more likely root cause is further away than where the pain presents: the high hamstring tear is near insertion at pelvis?
so with plantar tightness, calf tightness, ham tight - everything is under tension. as you bend over, the whole dorsal line system tension is increased, especially noticable at the insertion at the ischial insertion. butt hurts.
so more upright, ie, mtb, less tension on the dorsal plane.
release/improve belly of hamstring muscle tension. release calf muscle tension. improve anterior pelvic strength (lower abs core etc)