I ride in groups that can be 30+ cyclists at times and with that many cyclists someone is going to cramp. I can say for certainty that almost all of my cramps were primarily from fatigue and when one is suffering from a cramp stemming from fatigue, electrolytes and hydration will do little or nothing to help. From those in my group that cramp I often hear the same typical questions and answers.
"Are you drinking enough?"
"Yes"
"Are you taking electrolytes?"
"Yes"
"Are you eating enough"
"Yes"
When the person answers a confident yes to those questions then you have to trust that taking more electrolytes and more water may not be the solution. It is at that point one may want to break away from that old mindset and have a better understanding on the subject.
I am not eluding to a "one size fits all" kind of thought like the camp that only subscribes to "hydration and electrolytes" is the solution to all types of cramping.
In the case of myself and others in a very fast paced group ride one can find out that there are various levels of fitness and performance abilities. Some in our group are really strong cyclists and will absolutely tear the group apart with their pace on the front. Mile after mile the weaker of us in the group are riding above our fitness levels to the point where fatigue will play a potential major role in cramping, whether it be in the extreme heat or even in the cold of winter.
I still stick to the old school train of thought and use Endurolytes before the ride and mid ride. I use Hammer gels, Hammer Heed and Perpeptuem continually during the ride to replenish lost electrolytes and watch my time and miles on the cpu to feed and use these supplements during the ride at consistent intervals, but even with this I have still cramped and so do others in my group that try to hang mile after mile at a pace above our abilities. (that is not an endorsement for Hammer products. I just happen to get a huge discount on that brand)
Hydration, carbohydrate replacement, and electolyte replacement are a given and I notice that most of my group does as well. The only way to keep up in these fast paced groups and not bonk is to be constantly drinking and replacing lost nutrients.
So what is the point?
Not every cramp is caused by just electrolyte loss and dehyration. A number of people suffer from cramping based on sheer fatigue. What I have noticed now as I begin to be more disciplined with my training and stay within my prescribed training zones that fit my performance level using a power meter, I am not cramping. Here in the deep south I have been riding consistently in 100+ degree weather and I am still not cramping. So if you feel confident that you have properly hydrated and replaced nutrients you might want to reflect on the event and evaluate if you were fatigued before the event or going a bit above your fitness limts for too long of a period.
Another note is that I have come to training rides already fatigued from days of solo training and was pre-fatigued before the ride. I could sense in those first few miles that I either need to drop out of the fast paced pack or if I tried to keep up I was more than likely going to risk major cramping somewhere miles down the road.
Heat related cramps can again be prevented by lowering intensity levels. In this 100+ degree weather our group rides have shortened in distance and lowered in intensity for the safety of all riders.
Now that I understand what it is that causes my cramps I know to that I need to continue to improve my fitness level to hang with these fast group rides. As my fitness level rises cramping has becone less of an issue and again if the pace gets above my ability I can prevent cramping by tapering down the intensity level for the remaining miles as long as I taper before the first cramp is initiated.
References
Joe Friel
Ultra Fitness
Muscle Cramps | Sports Medicine Information
The Science of Sport: Muscle Cramps: Part III