Staged (progressive) Access
If you want to progress to bigger bikes, there’s a simple path to follow - 'Staged Access'. The first part is the CBT, which grants you the ability to ride a motorbike of up to 125cc from the age of 17 years. Riders can then take an A1 theory and practical test.
Once you've had had this licence for two years, you can take the A2 licence which covers bikes of up to 47bhp. For unrestricted access to the biggest bikes you must be 21 years of age and have held an A2 licence for at least two years.
It sounds complicated but the idea behind it is simple: riders need to build up their skills slowly, gaining experience on smaller engine bikes until they move on to more powerful machines.