Originally Posted by
gregf83
I don't know about the headache but you're supposed to be sleepy after a hard 3 hr ride particularly when you don't do them very often. A short nap should help as would more riding and increased fitness.
Weighing yourself before and after the ride is good advice to determine if you're dehydrated.
Yeah, I don't think being tired after a hard 3hr ride is weird, either. The headache sounds like a classic heat exhaustion symption; are these hot weather rides?
Try drinking more, and see if that helps.