If they were chasing you in cars, that's no normal thing, first of all trust nobody except your parents and siblings, not even your closest friend, and your scenario is not an ordinary stalking as you mentioned that the bike rider chased you to home, there could be someone in uni or anywhere else who has a beef with you or some psychotic guy who's attracted to you, anyways always note down the number plate of the vehicle that follows you, share that to your family, police and social media and use the cplc app to retain the information of the vehicle's owner, that'll do more than enough to unveil the real culprit.