Ride London is a fantastic sportive that every cyclist should ride at least once (or several times if you are lucky enough to get a place!) Who doesn't want to ride on closed roads for a change? Riding past famous monuments and finishing on The Mall are fantastic moments (only wish I had rigged up my Go Pro for the ride.)
The route is very fast (and mostly flat) and very well marshalled with plenty of toilets, aid stations and food/drink stations. Brilliant atmosphere and a great days riding.
The main downside is the logistics of getting to/from the event unless you live very locally. I (like many others) parked at the O2 and Ride London help arrange pre-bookings in advance. We were told there would be signage directing us from the O2 to the Olympic Park but there wasn't any. This added a certain amount of worry which could have been avoided (only 5 miles but if you don't know the way it's an added complication especially after a very early start/drive to London etc.) Getting home was also tricky as we had to navigate 10 miles of London traffic/tourists on busy roads. Not a massive problem but be aware. Also, you must go into London on one of three days before the event to register which can be a hassle for people who don't live in London.
One final word of warning, there have been nasty accidents every year and the climb up Leith Hill was a little awkward as so many people were walking and things got very bunched (with certain riders getting annoyed and trying to go through gaps that weren't really big enough.) I saw several nasty accidents (one guy crashed before we even started!) two guys crashed in front of me as they raced for the line on The Mall and I saw someone being stretchered into an ambulance wearing a neck brace. Unfortunately another person hit a tree and needed an air ambulance. Perhaps there are too many people or perhaps people get over excited by decents on closed roads but it seems to happen every year. Really hope everyone makes a speedy recovery.
Anyway, a fantastic ride and one every cyclist should do at least once. There really is nothing like riding on closed roads and the support from people watching was amazing - flying through towns and villages lined by people really is something very special.