Spitting into the wind, as I so regularly post in here, it is never ever going to happen for a myriad of reasons. Chief among those are the following:
The present law is nearly a world standard outside of the USA and to a limited degree Canada where they are federated countries with State laws which are often worse than ours anyway.
Politicians and civil servants hate risks so prefer to stick with what most do for safety.
Most of the world cycles far slower than we in the UK do. From the Netherlands to Africa, India, China and Japan, cyclists amble along as low as half our UK common speeds, so to them a 15 mph assist is plenty. Belting around at 20 mph or more, grim faced, helmeted and often low over drop bars as if competing in the Tour de France is a peculiarly British cycling obsession. Almost everywhere else, cycling is just transport.
Speed limits in the UK have long been on a downward trajectory and changes are generally reductions. At one time in my earlier life we only had a 30 mph limit in built up areas and any speed you like almost everywhere else. Now look at it, 60 mph national limit with 70 only on some dual carriageways. Vast areas of the country limited to 40 mph. Whole boroughs with a 20mph limit, speed bumps everywhere.
And it's paid off, we have the lowest accident and death rates in the world by a huge margin. Thats why any talk of raising any speed limit is frowned upon, even with bikes, as the refusal to accept the S class high speed pedelecs shows.
Finally the L1e-A class of powered bicycle with pedals is limited to the same 15.5 mph assist and subject to registration with number plate and insurance. Everything faster is treated the same way and has to have a driving licence with CBT. So there is no way our bureauracy free pedelecs will be allowed more assist speed.
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Flecc, my point isn't so much do do with the legal max speed, it is that
we want to comply with the law, but the vast, vast majority of the equipment out there (including complete bikes, not just kits) is non compliant, so it's almost impossible to be within the law as it stands.
That said, 15.5 mph as a max speed is, IMO dangerous. It puts you in what I call "The cycle death zone".
This comes from decades of experience. The problem is our car centred society and cyclists having to compete with cars and so you have to dice with death every metre of your journey. Below about 13 mph and to cars you are just a quicker than normal pedestrian and they can zoom past easily and not feel hindered.
Over 20 mph and you are part of the traffic flow. Cars have more of a tendency to treat you as part of the traffic and not feel overly inconvenienced.
However from 13 to 20 mph, it is difficult for cars to get past you without exceeding the speed limit, but your speed is not fast enough for them to feel comfortable sitting behind you. It pushes motorists into dangerous overtaking manoeuvres.
Average cycling speeds in other countries tend to be lower than 15.5 mph, but there are reasons for that. In Japan they cycle almost exclusively on the pavement and share the space with pedestrians. In the Netherlands we look with amazement at how thousands of people can be carried across a traffic junction in minutes as they ride their bikes. We marvel at the efficiency and balletic performance of it all and think how awfully congested their streets would be if all those people were in cars. However, to the locals, it is awful. They want to get where they are going and not have all these people in the way so they can cycle at a decent speed
On the dedicated cycle tracks outside of town speeds are far higher.
I'm not convinced that average speeds in this country are significantly higher than anywhere else, if they are, it's because we have a system where we need to compete with cars. However speeds > 15.5 mph are not only the reserve of high performance athletes riding high performance bikes and wearing Lycra. A modern bicycle on the flat will roll along at more than 15.5 mph with minimal effort. Most average people who cycle regularly on a modern unassisted bike will average between 16 and 18 mph on the flat and hit 20+ mph at times. Fit riders will do even more. The speed riders you mention will be travelling at 25 to 30 mph, not 20
At the end of the day, for the sake of our health and the environment, we need to get people commuting by bike not car. Electric bikes are a game changer in motivating people to get out of their cars. Yet, we limit them to impractically low speeds. In my mind, the limit for assistance should be 20 mph, but there shouldn't be any shared cycle lanes, only dedicated cycle infra. Also, all speed limits on urban roads should be reduced to 20 mph, so there is a level playing field and a far safer and more social use of space.
At the heart of the problem is the way that town planners look at cyclists as some form of pedestrian. However, they should never be mixed. Even at 10 mph, cyclists should not be anywhere near pedestrians.