Joined: Aug 2008
Posts: 13,140
Likes: 2,162
From: Ann Arbor, MI
Bikes: 15 Kinesis Racelight 4S, 76 Motebecane Gran Jubilée, 17 Dedacciai Gladiatore2, 12 Breezer Venturi, 09 Dahon Mariner, 12 Mercier Nano, 95 DeKerf Team SL, 19 Tern Rally, 21 Breezer Doppler Cafe+, 19 T-Lab X3, 91 Serotta CII, 23 3T Strada
I agree with Carbonboy, and think there are two sources of cramps: muscle fatigue and dehydration.
Preventing dehydration with an electrolyte drink like Endurolyte is key for intense workouts and when you're really sweating. Caloso is right that magnesium is a key component of any electrolyte supplement, but also salt, to help retain some fluid in cells before sweating it back out. I've been very happy with Cytomax's 'pre/during' drink mix, which I get at Performance Bike.
Just as important probably, is training appropriately. You need to condition muscles for max output, and if you train a bit above your regular use level, you should avoid cramping (provided you're also hydrated).
Taking Tums to alleviate cramps in process is a new, and interesting, tip, so thanks, CFB!