I just got finished adjusting and lubing my chain when I went on vacation. When I came back, I hopped on the bike for a nice ride. For some reason, when the bike is stopped in first and the clutch disengaged, it tries to pull forward and will not allow me to roll back. Also, if I have it in gear with the clutch disengaged and am running under 10 MPH, the chain starts jumping up and down. Did I over tighten the chain or ??? Any help is appreciated.