donn said:
Cephalotus said:
Problem is if an accident happens because there is no insurance. So if you hurt someone badly costs can go into 100.000nds of Euro, even above 1 million.
You have to pay that out of your own pocket. This is very bad either for you and for those person you did hurt.
I assume the concept of insurance is seen different in EU and US, it's more a cultural thing. People here expect that life threatening things are insured, no matter if health related or accident related.
Hard to say, without knowing anything about the laws that govern this and how they're handled in actual cases. (And it doesn't help that I'm no lawyer at all, but ...)
In my state, there's a rather well developed concept of motor vehicle liability, and of course a well worn path to its application. As far as I can tell, there is no such specific legal basis for liability with electric motor powered bicycles, and there's little if any (?) case law. Here, electric bicycles (classes 1, 2 and 3) are explicitly categorized as "bicycles" (RCW 46.04.071), and I can't find anything in there that puts bicycles in any special category for liability. So apparently, in terms of liability, an ebike would have the same kind of liability as any bicycle, or for that matter a pedestrian or a roller skater. I don't think that means "no liability", but you'd need to look at case law to understand how it would typically play out.
It would be interesting to know if there's a lot of actual cases in Europe, given the several hundred thousand illegally modified ebikes in Germany alone.
Basic bike...no electrics at all...run into someone. They are going to be hurt. This is just physics at work. Slow moving object hit by faster moving object. Faster moving object transfers it's speed and momentum to slower moving object. A motor doesn't change this in any way...other than maybe making the impact happen at higher speeds.
Never mind this thread is about hub motors dying off.
What's bad about hub motors:
1. Cost: They are more than a typical inrunner or outrunner of the same power.
2. Weight: They are really heavy and found inside your wheel where there is no suspension. This is the worst location for a large mass. An inrunner or outrunner can be mounted inside the suspension and of course they weigh far less so all around a hub is a poor choice for weight and suspension.
3. Spinning mass: Inrunners are best in this regard, then axial flux, outrunners and finally hubs are the worst. Spinning mass is a loss. It takes power to get it moving. While regen helps a tiny bit in this regard, it's a really small gain compared to the losses for making that mass spin up. This effects acceleration too as more energy is required to spin up the motor instead of making you go faster.
4. Cooling: Some will disagree, but I think outrunners do best since they are open and cooling is easily achieved with a radial fan on the bell. Inrunners since they have the stator mounted to the motor shell can dump heat through the shell. Axial flux can be as good as an inrunner or a little better than a hub depending on the stator design and location. Last place is hub motors with a nearly completely isolated stator and almost no way for heat to escape the stator.
5. Phase resistance from motor wiring: Phase resistance is lowest in the shortest series length. Outrunners and axial flux motors are best since they are almost always wired delta. Inrunners are almost always wired WYE. Hubs are usually wired WYE. Delta is a single phase connecting to the controller. WYE is 2 phases in series connected to the controller. Less resistance = less heat. 2 phases in series = 2X more resistance than a single phase or 2X more heat.
6. KV related phase resistance: High KV means less turns of wire per tooth. I have an outrunner I'm winding for 80kv and 12 stator teeth. It needs 18 feet of wire to wind a phase. I also have a 12 tooth hub I am rewinding for 8KV. It needs 60 feet of wire per phase. Both are wound with 20 awg wire which is 10.15 ohms per 1000 feet. The hub can take 3 strands and the outrunner 10 strands. Just length of wire alone for a single strand, the outrunner will have 3.33X LESS resistance than the hub. Then 3.33X less again thanks to 10 strands vs 3 strands. Resistance = heat.
7. Mid drives (outrunners and inrunners): Thanks to gearing, tend to stay in their mid to high band of motor RPM's a lot more often where the motor runs best. A typical mid drive motor is turning something like 2000-4000RPMs. Hubs...you grunt from a dead stop and then never reach more than a few hundred RPM.
What's good about a hub motor:
1. Easy installation: Mount a tire, wire it up and you are done.
2. Compared to any mid-drive option: You don't need gearing, chain, belts and sprockets. These items add cost and complexity.
3. Quiet...no belt or chain or sprockets to make noise.
4. Cheap and easy for EV makers and DIYers to install.
5. Implementing regen is super easy, just use a controller that supports it.
After all of those compelling reasons for using a mid-drive with an inrunner or outrunner, why should hub motors exist at all? As it turns out, a lot of people don't want or even know they can do better with a mid-drive solution. They hear you need to maintain a mid-drive (lube the chain) and are immediately turned off. They hear "more complex" and are immediately turned off. It basically comes down to market demand and laziness IMHO.
Otherwise a mid-drive option of any kind destroys hubs.
