Thomas54

I just started riding again with the local club. The 30 mile distance was not a problem; my typical weekend ride alone is in the 40-50 mile range. As expected the pace was higher and my heart rate climbed. But at about the 10-12 mile point some of the top-guns started to slow a bit so my heart dropped into a comfortable range. But at mile 15 both of my calves started to cramp and soon after started to lock up my whole leg. I had to drop off the pace line. Once my pace was reduced the cramping went away.

Ok is this most likely:
Fitness, I am just not used to riding that fast?
Muscle development, need to hit the gym?
Seat position, I think my seat may be a tad bit too high?
Nutrition, not enough of the right fluids?

Thoughts

sprince

Not enough fluids and electrolytes and/or poor lower leg circulation. If you are already doing 40-50 mile weekend rides for a number of weeks, your calf muscles would have long since adapted.

DBA

intensity plays a factor as well. The load/adaptation for LSD is certainly different than that of sprints/intervals.
That said, there's really not enough info to know why you cramped, OP. Best guess would be fluids/electrolytes, but no way to say for certain as I don't know your fluid intake, your diet, your training regimen, your sleep habits, etc.

berner

There does not seem to be a single cause for cramps that applies to everyone. Those causes, singly or in combination are, fitness, insufficient fluids, and loss of electrolytes. Since the pace of the club ride was faster than your typical ride, that was a contributor but as your fitness improves, that cause will subside. The ride was not long enough for insufficient fluids to have contributed to cramping. If your electrolytes were already somewhat low, that may have caused cramping. You can purchase electrolyte tablets which would be worth a trial at little cost.

I'm prone to cramps also when doing a longer ride than usual. I've found Sport Legs tablets to be a big help in warding off cramps.

ColnagoC40

Nutrition, as already mentioned above. It could be something missing in your diet in addition to electrolytes before the ride.

OldTryGuy

Could have the intensity for the 12 miles not allow for an proper warm up? Hammering too soon can cause issues.

Machka 

All of the above ... but especially not enough water and electrolytes.

What did you have to drink during the day before the ride?

krobinson103

Gatoraid or something similar. I can't ride over 60 miles without a bottle with me. I drink a little bit every hour or so and any cramps just vanish.

Thomas54

(OP)

I usually ride with one bottle of Gatorade and one bottle of water. I typically drink the Gatorade first and then switch to the water. That evening I had just two water bottles.

krobinson103

That was your problem then. Not enough electrolytes. Everytime I run out of gatoraid I know I will cramp up. I'd imagine any kind of sports drink or mineral tablet would do the trick.