Originally Posted by SweetLou

That's the stated capacity, but you can get more out of it. The capacity is listed for cyclists that might use the small/small combination. The chain will rub front derailer in this situation, but if you only use the bigger cogs in the rear with the smaller chainring, you can push the limit a bit farther. Also, by using a shorter chain and not using the big/big you can push the rear derailer capacity.

But you risk the chance of using the wrong combination and bad things can happen.