Pedal slip

[mahadevan.swamy]

I am having problems with my bike where when I gradually pedal to some distance, the pedal at some point slips for a moment causing my leg to fly off the pedal. In other words, when I keep pedaling and when I apply a downward force (on the right) to the pedal, it slips down so easily and then manages to catch on to regular pedaling. I don't know where the problem is and I am hoping someone in this forum can tell me that. Thanks