im a type I diabetic also, and i just recently started on longer rides. im actually training for the tour de cure in may!
ive found that if i eat 40-50 carbs per for each hour i ride my levels stay very well in check. i also carry cliff bars with me to snack on if i feel like i need to. i keep my pump on though, and havent scaled back the basal rates, but as i go on longer rides and farther from home i will probably end up doing that just to be safe. my longest rides so far have been 35 miles or so, so im sure i'll have to do some more adjusting when i work up to longer rides.