One theory with some positive research is that cramps may be caused by reduced sensory input to the golgi tendon organs and and increased stimulation to the slow twitch and cetain types of fast twitch fibers. Muscles that contract when in a shortened position are subject to increased cramping. Think calf muscle when swimming. Calf muscle is in a shortened position while still contracting.
Would it follow from this that a hamstring cramp on the bike may be caused by a seat that is too low?