FF, sorry not sure about cycling/calories burned, try
MapMyRide.com - Map your Cycling, Compete against Lance in the Tour de France Challenge, Tour de France Maps, Bike Map and Mountain Biking Routes and join our Cycling Community of Cyclists. Cycling GPS for Cycling Social Network, iPhone, Topo Maps, E i use the sister website mapmyrun, it's really easy to use as you can create a training log. Then you map where you go, bit like google maps. You can enter how long it took you, your weight etc. and it works out how many calories you've burned. Plus you can save all your routes, so it makes keeping the training log really easy, and you can see how many calories you've burned in a month, and how far you've cycled!
AJB completely understand the dilemma, i've really upped my activity levels in the past few weeks and am looking forward to my weigh in on Thursday, but I know the weigh in could go two ways, either by increasing my activity i'll have lost more than usual, or my body will have gone into panic mode and i'll have lost less...will just have to wait and see! But like you said, it's better to be fit and healthy!