Yeah, I think I'm just over-thinking it because I've never done it before and I plan to stick with the same chainring but lose teeth on the sprocket. Which, given that I can't really pull the axle any further back than I currently have it, means I'll need a shorter chain. Which is fine, but I just don't want to over-shorten it and then have to put links back in, if I can avoid it. My current chain seems to have a quick link actually, though it seems to be different from the ones I'm used to using with my 10 speed chains, so I need to fathom how that works and if I can fit one to the new chain once I've bought and shortened it. Cheers.