landsurfer wrote: ... Any mechanic, fitter, technician or engineer will tell you that bolts, washers and locknuts are never re-used .... doh !
In which case they would usually be wrong. D'oh!
Some bolts are 'one time only' use, but most are not, since their correct use involves only elastic loading.
If in doubt refer to the manufacturers. But imagine if it were true; you'd have to bin your stem bolts every time you moved your handlebars, and throw away your QR skewer after each use, etc etc....
Not that I fancy it in every case, but Philidas claim that several of their locking nut designs are (in contrast to many other varieties) re-useable.