Rivian's TM-B electric bike

So the interesting thing about this is the ... peddle-by-wire drivetrain? So unlike a normal e-bike, when its battery dies it turns into a stationary bike.

I love ebikes and generally like what Rivian does, but in a very competitive market it's hard to see the appeal of this.

If I may also peddle my opinion, this e-bike is a fresh innovation and it's easy to see how revolutionary it is. What very competitive market has regen, 180 newton-meter of torque, programmable power curve, shape-shifting? This e-bike is incredible. These days, who lets their iphone battery die?

> a pun

Eyyyyyyy

Why should we care for "revolutionary" when the design that has been working for centuries is cheap, widely understood and universally available?

Wow I can't tell if you're being sarcastic. If so then nicely done. If not then bro do you even bike?

A phone can get charged with random 5V outlets and you can walk around with a 200g battery to make it last two days.

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.

When it's dead, you can order an UberXL and toss this in the back? Cheaper than a tow truck...

Also, 100 miles is a lot on a bike. I think they got rid of this design requirement by just making the range longer.

> Why should we care for "revolutionary" when the design that has been working for centuries is cheap, widely understood and universally available?

Because some designer wants to feel good about themselves, better than all who came before.

If wankery is what they they are after, maybe they should go design "revolutionary" sex toys.

Horses complained about this when the Model T came.

Just don't think of it as an e-bike.. Think of it as an electric scooter with a built-in, manual charging solution. The question then seems to be how well it compares against other electric scooters?

You could lean up against something and pedal to get a bit of charge back in the battery, then you just need to pedal it home like a regular dead e-bike, no?

> So unlike a normal e-bike, when its battery dies it turns into a stationary bike.

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.

"E-bikes" are much more efficient than electric cars, but they're just electric scooters with governors at this point, and only called "bikes" for regulatory reasons.

In the next sentence:

"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.

I don't think the pedals are attached to the drivetrain. They look like they are literally just to charge the battery. So this bike is just dead when it's out of batteries? Unless I'm missing something.

I have a friend who hates any electric bike not "pedal-assist". His opinion is they are electric motorbikes - that happen to have pedals as a backup option, usually not used.

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...

I would hope they designed it where you can keep riding. It seems possible. Pick some charge level (say 20%) and provide less and less power assist as you approach that. Once you hit 20%, a control system tries to keep it about 20% charged. Basically you enter a mode where the battery becomes a buffer (between the pedal and wheels) rather than a power source. The bike would feel sluggish, but it wouldn't stop working.

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.

Horses were not cheap nor universally available. And cars had the obvious benefit that they did not leave literal horse shit around the city.

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".

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.

Everyone is vulnerable regardless of age. There absolutely need to be regulations around how these ebikes are allowed to go based on their power output.

Maybe they figure you pedal to charge it up before it’d go again -like a windup torch. It’s energy wasteful but who knows what marketing forced the engineers to do.

> based on their power output.

and mass!

You'd have to pedal rather hard (equivalent of riding 21.7 mph) to provide 250W of power[1], which is the minimum for most ebike motors.

1. https://a2zcalculators.com/science-and-engineering-calculato...

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.

When a normal ebike dies you are left with a 50-60lb bike probably not with the gearing you’d want.

an emtb with the assist off feels like you’re pedaling out of a black hole.

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

I ride a motorbike. I'd argue speed is the limiter.

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.

This is an electric motorcycle with pedals. The presence of pedals that only-technically contribute to motion is a regulatory-dodge not an intended feature.

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).

That’s still a pretty huge gap from 50lbs of dead weight. This is a horrible and expensive ebike idk why HN is trying to defend it.

Well then the normal ebike should spend another pound to add better gearing.

Once I put myself onto the bike I don't care all that much whether it's 15lb or 50lb.

As long as it only moves if you're peddling, it passes the regulatory test.

Okay but cars first obviously, right? Considering they kill orders of magnitude more people.

Yes, it should be illegal to drive cars on sidewalks, too.

You might be stunned at what the boffins have come up with. Or perhaps horrified.

> Everyone is vulnerable regardless of age.

Yes, and people who are slower and more fragile and take longer to heal are more so than others.

"rather hard" is really underselling things. Without considering generator->motor losses, 250W is a lot of power, even for a larger (>80kg/176lbs) rider. For basically anyone who doesn't train on the bike, this is an unsustainable effort.

Even a floor of 100W would rule out smaller/less athletic riders.

I don't think this is true, class 2 e-bikes are allowed a thumb throttle up to 20mph

Constant 250+W would force you to always travel at high speeds. That’s just not how E-Bikes operate.

Even 50W is a fairly significant boost for casual riding.

It’s got double the range of any e-bike I’ve been around. On a full charge you’ll get very uncomfortable long before you reach half capacity. I think the pedals are only to fit into a certain vehicle category and perhaps to a lesser degree for range-extension. The expectation is that you keep it charged via an outlet.

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.

>> 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.

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

you can use your phone charger with this one too

I stand corrected. I did not know that class 2 allows for throttle-only operation.

If you can't figure out what I mean, maybe don't be so confident it's dumb?

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.

It is a trope at this point. I think Rivian has done a pretty good job here, but the trope is that the non-bike companies wanting to implement their technology, also feel the need to reinvent the bicycle part of the bicycle. Ignoring the decades of learning about what value a bicycle actually provides, and treats it like a technology problem.

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.

This is a Class 3, so it needs pedals to hit 28mph. It also has a throttle up to 20mph for class 2 operation.

176lb is below the average male weight in the US by around 25lbs :(

Reading this back my wording looks a bit contradictory, so to be extra clear: "put yourself on the bike" is the part that isn't about pedaling. Pedaling comes in later.