From the International Kicksled and Scooter Assocation (sic):
In November 2011 the active footbike countries (within IKSA) decided to talk about adding a master category in to footbike race competition. On the moment we see more racers in the older categories coming in our sport. The speed differents between someone of 40 and 50 years old can be large. To garuantee a certain level of competition we need to monitor this seriously.
Becaus the added master category will mean a change for some in our sport the countries decided to embed it not earlier then January 2013. So coming summer in 2012 the categories used during footbike races stay as they are and then in 2013 we upgrade it.
The Master category (40 years old to 49) will be inserted between the Seniors (to become 18-39) and Veterans (to become 50+).
Age charts and more information are here.