I think I have cycled on all of the A1 to A5 in London, the A6 at various points, but certainly in Derbyshire and Cumbria, the A7 to escape Carlisle on Lejog, and the A9 up the east coast. A10, 11, 12 & 13 quite often in odd spots (the A13 is London Road, Westcliff, so it is no challenge at all this end). Not the A14, I think, but I have the A15, briefly. It’s nasty. A17 certainly, and for quite a while. Oh, and the A18 in N. Lincs. between Barnetby and Brigg. A19, don’t think so, but A20 certainly as it goes in and around Maidstone.