He started to play the drums in elementary school (3rd or 4th grade) after seeing an Aerosmith concert. His mother knows Joey Kramer, Aerosmith's drummer, so he got to go backstage and see the entire production. Rob also plays the piano in his spare time. Linkin Park is not his first band. When he was around thirteen, he played in bands with his friends and they covered songs that were popular at the time, including Nirvana's Smells Like Teen Spirit. It was around that time he met Brad, and they played together for about a year in a band they called Relative Degree. They practiced a great deal, but after their first and only show, it fell apart.
According to Brad Delson, the guitarist for Linkin Park, Rob is a perfectionist. When they rehearse or record, he is known to never play a part wrong, and will always point out things that are not up to par from the other band members.