel to the store - however I was hoping to save a few bucks and buy the chain online. Maybe this will be one of those cases when I can't be chronically cheap.

An eight speed chain should be fine. The nine speed will definitely be too narrow.

Any scram 8 speed chain will work down to 6 speeds and are easily available from 10 - 20 bucks. Remember that you usually want to replace the cog set at the same time.