rakekay... when it's raining you will feel colder even if the temps are still fairly warm just because your skin is wet and you're moving... if you can find a rain jacket or vest that is waterproof it will help keep your core (lower back mainly) warm... If you don't need it roll it up as tight as you can, rubberband it and put it in your middle pocket of your jersey. As to getting lost... again thinking ahead for rain... ziploc bags! Carry your cell phone in a ziploc and also the ROUTE sheet in a ziploc! That way it stays dry... I rode all over Ireland last year with the maps in a ziploc and it worked out well...

if you are riding with friends, be sure you plan ahead in case you get separated... such as exchanging cell #'s and meeting up at SAG's... be sure you have (I keep mine in... a ziploc! LOL) a photcopy of your ID and medical insurance card in your seatbag as well... just in case... I've never needed mine yet, but if I ever do at least I know it's always there!

If it is colder than 60 degrees, be sure to wear a covering over your knees as well to protect the joint... either tights or knee warmers...

looking forward to hearing about your century! Rain or no rain I bet you'll have a great time... go get 'em!