Hi Simps and everyone,
Sorry for the late reply - have been very busy and not logged on for ages, but this thread caught my attention as cycling is my main hobby (for fun, only v rarely competitively).
Some really good advice already from the others. What kind of insulin regime are you on? THe pump has really helped my control whilst exercising (although still a lot of room for improvement!). The pump allows me to change basal rates (rather than just eating) for exercise. Previously I would have just taken on extra carbs and/or reduced insulin at previous meal time. Having said that, I still have to be very mindful of the last meal bolus, as if insulin from the last meal time is still working it tends to spend me spiralling down pretty quickly!
I thought it might be useful to share what I currently do as it depends a lot on type and intensity of cycling.
Short road bike - <90 mins, 30-40% basal, sip water
Long road bike - 40-50% basal, sipping energy drink (10-15g carb/hr), water and electrolytes for hydration (ie two bottles, as Copepod suggested).
XC Mountain biking - usually several hours at a time. 30-50% basal depending on intensity with jelly babies/cereal bars as necessary, electrolyte drink
It's tough though and somedays it just doesn't work. I hate having to stop to test when riding in a peleton as it is almost impossible to catch up and/or inconvenient to the others if you make everyone stop (currently looking into using a sensor or has anyone any tips about testing on the move?!). Mountain biking is easier as mountain bikers stop and faff more! Having said that, adrenaline makes a huge difference to me and I find it hard when there are long stretches of up or down. Or when using lifts and only doing downhill (had great fun in french alps with chair lifts this summer). As the others have said I always carry a lot of extra carbs just in case and when correcting highs I only use 30-50% if my usual dose if still exercising.
I am a big fan of electrolyte tablets that have zero carbs (like nuun). I used to cramp a lot, especially if my BGs were or had been high, but feel these definitely help.
Anyway, would be interested to hear how you get on and am interested to hear what others do too. The london to paris is meant to be a good ride. Last year I did john o'groats to lands end (965 miles) in 9 days, but this year I've been mainly mountain biking.
Oh and one more thing, have you heard of team type 1
http://www.teamtype1.org/ Inspirational stuff