ABS is on both wheels. in some cases, depending on the bike, there is a linked system that applies pressure to both front and rear brakes no matter which lever you apply. On the Roadster, they are independent. Smash on the rear pedal and you will get a brief chirp and then the bike will slow quickly. Same with the front. but unless you are riding on a dirt road, you should always apply both brakes. Its a great habit to get into and will save yer bacon at some point.