Lots of good points in this discussion. Re' the comment that cyclists should know when they are exceeding 20 MPH, even without a speedometer - I completely agree. As some who both drives and cycles, as well as uses public transport, I think I have sufficient judgement to know what 20 MPH looks like when I'm on a bike. It doesn't need to be exact, but I think an experienced cyclist should know when they are doing 20 MPH or thereabouts. To me, it feels quite fast, and certainly as fast as I would want to go on a bike - I'm something of a cautious cyclist by today's standards. But this brings me to another point - slightly off track. From the late 1960s through to the early 1980s, my father was a train driver on London Underground's District Line. Many of us may remember the flared sided trains on the District Line that were built in the late 1930s, and then again from the late 40s to the early 1950s - they were used on the District until the early 1980s. They had no speedometer in the drivers' cab. Drivers were expected to use their judgement. A long time ago now - I'm sure Health and Safety would have a field day these days. But if Underground train drivers were able to judge a train's speed in a dark tunnel, I don't think it's too much to ask a cyclist to have an approximate judgement of their speed in Richmond Park or elsewhere.
David Beeney ● 84d