Keep dry items separate
Use a dry bag for spare socks, a small towel, or any layer that should stay clean.
Pack one small towel
A microfiber towel is useful for hands, seats, gear, and quick cleanup after a wet trail.
Use light weather shells
A poncho or light rain layer should be reachable without unpacking every other item.
Protect small electronics
Put cords and small devices in a cable roll or pouch before the rain starts.