Haven't improved my mileage as much as I had hoped.   Planning on the 40 mile route myself.    
 
Was up to 35mile ride before a vacation interupted the routine for three weeks.   Would have just gone for resuming my regular 35mile route,  but Hot Rocks intersects my normal route in enough places to be annoying.
 
Told them last year they need to stay off my streets.    (Actually made a charitable donation and bought a t-shirt by registering as I was riding past the registration area toward the end of my ride having started my normal ride unaware of the organized event to start later.)
 
If you see a 11-12mph trike with a big USA flag and small blue route flag on it... it was me.  Try not to stir up to much dust as you blow by.