"After Gear Fourth ends, Haki is exhausted. Luffy shrinks into a tiny, weak, comatose old man for 10 minutes. He's completely defenseless—a massive risk that fits his 'all-or-nothing' style."
Gear Fourth operates on a principle distinct from previous gears. While Gear Third inflates the body like a balloon, Gear Fourth inflates the rather than the skeletal frame or general mass. one piece 4th gear