I have heard it said that when at lights its best to wait with your bike in gear ready to take off in case a car fails to stop behind you, at least until 1 or 2 cars have stopped behind you as a buffer. I have always felt safer holding onto the handle bars (as I would be in the situation above) however would give my brake light a flash or 2 then hold the font brake on until at least one car behind has complete stop. The reason given for the first suggestion (from different riding schools) has been so you are able to take off and reduce the impact with acceleration. The reason I think it is important to be holding on to the handle bars is so I go with the bike rather than have to get my gear rack surgically removed however I don't want to enter an intersection suddenly and just take off through it just after an accident. I am interested on other peoples opinions and experiences as I find this a less painful way of learning. :-P