I used to use "Passing on your left", and now sometimes still do, but I have a bell now and tend to use that more (occasionally saying something too). If they actually move over, I add "Thank you" as I pass.
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Bikes: 1996 Eddy Merckx Titanium EX, 1989/90 Colnago Super(issimo?) Piu(?), 1990 Concorde Aquila(hit by car while riding), others in build queue "when I get the time"