I love ebikes and generally like what Rivian does, but in a very competitive market it's hard to see the appeal of this.
Bikes are simple for a reason, they're light for a reason, they are maintainable for a reason, their ergonomics have been refined over decades, and so on.
I don't think non-bike companies shouldn't have a crack, it's fun to see new takes on it all, but bikes have been "disrupted" already by a dozen different forms of transport, they stick around in their current form because it fits well into the gaps the other modes leave. There's no big new problems to solve with the bicycle aspect, just pop your cool drivetrain into a regular bike and you at least get to keep the broader market of cyclists as customers.
1. https://a2zcalculators.com/science-and-engineering-calculato...
Even a floor of 100W would rule out smaller/less athletic riders.
Even 50W is a fairly significant boost for casual riding.
You don't need to sustain 250W pedalling.
What is the end-to-end efficiency of the generator, electronics, and motor combination? If it's 75% efficient, then you need to pedal 33% harder than normal[1]. If it's 66% efficient, then you pedal 50% harder.
Unfortunately, I can't find real data, so those efficiency numbers are guesstimates. Electric motors and generators can be very efficient, and I would hope that they'd use efficient ones for an application like an ebike.
As a point of reference, pumped hydro can be 70-80% efficient[2], and that involves a motor, a generator, and mechanical losses. That's not an apples to apples comparison, though.
---
[1] Where normal means a 100%-efficient link between pedals and wheel. Actual bike chains aren't, but they appear to be 95% or more.
[2] https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...
1: https://leginfo.legislature.ca.gov/faces/codes_displaySectio... (312.5.c)
Maybe you pedal the generator on the kickstand for a minute to give it enough charge to operate the electronics, and then away you go working hard like on any other e-bike that's out of charge? I don't see why it couldn't move.
Once I put myself onto the bike I don't care all that much whether it's 15lb or 50lb.
This is a really dumb thing to say; it makes absolutely no sense. ALso you typically don't "put yourself onto the bike" but rather pedal it.
I'm not talking about pedaling, I'm talking about sitting. Because now my weight combines with the bike. The difference between 215 and 250 pounds is not that impactful.
Edit: There are some differences in weight distribution, but I clearly don't mind those because they exist while the bike is powered too. The issue at hand is the pedaling, and that depends on total weight.
As in, if not for those problems you would keep riding and not push it.
So my response is that you should just fix the gearing (or buy one with good gearing), and 50lb isn't an issue for riding.
So both issues are resolved, and you could keep riding a normal design just fine. This means the design of the Rivian is a real detriment.
And if anyone said "lets ride motorbikes with pedestrians" they'd be looked at funny.
I'm seeing more near misses each week AND in 20 years I'll be old enough to feel real vulnerable...
and mass!
Some of these electric bikes are quite speedy - capable of mixing it up with flowing traffic. So classify them as being motorbikes.
If they can't go that fast, or are "assistive only" (require large fraction of rider pedal input up to a set speed) then legislatively they are a "normal bike".
The thing is, we already have the rules around each style of bike. It's just a classification thing.
Many electric bikes are masquerading and hoping no one looks too closely. So, just look closely. And hold actions responsible.
Yes, and people who are slower and more fragile and take longer to heal are more so than others.
Eyyyyyyy
Because some designer wants to feel good about themselves, better than all who came before.
This "revolutionary design" does not offer any significant advantage over the existing systems for e-bikes. A regular e-bike without power is a just a regular bike. You can adapt a regular bike into an e-bike for < $600. Any run-of-the-mill mechanic can figure out how to work on a basic bike. This one will probably require some "certified Rivian expert" to work on it.
Only irrational neomania can justify being interested in this "revolution".
The bike won't fit any of that until there's hot swappable batteries sold everywhere, and when it's dead you'll be pushing it back home.
Also, 100 miles is a lot on a bike. I think they got rid of this design requirement by just making the range longer.
"It features a new pedal-by-wire drivetrain called “DreamRide” developed in-house. The rider pedals a generator, which replenishes the battery,"
So uh, keep peddling?
Yes, the motion->electric->motion circuit is not as efficient as direct pedal but you are explicitly not stranded.
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
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.
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.
Oh, and it’s a serious crime if I cause an accident and try to flee.
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.
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).