Rivian's TM-B electric bike

If that worked well though, why pack a large battery in the first place? My suspicion is that pedaling provides a small percentage of the energy needed to move you and the bike and your cargo.

A traditional bicycle chain drive is something around 98% efficient - particularly if you're using internally geared hubs or a single speed with the chain line perfectly straight. What's a typical consumer alternator efficiency? Maybe 85%? And then a few steps for losses in the charging circuit and then again at the motor.

Not even napkin math, but ballpark I would think you're looking at having to pedal about 20-25% harder to accelerate the same rate compared to a chain, with no supplemental energy directed towards charging the battery (though I would assume al the energy goes through the power management system anyways).

However you get some gain in that you don't have to select a gear ratio, and that the electric motor provides torque efficiently at any rpm you can realistically expect on a bicycle. If it has an adaptive resistance level it will probably be more work (energy) but for many non-cyclists feel much more intuitive and simple

Lance Armstrong can sustain about 450 watts. Rec cyclists maybe 1/4 that. E-bike motors are 250-500w. So not a small percentage but also not enough to be sustainable unless you are a world class athlete.

I think the idea is to disconnect pedaling from road conditions.

When you’re biking, it’s preferable to pedal in “safe” zones (protected bike lanes, trails etc.) while relying on the battery for eg intersections and when sharing the road with vehicles. With a regular bike you have to pedal harder precisely at these zones which makes it a little scary. You can also pedal on fairly flat ground/use all that energy to climb up a steep hill quickly without pedaling etc.

Are you doing a bit? I’m worried I’m about to be the joke ruiner :) The battery is included so you don’t have to pedal. When the battery is out, you can pedal. The only thing I can come up with is you think it is literally impossible or extremely difficult to pedal an e-bike when it is out of battery. it’s not fun but the incremental battery weight is as if you gained 20 lbs, not impossible.

Edit: oh I see above there’s subtle confusion building over the thread that this is a new feature of e-bikes, as of this Rivian marketing. it is not.

Exactly.

My government says the trigger (accelerator) is bad and made it illegal.

In usage, however, I feel WAY safer being able to accelerate (from standstill) through intersections. I once had a chain break at an inopportune moment while doing that - scary! Now my rear hub motor means there's no danger anymore.

charging by pedaling is just for range extension. obviously you aren’t breaking the laws of thermodynamics on an e-bike.

I'm pretty sure its regulatory. As long as the rider has to pedal to get the bike going, it isn't classed as a moped with restrictions on being used on trails and such. Yet having pedal power mix with electric assist power is complicated, so this might actually be an economy compromise.

Note that China, who doesn't have the same regulatory burdens we do, they got rid of pedal assisted e-bikes for their own market long ago because they make the unit more expensive and less functional (or you see pedals on some of them, but they are never used, most people use them with throttles only).

It depends on how fast or hilly the area you’re traveling, but either way, that’s kind of the whole point? If it didn’t it would just be a bike.

Wow. I assume you're being serious but it sounds like you shouldn't be on the roads. Stating that a trigger accelerator makes you feel "safer... there's no danger anymore" (not sure when the answer to bicycle safety is going faster...) doesn't help the rest of us.

I kinda agree with them. Being able to accelerate more like a car makes it easier/safer to merge with cars