If the socket's wall is thin enough, I've always been able to get a 5/8" (0.625") socket to work where a 16mm (0.630") is specified. I know that 16 mm sockets exist, but my sets don't have one. I don't think I've ever owned a 16 mm. socket (or other wrench), nor needed one, as long as I had 5/8" stuff.
harvey sachs mcLean va USA (where we are imperfectly schooled in Metric yet)
John Thompson wrote: "...many people replaced the 16mm bolts with standard 15mm bolts. The threading on the bolts was identical to that Campy, TA, etc. used, it's just that Stronglight (and Zeus) used a 16mm head where everybody else used 15mm. Park and VAR both offered 16mm "peanut butter" wrenches for Stronglight and Zeus bolts for the purists who kept the original equipment.
But the extractor threads couldn't be worked around as easily.
-- John Thompson (john@os2.dhs.org) Appleton WI USA