Just commented on this elsewhere...

Used to rock 76-as much as 81 gear inches and spun that like a gerbil on crack... I was training to enter master's level racing and knocking down 10,000 miles a year.

Fragged my back and did permanent nerve damage which affects my left leg and keeps me from doing any high load mashing so I geared it way back to where I could keep a high cadence with 1.5 legs and can still keep a pretty good pace and on good days can still show the kids a few things.

Spinning faster is more efficient at any speed so no matter what I am riding or the gear... I maintain a higher cadence.