A few fragmented scenes - Our hero and his girlfiednd are on a bike ride when the bad guy & his friends chase them in a car. The girl gets away but the boy is beaten up (bad guys wear masks)
Later out Hero (a chemist nerd?) pours chemicals over bad guy's car and ruins paint job and tyres. Idiot bad guys put on masks again (this is in a school yard)
I thought I had this on a favorites list, but can't find it - any help would be appreciated.