Ebikes with front derailleurs border on being unicorns.
Yes, because with electric assist, we don't need to have just the perfect gear all the time, as we do with a purely mechanical bike.
Actually, I am surprised that we have progressed to bikes with so many gears. It's really unnecessary for most people. Schwinns in the 60s and 70s with a 5-speed rear cassette were fine for most people. Adding a front derailleur was an unnecessary complication, except for racers.
Realistically, once you have an electric motor you don't ride them with the power off. Since they are inherently so heavy, what you want to do is reduce the power assist to the point where the motor only makes up for all the extra weight and the bike feels like a bike again.
This isn't true for everyone, M@. You tend to favor heavy bikes, as you like the fat tires and the ability to carry a lot of stuff.
If the concern is about range anxiety, that is something you learn to deal with very quickly and fairly easily. You learn your limits and don't exceed them, because muscling a 45+ lb ebike home is always going to suck no matter what.
Yes, the range anxiety thing is a Catch-22: We can buy more
electric range with bigger batteries, but that makes the bike heavier and less "pedal-able". The other approach is to keep the bike light, with a minimal power system and efficient, high-pressure tires, so that when the battery DOES die, it's easier to pedal. Think of a road bike with a simple 36 V system. It might weigh 5-10 lbs. more than a "proper" road bike, and the electric is only used for hills and stiff headwinds. One could keep up with a peloton of fitter cyclists on a bike like this, or easily get home after the battery is depleted.
I was thinking if getting a dual-battery eMoped for my next bike, but they are priced about like gas scooters, which cost more in day-to-day operation, but there is no range anxiety ever. I'm thinking now of an electric road bike. Still pretty light, weaker power system, but so much more mechanically efficient that the range wouldn't ever be an issue.
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Back to the OP: don't worry about having 21 speeds. The typical 7 or 8 will be plenty. Focus more on the type of bike you want and on quality. As you point out, direct-to-consumer Chinese bikes with no support based in your home country can be a great value on paper, but you're likely to get bitten by something.
An example I like to use is my heybike Ranger: It had screeching brakes from the start. I reached out to them, they told me how to align them. Nothing I did would stop the screeching. Probably nothing THEY could do either. It was just poor quality componentry. Do look for name brand brakes, like Tektro.