Scary chain stretch

It's amazing just how worn a chain will still work fine with hub gears.
I recently changed the 16t sprocket on my folder for a 13t, and had to
take half a link out (and was surprised to find the chain had a half
link to take out (like this: http://www.63xc.com/toddp/halflink.gif)).
The 16t sprocket was itself a replacement a while back for the very
hooked one that was originally on it.
There was a sort of ticking noise with the new sprocket, so I got a new
chain as well, which I've just put on. It's very nearly half a link
shorter over the length of the chain (I've moved the axle forwards in
the horizontal dropouts rather than refit the worn half link - I think it
will be all right when I've tweaked the mudguard spacer a bit (it was
improvised as part of the change to 406 wheels).
(I've just seen http://www.wiggle.co.uk/Default.aspx?ProdID=5360021268
which is all half links - I'm sure it wasn't there when I was shopping.)

Alan Braggins wrote:
It's amazing just how worn a chain will still work fine with hub gears.

Your post got me to get out the tool and measure my 'bent chain.
I'm amazed that there's still no easily observeable change since 5000km
ago.