Ah yes I would go with what Stewart suggests then the tangents will always be linear by default.
This always bites me in the butt and then I have to spend a bunch of time remembering how to fix it. It seems I use linear tangents much more then parabolic.
This is one of those things they changed from earlier versions of maya as I definately recall there being an ease in and ease out setting which I no longer see in maya 2013
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675