The internet disagrees http://www.astounding.org.uk/ian/cyclelaw/speed_limits.html I understand that Richmond Park has some kind of byelaw that allows the parks police to issue fines for speeding bicycles but other than that it would have to be some kind of reckless cycling charge rather than speeding.
I have no way of knowing how fast I’m riding my bike without doing an on-the-fly calculation based on gear inches and pedal rpm.
I live in Dunstable and we were hit with a blanket 20mph speed limit on all but major roads, it’s ridiculous, IMO 20mph is way too slow, I agree in roads with schools or playgrounds but a blanket limit is stupid, I have found that people now drive at 30mph and not much more, I reckon it’s their backwards way of getting people to stick to the original limit!
I read somewhere - about a year ago when the City announced that it was going 20mph - that the Met had ‘no plans’ for 20mph enforcement… obviously that has changed as Monkimark says , however I thought it was refreshingly pragmatic of the Met, it seemed to be saying that they had better things to do… (and also inferred that the Met considered 20mph blanket enforcement a bit silly and definitely something that would unnecessarily upset the general public .
I would guess that (not counting outside schools and small fully residential streets where 20mph speed bumps enfore it anyway ) it is generally seen as a silly limit introduced for political rather than practical reasons (especially since it operates all though the night when kiddywinkies are all tucked up in bed and there are few, if any pedestrians or cyclists about ),
Therefore ‘cracking down’ on it would be a bad move for Police PR…