How would a bear get a crocodile on its back, though? Certainly impossible if the bear's standing on its hind legs and the croc goes for the legs and breaks them, which is probably what would happen. If the bear were on all fours it may have a chance, but then again that's exposing the head and torso to those insane jaws.
For the record, I'm not talking about the average zoo type crocodiles here, I mean the insane 15 foot long behemoths that weigh as much as a car or two. Grizzlies are obviously huge too, but they seem to be a little clumsy when dealing with something that low to the ground and streamlined. They usually go after mammals, not low-slung reptilian rockets with hydraulic heavy machinery for a mouth.