But that extra 9mph from 70 to 79 will take 30rpm totalling 230rpm.
Analytical cycling calculation
http://www.analyticcycling.com/GearCadenceSpeed_Page.html
Speed 79.0 mph
Chainring Teeth 53. teeth
Cog Teeth 12. teeth
Wheel Diameter 0.663 m
Cadence 230. rev/min
World class elite track riders achieve high rpm's for brief periods (to train CNS) with little resistance on an ergometer in laboratory like conditions without concerns of traffic, winds, balance, draft, dynamics, rolling resistance, etc.
On the competition track they would be geared to max out at 160rpm's tops.