I can relate! Here's what I did: Heed by Hammer Nutrition mixed with a little Perpetum, sorta 50/50. Straight water as well, but in this heat 100-105, straight water "ain't gonna do it for long"...then Hammer gels, I sound like a commercial for them, but they work! Developed by scientisits that do the events and couldn't find anything they liked, they made their own!  Mine usually hit about mi 40, so bad I couldn't move, so I understand your pain! Good luck, keep "tweaking"...

S.

Other posts suggest more water, which is correct.  However, cramps could simply be lack of training miles.   A proper training plan with a gradual build up to longer and longer rides are needed.  During the long training rides, try alternatives for water, sport drinks and nutrition.   Keep a journal and note which combinations worked and which didn't with a corresponding note on the weather conditions.  You may find sports drinks with high carb solid foods may cause stomach upset.  Remember, your body can only absorb about 250 calories per hour, don't over eat.

For my first Ironman triathlon (bike segment is 112 miles), I hired a coach and he had me biking up to 200 miles per week throught the summer (race in Oct.) with a proper long term build up starting in January on the wind trainer.  He also had me seeking hills for medium distance rides.  

Good luck

Bob

You got some good advice but here's hopefully a little more. I carry one bottle of plain water and one bottle of (take your choice - athletic drink). Additionally, I set my watch timer so that it constantly goes off every 11 minutes. That is my cue to drink on a regular basis - not much but that way I don't forget. Additionally, I rotate the drinks so that i don't get filled up but yet stayed properly hydrated. It's become quite funny now as on a group ride my friends hear my timer go off and yell "drink time."  Also, remember that proper hydration starts about two days prior to your event so get plenty to drink the two days before you ride.