As Dave said, no problem with 20 mph past schools during school time. But on good A roads WHY? I have now adopted setting the speed limiter at 20 mph, as trying to maintain 20 mph requires constantly checking the speedo, with eyes not being focused on the road ahead, definitely not great for safe driving. Yes there is always someone up your rear, but I just ignore them when in the car, but accepted it's far from ideal when on a motorcycle. Fortunately I don't have any need to use 20 mph roads in my area when on a bike.