It is very difficult to come up with an infrastructure that allows cycling and walking to flourish. Examination of failure is necessary - here's a look at some issues in London.
The other element of a bike-friendly city is less about bulldozers and big projects and more about subtle changes. As such it’s much easier to get wrong or to half do. It involves making smaller roads, especially residential streets, more oriented around humans (whether on bikes or walking) than around motor vehicles.
Part of this is speed reduction. If bikes are to share the road space with cars, then the cars must be going at no more than 20mph. This can be hard. It’s also – and this is the really tricky bit – about making it more difficult to drive. Doing this involves cutting off rat runs using bike-permeable dead-ends or one-way routes. The Dutch are very good at such schemes. In many places a trip which might take five minutes on a bike could take three times as long in a car. And so people tend to not use cars unless it’s necessary.
This is hugely politically difficult, because car owners tend to object very noisily to such measures. To create effective quietways you need political vision and courage. And this is often lacking.
Yet think of what many of the actual stops are for. Not speeding or moving violations, but for vehicles out-of-perfect-order. The broken taillight is illustrative. How many lives have been saved by traffic stops who informed the drivers of vehicles that one of their brake lights is out?* I could not find a peer-reviewed article on whether broken taillight enforcement is effective in increasing safety. No one has felt it worthy of study in the traffic safety community. The broken taillight does show up as an issue of pretext, the legally protected excuse law enforcement gives to pull someone over because they want to inspect the vehicle or the occupants.
Clearly we want cars with working taillights. Minnesota law requires 2 working stop lights for cars manufactured after 1960 (but not for motorcycles). But this is also not a high priority. If we actually cared about taillights, there is an alternative scenario. Police (or better a machine) could have just photographed the car and mailed a fine to the address on record of the owner of the car, which would hold up annual registration if not paid and if no proof of repair provided. The car would eventually get fixed.
Instead, we have the scenario, which if it had gone well, finds the driver (not necessarily the owner) gets a stern lecture and a fine. There is no actual guarantee of the repair.
But if we cared about traffic safety the time and resources the police spend on harassing vehicles with broken taillights could be spent on something more serious: actual drunk drivers, actual speeders, actual red-light runners. The evidence argues this was not about traffic safety.
There have been dozens of micromobility attempts like this. On paper their high efficiency of moving people around - often at low cost with a minimum of pollution and noise, but a fundamental problem is they often are a poor fit into an existing infrastructure and expectations. I wouldn't be surprised to see vehicles like this emerge in city cores as regular cars are banned - we're seeing the beginnings of that in some European cities now.
The Guardian on Germany's bicycle highway. Not easy or cheap to get right as many things, including culture and existing infrastructure, have to fit. The Netherlands and Denmark have a growing expertise and represent somewhat different approaches. The link to a piece on Groningen's success is interesting.
The company is looking for investors, but the idea is very simple - a friction drive assist. Given the cost it would probably retail at $300 to $400. I'm a bit skeptical how well a friction drive would hold up and how it would work on wet days, but a simple design...
The authors of “Cycling Cities” describe the “fine meshed” cycle networks of the Netherlands in towns such as Houten but it may surprise many “Go Dutch” advocates that central Amsterdam has fewer cycle lanes than often perceived (although those that exist are wonderful, such as the one that goes through the Rijksmuseum). On a photograph of a classic Dutch bike on a cycleway a caption in the book describes the scene as an “Amsterdam rarity: strictly separated bicycle lanes.” Amsterdam has high cycle usage, says the book, because motoring was discouraged by traffic calming and “reducing automobility” by making car parking expensive or fiendishly difficult.
Curiously titanium is cheaper than aluminum or stainless steel for the purpose - print time dominates cost. Lugs are printed and then welded to titanium tubes. The design hasn't been ridden, but is interesting. Carbon fiber dominates high end cycling, but many the "feel" of the frame is lacking compared to the best steel and titanium frame bikes.