The simple philosophy is to celebrate, once a month, the freedom and fun of cycling without the fear that usually accompanies urban riding. In practice, this means a couple of hours where the cars of a city have to submit to the relaxed pace of a group of cyclists as the tables are turned on a habitually difficult relationship.
Critical Mass has no leaders and no set route. It is not an organised protest in the purest sense, but a gathering of cyclists who all happen to be riding the same way, in no particular hurry. This essential anarchy is at once makes Critical Mass such a beautiful, yet such a problematic thing. Not everyone who takes part is there for the same reasons as each other, which makes it hard to know whether a given Critical Mass will feel like a relaxed evening with friends or a tense experience under the eyes of the police, ever present at most cities' Critical Mass rides.
Predictably, there are delays for motorised traffic. On a good day, these delays are brief and everyone gets to where they are going. Smiles and waves are traded between cyclists, pedestrians and sometimes even motorists.
On a bad day, when the flow and 'buzz' of Critical Mass isn't working as well as it should, there is aggression, frayed tempers and legal problems. It's a shame, as this should be a celebration of positivity, not a chance for cyclists to alienate other road users.
January 2007's London CM was not the best in terms of atmosphere and interaction between riders, police and public. After a couple of hours, I no longer felt the ride was positive, so I rode off towards Stoke Newington where I knew Kate had a pint waiting for me.
But for the first hour or so after the mass of bikes set off from its customary meeting point at the National Theatre, it was a joy to be back in London on two wheels - not easy now that Southern Trains are enforcing their restrictive policy towards carriage of bikes.
The highlight of the evening was, without a doubt, the most amazing sound system I have ever seen on a Critical Mass ride. On Critical Mass it is usual to see a couple of speakers and a small amplifier lashed to a shopping bike, providing music to help create the ride's all-important sense of fun.
Occasionally, an enthusiast pushes the boat out, with a professional sound set-up mounted on a trailer or load carrier.
But Friday's ride was accompanied by the amazing sound of three load-carrying bikes, connected wirelessly, sharing seven speakers and a 3m towable 'sound cannon', filling the streets with music.
These brief videos give only a suggestion of the amazing atmosphere created by this impressive use of technology.
Links:
Critical Mass on Wikipedia
Critical Mass on Flickr
Critical Mass in London
Critical Mass in Brighton
AV2Hire - The guys behind the superb mobile sound system.