Yes, SCRAMBLERS is a Scrabble word!

Letter values in Scrabble US: S 1, C 3, R 1, A 1, M 3, B 3, L 1, E 1, R 1, S 1.

Is it a valid word?

SCRAMBLERS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a rapid mover; someone who scrambles
a lightweight motorcycle equipped with rugged tires and suspension; an off-road motorcycle designed for riding cross country or over unpaved ground
electronic equipment that makes speech unintelligible during transmission and restores it at reception

Also: trail bike, dirt bike.