I did my bike marathon - it wasn't easy, but manageable; definitely noticed the elevation. I couldn't sleep half the night from a mixture of elevation, nervousness and the church steeple banging its bells every 15 minutes all night.

It started off chilly, even foggy, then crossing over the second pass it got sunny - that's the alps for you. I did pass some people on the climbs, "real" men too, that was rather satisfying
The second 50 km was mostly downhill or flat, so with boyfriend setting the speed we managed a 23 kph average, that's under 14 mph but still faster than ever. The competitive atmosphere does push you a little I guess.
Got home totally knackered, feeling dehydrated and headachy - the speed and elevation pretty much did me in.

We were at the very back of the pack and what was really annoying was the food at the support stations... There were only apples and oranges left at # 1, just before the two major climbs. That was just not enough. There were NO bars available, although the power bar logo advertised in the flyer at every station. At least some bananas were left at station #2, and cake and sandwiches at the end. They gave us a power bar and gel with the starter pack, but for 40 bucks signup fee that was just not right. I don't really care to pay for a cheapo jersey, two bars and a couple of apples, and still have to deal with cars passing.
Plus standing in line for an hour to get the starter pack the night before. That was ridiculous, when they could just have sent it by mail.

Anyway, I don't know if I will go to another one because I don't care for a ranking.