Was riding in Bromley (which is in London, so this might just be the rules for London) yesterday. We were stopped by 2 pscos. They were nice enough, said they weren't gonna fine us this time, but, the rules are: If you're over 18 and you're caught riding on the pavement you should be given a £30 fine (probably to their discretion). If you're under 18, you're given an E something something, which is basically a policy so you have to do some community service (they said, basically pick up a paintbrush). Now, if the group consists of quite a few ages (in our case, it was 2 over 18s and an under 18), because the under 18 person was present, the lot of us would have to do community service. Not sure if that changes with the ratio of overs:unders though. So yeah, nothing about wheel size.