Honda FourTrax Foreman TRX500FM1 2019 Owner's Manual page 181

Rear Brake Pedal Freeplay
RIGHT SIDE
(1) rear brake pedal
Inspection
Measure the distance the rear brake pedal (1) moves before the
brake starts to take hold. Freeplay, measurement at the tip of the
end of the pedal, should be:
9/16 – 13/16 in (15 – 20 mm)
If necessary, adjust to the specified range.
Brakes
(1)
9/16 – 13/16 in
(15 – 20 mm)
Servicing Your Honda 171