If you are under 24 years of age, and you want to get onto a bike larger than 125cc then you are restricted to having an A2 licence. It is possible to get an A2 license at the age of 19 or over, by having an A1 license for 2 years. The rules are a bit convoluted.
This website was created in response to these new licence rules. It takes a bit of research to understand what you can and cannot ride with your restricted A2 licence. The basic rules are as follows:
You can ride a motorcycle without a restrictor if...
The power output is 46.6bhp (35kw) or less
Has a power to weight ratio of no more than 268.2bhp per tonne (0.2kw/kg)
Ride a motorcycle more powerful than 46.6bhp / 35kw
The bike cannot be restricted by more than 50%, so this this means the most powerful bike you are able to restrict down to 35kw is 93.2bhp / 70kw.
Has a power to weight ratio after restriction has to be no more than 268.2bhp per tonne (0.2kw/kg)