Pace

Av. Spd (mph)

A-

—

A

—

B-

—

B

—

C-

—

C

—

D-

—

D

—

E-

—

E

—

A+ = B- B+ = C- C+ = D- D+ = E-
hilliness = (feet_of_climb / miles_of_ride) / 25
average speed = zero_hilliness_speed − hillness †
† formula obviously breaks down at large hilliness values, but is easy to grasp & calculate manually