Originally Posted by CK & AK

No, please dont assume

CBT can be taken at 16yrs & ride 50cc bike
CBT can be taken at 16+ too (many here have done that)
Full test can be taken at 17 plus.
Direct access can be taken at 21.

If the full test is taken at any age under 21 yrs, you are restricted to 33bhp for 2 years from date of test.
Therefore, a 17 or 18 year old, can pass their full test, ride anything (often choosing viffer or cbr 400) LEGALLY, PROVIDED it is restricted - and after 2 years (at 19 or 20) can ride any machine they like (or can afford)

Hope this helps?

C