London was closed as they were rebuilding the BMX arena as it was apparently the features were too big for the public, additionally they ere building a road circuit down their, I know the road circuit is open and they race and train on it now, it can hold around a national field (140 riders). The velodrome has been open but just not too the general public - all gb athletes were given the chance and some who helped on the build I think. They have had events on it e.g. The Revolution Series. But it is now open to the public, it's costs considerably more than manchester though.