I count around 8 mines (probably 10 - 12 engine houses) on Bob A's 1996 GFL map. But as Spitfire says many are not on the GFL and some of those that are, are not on the trial.
It is really a cycle trail rather than a carefully planned route for those interested in all the major mines in the area.
For example there is no Dolcoath (1/2 mile diversion) nor Robinson's shaft or East Pool ( 1 mile diversion), West Basset Stamps(1/2 mile?) , Doesn't go through Wheal Buller workings only on edge of it (Cross the road, take path to Lanner to see more),to name but a few...
King Edward mine museum is on the route, but only normally open on Sunday mornings in the winter, good place for advice, books etc.
Is it safe to come out of the bunker yet?