Canon has Tim Drake the third Robin figuring out who Batman is from spotting that Robin used the same aerial maneuvers he had seen Dick Greyson using when he went to the circus as a child. Dick had been the youngest person the do a quadruple somersault and Robin was shown in news footage doing one. So if Dick had been Robin then Bruce Wayne must be Batman. So he walked next door and said he was going to be the new Robin after Dick refused to go back to the role.
