If you're riding a single speed bike and the chain regularly derails, then that definitely sounds like a chain tension or alignment problem.
Since it has a battery and the battery is (most likely) chargeable, a little loss of efficiency is inconsequential. On the other hand, having an actual physical chain on an electric bike seems indeed unnecessary - at least for less sporty applications, where things like "feel" or precise power delivery are not important. The end result will be a simpler, more reliable bike. Not to mention better looking.
A Tesla motor is 98.5% efficient, so a generator and motor combo being 93% efficient does not sound like a stretch.
2. If it's the rear derailleur, it may be bent (especially if your limit screws from step 1 are maxed out). You need a derailleur alignment gauge (or just take it to a shop) to verify.
Be careful when you do this so as to not apply too much power when you're trying to do this. If you're in a really high gear and it happens, you can get off, hold your rear tire off the ground and turn the pedals. Works 90% of the time unless you got your rear chain jammed between the cassette and the spoke.
Edit: You can very often see this if you watch professional bike racing. When the mechanics change a rear tire it will almost always knock the chain off of the front chainring. They'll just shift into the proper direct (low if it's off the high side and high if it's off the low side) and then spin the cranks and the chain will come back on.
You get the idea. At the leading edge, bicycles are already extremely complicated. If we're comparing this idea to a bicycle from 2002, it's complicated. But I'm not sure that it's that complicated compared to the kind of bike you'd find in the roof rack of an Audi S4 Wagon :-)
A high-end regular-bike has electronic shifting and a power meter and that's about it. And you're talking many thousands of dollars worth of road bike. It's like seeing a Ferrari or a Lambo rolling down city streets. They exist but they're rare.
I think it's reasonable to compare a leading edge technology to a leading-edge existing product. Otherwise, it's like it's 2007 and we're complaining that this newfangled iPhone thngie can run out of battery in a day, while my POTS telephone works even in a blackout.
Yes, true, but apples, oranges.
Which often have most of that and a chain too.
But also, e-bikes can let you ditch gears, which add complication.
But I think the main selling point is that you can seperate the sitting/cycling position from the driven wheel in interesting ways.
This is literally just get on and start pedaling and the bike figures out the rest. It even makes e-bike controls super easy, since you can just set a speed and start pedaling and it will supply just enough juice to make up the difference.
The obvious downside is that it's going to be less efficient than a chain drive, because nothing beats a chain drive. But if you basically get the benefits of an e-bike for free then the efficiency loss isn't a big deal for the rider.
It has a single gear, you can spin the pedals backwards to engage full regen, but the secret is that its usually doing a little regen which it stores and uses to help on hills and when accelerating from a standstill.
Maybe in other areas people are doing 60kph on bike trails or something, but that's not what I see around me. They seem to top out around 20kph or so, which makes them basically just bikes as far as traffic flow is concerned. Sure they will zoom past you on the uphills, but who cares? It's not hurting me or anybody else.
They must not have sold very many of them because Fallbrook-NuVinci went into chapeter 11 and enviolo bought the tech.
I've had this system in mind for years, I think for cargo bikes with long chains, this will be a clear winner.
You can expect to change the chain every 5000km. In theory a fully electric drivetrain could last forever.
Because if something goes wrong with your phone you probably won't be able to fix it. Compared to a bike where most anything can be repaired.