I did it on my cross bike (with slicks) one year – normally take a bog standard road bike though. You see people on all sorts of things, of all sorts of vintages, so just take something that isn’t going to fall apart with a bit of vibration 🙂
The saturday route used to be more or less the same as the race route, but with a bit of cycle path action in places. Now that there are finishing circuits that repeat some of the hellingen, it is a bit different (not bothered to actually look at the differences).
I’ll be there on the 134km ride, ti Serotta, pink and blue JMJ Cycles jersey if the weather is nice!