I am considering sprinting but as a newcomer I am having difficulty in interpreting the regulations for next year. In the blue book it states that I need a rollbar/cage as specified in Cc 31-35 or 36 as appropriate. My caterham has a 1600cc engine (i.e. less than 2000cc) so rule Cc31 states that I need a roll bar as in diagrams 1 or 2. This applies to production and modified classes equally so why are clubs introducing a rule that states that you need a rollcage if you run 1b tyres and are therefore in a modified class even when you have less than 2000cc?