Hi, I have 2009 Specialized Rockhopper basic model that I bought new few months ago and maybe put a little more than 300 miles on it so far. Here is the story - I installed clipless pedals last week and as I never before rode clipless I fell with the bike a few times when stopping because I couldn't get my feet unclipped in time - I guess it's a rite of passage. So anyway, after the last fall my rear deraileur started acting up. Every few minutes or so my gear would jump to a higher one and then jump back. I can't figure out exactly when it happens or what makes it happen - it happens intermittently every few, sometimes up to 5 minutes, sometimes when I push hard, sometimes when I barely push on pedals.
Any ideas what might the problem be and how to fix it?