If you are sincerely worried about your biceps, a flat bar will do much more for you than an e-z curl bar. The e-z curl has it's place i guess. Some like to use it for skull-crushers, whatever. The point is, maximum contraction of your biceps comes from a totall supinated (turned out) grip. The e-z curl bar pronates your wrists. Here's an experiment..flex your right bicep. Now take your right hand and turn it inward so you can see the back of it. Did your bicep go slack? Now try the same thing (flex your bicep), but turn your right hand out. It should have a much harder contraction than when the hand was turned inward. The e-z curl causes your hands to be bent slightly inwards. It puts more focus on the brachialis muscle, decreasing the work your bicep has to do. IMO, it's worthless. Just try your curls with a straight bar next time and tell me how it goes. Make sure to let your arms extend fully in the downward position before starting the next rep. The olympic bar is often thicker than the e-z curl also, so you can work your grip simultaneously. Personally, I think isolating the biceps is a waste of time. I agree with the posts above though, they do get a lot of work from pulling exercises, especially reverse-grip pullups, rows, etc. Those exercises will give you some strength you can use.