Motorcycles in your bus lane

Issue would be twofold I think- problem one would be enforcement as the chap on a motorbike doing 50 is already ignoring the limit, and two the bus company would resist strongly as they are targeted on punctual running.

if the motorbike doing 50 is already breaking the law then telling him he can't use the bus lane is a moot point anyway as he's quite clearly going to ride however he likes until he gets his collar-felt and pointed to the point of /being kept off the road. a 20 limit would actually help them throw the book at him if he's caught doing 50 as he'll be in greater excess of the speed limit and more likely to get a ban. for those who follow the rule of the road (albeit with some minor interpretations in their favour) may have their behaviour modified for the better if the speed limit was lower.

as for the buses, I'm merely basing this on my own experiences but the amount of time most buses spend doing more than 20mph is probably not as great as you may think unless it's on a major road. along my commute the buses stop every 50 yards and they're not quick off the mark either.

there's only been one instance in my own personal experience where I had a bus following me and I couldn't go fast enough to stay ahead of him until the next stop so I was holding him up and pulled over to let him pass. he was travelling empty with the lights off though so I guess he was on his way back to the depot in new cross to get home/have his tea.