Honda BIG RED 2009 Owner's Manual page 139

Brakes
Check the pad for wear.
1. Remove the wheels (page 172).
2. Check the wear indicator groove in the pad.
If pad is worn to the bottom of the grooves, replace both pads as a set.
See your Honda dealer for this service.
FRONT
wear indicator groove
Always inspect both pads in both the right and left brake calipers.
130 Servicing Your Honda
REAR
wear indicator groove