coasting 

http://live2010.bikeradar.com/news/s...ts-and-report/

take a look at tthe results of this sportive. i did this couple weekends ago and it was my first one too. I don't know how hilly the one you are doing is meant to be but this was surprisingly hilly and a lot of people i spoke to during and afterwards said it was harder than others they had done and for the location they didn't think it would be hilly. they planned the route using the north downs up and down several times to get the climbing in.

I rode (well attended with..we never rode anywhere near each other) with a serious and experienced cyclist and he had just been on a holiday training in mountains in teneriff. he said it was a tough ride. Anyway, i say this so you can get an idea of the difficulty of the ride so you can look at the finish times in some context. we did just under 7,000 ft of climbing according to many cycle computers despite that mapmyride says.


chasm has good advice and i cant add more to it. I would however say do the 100. the 50 will leave you thinking you could have done a lot more especially if you are a fit marathon runner.