From the Seafield Path go west along the top of Leith Links then {CYCLE PATH ENDS} follow Links Garden/Links Place to Queen Charlotte St. then
If dia_tyres_mm >= 28 then
turn right into Water St, right onto The Shore, straight across the junction then dismount, walk across the transporter bridge then select either the left or right pedestrian route to VC. (Quieter, but more dismounty)
Else
turn right down Constitution St, go straight across to the lumpier bit of Constitution St/Ocean Way then left at the roundabout to Ocean Drive. (Simpler, but involves Ocean Drive, though numpties are relatively rare.)
End If
It's quieter still to go down Salamander Place, Salamander Court, Elbe St, Cadiz St, Mitchell St to get to Constitution St (or Assembly St to get to the corner of Baltic St where there's no pedestrian crossing (though one was promised as part of the Leith Walk Improvement Plan)) but cobbles might not work with back issues.