I recently visited London and had a chance to ride one of the chainless bikes distributed around London. Currently in a pilot phase, this self-service bike station program has placed hundreds of chainless bikes using Dynamic's shaft drive system in about 50 locations in and around London. It's pretty cool. You walk up to the station, use your cell phone to call the phone number on the station, enter some information on the keypad and the station's locking system unlock's the bike for your use. You ride it where you need to go, then re-lock it into another bike station. The first hour is free, after that it's a nominal charge billed to your cell phone. This system is similar to the very large-scale bike station program recently implemented in Paris, dubbed Velib, now with more than 10,000 bikes and 750 stations. One of the key aspects learned from this London implementation and proven in the Paris implementation is the concept of "critical mass density". Through this pilot program and subsequent interviews and focus groups of those who did and did not use the system, the "critical mass density" theory emerged. It was deduced that the bike stations needed to be placed no more than 1000 feet apart, thus creating a density of bikes to the point where convenience and mass usage would pass the tipping point. This was the theory behind Paris' bold implementation. It has proven correct. The volume of usage of the bikes is very high, as much as 15 rides per bike, per day. This equals 150,000 riders per day on the bikes. As more and more cities evaluate these types of systems, chainless technology will undoutedly be part one of the technologies considered.