Ok so i'm riding the bike yesterday, and i use the hand brake or the front brake what ever you want to call it. So as i'm about to come to a comeplete stop the bike starts vibrating. It seemed like It was comming from the front brakes like they are struggling to stop the bike. Any way so this came and went all day. When i use both brakes it's fine. My questions is what's going on do i need new brakes or just an adjustment?