Im 5'9 and ride a med. Specialzied enduro. I was riding with a 50mm sunline stem its great for everything but xc it is just to short for riding cross country. For me to like cross country I have to be able to have fun coming down the hills. Keeping in mind I really want it to feel as much like a mini DH as possible while still being able to climb up some hills with out killing my lower back.Think a 65mm would help much or would I have to go to the 80mm to really make any difference? thanks for any advice