Question...

I've been running into issues after hitting the 50-mile mark of my longer weekend rides. Usually these rides are 65-70 miles in length but my body shuts down at about 50 miles. I feel great through out the ride ...I can keep up and feel fairly good on the hills...it's when I hit a certain time frame I have nothing left!

Is this an endurance thing? I feel like I'm in fairly good shape.. I ride 3-4 times a week, twice during the week in our local training rides. Which are 33-38 miles at 19.5/20 mph average.

Or is it my nutrition? Yesterday, I drank two bottles of water and a bottle of gatorade in four hours, ate a Snickers bar at the rest stop and ate two Clif blocks every hour. But, still limped home by myself for the last 7 miles. Interestingly, I was starved when I got home...could it be I didn't have enough calories the days before the ride?

If anyone has had this problem or any advice..I would love to hear about it?