The biting power of a dog depends on what weight he went into, how he was conditioned during the keep, how well the keep was, and the size of his opponent. They both could come in at the same weight but if the other dog was a bigger dog overall, your dogs mouth won't be as affective. Bringing in a dog at it's best weight will have him bite hard for the whole deal. Under weight, and he'll bite hard for a short period of time then tire out. Over weight, he'll bite the hardest but he will also run hot sooner.
During his keep, if he is over worked then hell lose his mouth. And if his mouth doesn't get enough rest before the deal, then he wont have much mouth.
I wouldn't use the spring pole in his keep at all just to be on the safe side.
There's 3 things I don't do in a keep: No jumping, no spring pole, and no pulling on walks. He will most likely get hurt in those exercises than doing anything else.