I'm still waffling between a 54cm or 56cm Specialized Roubaix or Roubaix Sport, both of which have the 1.5 future shock system. Various people have told me you can change the fit of a bike by adjusting stem height or changing out stem for longer or shorter versions. I know the Roubaix future shock is not actually part of the stem but is the stem of the Roubaix height adjustable and can the stem itself be changed out for a different model or is it a Roubaix proprietary stem? Thanks.