Glad you're out there!
I'm type 1 and a cyclist too and starting training for the Edinburgh Marathon in June 2006 also. Always take a pack of glucose tablets with me on any cycle over 40 miles. Don't know how the long training runs for the marathon will affect me yet but, so far, the 7-8 mile runs make the insulin I inject work a whole lot more efficiently. I have to either eat quite a bit more or reduce my dosages to suit.
I think I might recruit some help on race day to pass me my testing kit unless the training schedule glucose measurements follow a very predictble pattern.
Is it too time consuming to do a bg test on the changeovers?