My mountain bike ( cannondale jekyll) has a rear shock adjustment that changes the BB height 1+ inches .. and also changes the head tube angle.... so it is hard to tell which has the greater impact.

in the cross country mode.. the BB is at it's highest point and the head tube angle is 70 degrees.. good for navigating switchbacks, etc.

in the freeride mode the BB is at it's lowest and the head tube angle is about 68 degrees... greater stability on rocky downhills.

I set mine "in the middle".. because in the freeride mode, I hit the pedals on rocks, etc and in the cross country mode... I endo when going off steep drops,e tc.