http://en.wikipedia.org/wiki/Ciclov%C3%ADa
The idea was started in Bogota, Colombia to help motivate people to go outside in a city that contained a lot of roadways and little park space. It's grown to a point where over 120km of roads are closed every Sunday in Bogota.
The problem with how it was decided to run it in Calgary was that they chose to hold it right beside one of the best cycle paths in the city, and it's so short, that there's really no reason for anyone who's using the pathways to leave the paths only to go back onto it a few blocks later.
If you look at a map of downtown Calgary, they chose to hold this at probably the worst location they could have. There is so much park space and extensive pathways in the immediate vicinity, that it's completely ridiculous to close a couple of blocks of Memorial for this event, which could easily be held on Prince's Island and the surrounding pathways.
It seems like someone saw a news story about the growing popularity of these Ciclovia events and thought, "we should do that in Calgary", without ever giving any thought as to why they're held in these other cities, if Calgary needs such a thing at all, and if we do, where the best place to hold it would be.
If it was decided that something like this would make sense in Calgary, they should have closed one or more of the north-south roads into downtown to make it easier for people to get to the very good pathways that already exist around Prince's Island, Eau Claire, and Kensington. A good road to choose would have been First St SW, close it from the area around the Talisman Centre and the Elbow River Pathway up to Riverfront Avenue, where it connects to the Bow River Pathway. They could have a Tai Chi demonstration in the park there by Chinatown, with other activities scattered around Prince's Island and Eau Claire. Calgary has the most extensive pathway systems in North America, with over 500km of paths and trails within the city limits. We don't need to close streets in order to create more paths, especially immediately beside better dedicated paths.