text: According to the conservation of energy, your answer is negative. The effort that biker put in each case is consumed to resist both the friction and the work needed against gravity. On flat path, no vertical work is made so his energy (name it E) is totally consumed for resisting friction (f) against movement of him (M) and his bike (m) along the path (L):\nE=(M+m)*g*f*L\nNow suppose a terrain path (LL) which is surely longer than the straight one (L) which have a max vertical difference of H. The work he must do to move to the top is (M+m)*g*H plus the work needed against alongside friction. The energy will change back to kinetic form during descend session, and therefore cancels the initial effort put. The only work that is to be done is resisting against friction over the longer path, which is certainly more than the straight (shortest) path.