We get those (CBR125's).

UK licence setup;

CBT, compulsory basic training best part of a morning sent riding round cones then a couple of hours on road instruction. Really it's for kids who have no road sense but everyone must do it

You can now ride a "bike" up to 125cc and 15bhp for two years on L plates, this market in the UK is massive, every other kid has a 125 scooter if he's 17 or a 50 if he's 16 (50cc and 3.5 bhp is the max if you're 16, it's called a moped still).

In this two year timeframe you have two real options

Direct access training and test on a bike over 45bhp, then ride anything (over 21's only)

Normal route traing and test on a 125, then ride a bike under 33bhp for 2 years, then ride anything, kits can be got to make just about anything 33bhp.

There's also an a2 licence and test which restricts you to a 125 for ever, why you would follow this I have no idea.

Better breakdown here
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