My neighbor has a Camping World 'Adventurer' folding trike (not allowed to post a link but it's on the Camping World website) with a 3 speed 'Sturmey Archer' branded gear-set and coaster hub brake. It's a nice unit!

Its longer chain runs over a simple tensioner that has no adjustment left - the chain desperately needs replacing although the chainwheel and back sprocket don't look badly worn. I maintain her trike when I'm in the US but right now I'm not so she's had to take her trike to the local bike shop for puncture repairs and servicing. The local bike dealer didn't replace the chain and appears unwilling to tackle what I see as a simple job. When I get back I want to source a replacement chain because the nearest boxed one in the shop is one link shorter than needed - I counted the links on old one to check.

I'm 71 and learned my bike stuff quite some years ago but can't figure why bulk, loose chain can't be 'cut' (split) to yield the correct number of links. But the bike dealer seemed unprepared to do that and I'm left wondering if there's something I don't know.

Are chain link dimensions 'universal'? ie Is the link size of the Chinese original the same as replacement chains for sale in the USA? Will a new 73 link chain be the same length as the original 73 link one used to be when new? Can she order one that's the correct length or will she have to order a longer one for me to split?

Sorry if that's a really basic question but I don't want to waste someone else's money.