Long Distance Competition/Ultracycling, Randonneuring and Endurance Cycling - Help me figure out what went wrong, and how to get better

Went on my first group ride the other day. Hilly country.

I've ridden as far as 50 - 60 miles in a day, but at a medium pace.

We did a 30 mile group ride - and it was pedal to the medal. We averaged about 19 mph if that tells you.

About 27 miles in, I started to 'bonk' - I've felt that before.

But about 1 mile from our end, my legs physically started seizing on my front quads.

I had the worst 'double charlie horse' ever and had to stop and wave everyone on. About 10 minutes later it subsided so that I could barely pedal in granny gear and limp in.

That night, I took a hot bath and my leg seized on and off for the next few hours.

I figured you guys would be the most experienced with stuff like this.

I've been riding 300-400 miles a month since last August, and I bike commute - even in the rain - so I've been biking through the winter - all of it.

Google causes of cramps. Be ready to read for hours and hours. There is no single definitive answer. Actually, you will find many people with single definitive answers. There was a guy with a theory about the muscle being confused... thinks it's stretching too far and is contracting to protect itself. I don't find it now, but it was the most plausible explanation I've ever read.

IMO, speaking technically ;), you rode beyond your ability, your muscles' chemical/electrical/mechanical systems got screwed up, and they went bezerk. You need to either not ride in hills with guys faster than you, or do it more often.

No need to google. You rode a lot harder than you are used to. Solution: ride a lot harder once a week. A lot harder. Your metric should be: if you can still walk when you get back from that ride, you could have gone harder. Even simpler solution: ride with that same group every week. After about 4 of those you'll stop cramping, and not only that, after a couple more months, you'll take a couple hours off your 200k time.

It has little or nothing to do with hydration, electrolytes, or stretching. I have noticed that if I start to cramp and go off the back, it maybe helps make the cramps go away if I up my hydration and electrolytes, or maybe it's just the easing off that helps. Hard to know for sure, but it doesn't hurt to work on those things, unless you get to drinking so much you have to stop to pee and lose the group. That's no good, either. One of the fastest guys I ride with will drink maybe 1/2 bottle on a 60 mile hard ride, while I'll finish two bottles.

In any case, that cramping thing will only happen when you first ramp up your speed in the spring, then it will go away. Definitely don't be afraid of this happening again. Go for it. Try to make it happen. That's how one gets fast.

Bottom line: you didn't do anything wrong. On the contrary, you did something right. I've rolled in more ditches than I can count, watching the little animals run up and down my legs under the skin. Usually the final 20% grade is what gets me. I was never a great climber. But like I say, after a few of those, you're pretty much good to go. OTOH, even when I've been in shape, a long, hard, successful attack on a major pass might find me unable to dismount the bike at the summit.

Definitely don't be afraid of this happening again. Go for it. Try to make it happen. That's how one gets fast.
+1 to that and most everything else he said. It's a typical reaction to pushing yourself beyond your limits, which is exactly what you have to do to get faster.

Riding with a fast group is very demanding, but gets easier. A group maintains a pace, but your role in the group determines your effort. The hard way to ride in a group includes dropping off the pack and catching up or spending too much time leading. The easy way to ride in a group is to stay right behind a larger cyclist. (Unfortunately for me, I'm often the largest guy and I end up doing much of the pulling)

Most riders, new to group cycling, spend a lot of energy doing it the hard way. It’s a part of the learning curve.

Like the others have said, It’s a great way to build fitness and speed.