Presuming that I concede I cannot tell by eye, how do I figure if a chain is 1/8" or 3/32"? I'm thinking that as I have a micrometer, I try to measure the thickness of the rollers. Eh?

Pretty sure my 1993 Stanley needs a new chain, don't want to remove the old one until I am back form the LBS with a new one.

True confession: the 1993 Stanley is not a bike, but my garage door opener. Likeliest size to me is 1/8".

If you have 1/8" and 3/32" drill bits available, could you just see which fit?

Get a SRAM PC-1. Their outside width is narrow enough for most 3/32" applications, while the inside is wide enough for the thicker 1/8" cogs.

Thanks, that might be easier than using a micrometer while on a stepladder.

Thanks, bookmarked.