Comment by Empact
5 days ago
This, or a miniaturized version thereof could change the game for light electric vehicles - imagine an electric motorcycle that weighs substantially more like an electric bicycle.
Right now it takes about 10-15lbs of motor to produce a 3KW motor for an electric bike, this motor is about 10 times that in power density afaict.
The Livewire electric motorcycles use something like 100-200 lbs of motor to produce 1/4 as much power, 75kw, so that’s an improvement of 8-16x.
Does this motor design scale down? It's not clear from the article - the article focuses more on the relative efficiency gains over the previous model.
A 30lb 1000hp motor doesn't necessarily mean that they can also produce a 3lb, 100hp motor. It would be cool if it did, but I doubt that it does because usually component strength doesn't scale linearly.
That being said, these are still valuable for traditional EVs. Even if they are only a modest weight savings in the grand scheme of modern vehicle weight, their ability to improve packaging options will be a boon. One thing the industry has dicovered is that the generic "skateboard" platform doesn't make for the best vehicles, in terms of packaging.
I'm more fascinated by the question of whether it scales up... imagine much smaller and more efficient electric engines for cruise liners and cargo ships.
On a cargo ship the last thing you worry about is weight. To the point that they add ballast.
The article and the press release it was derived from says nothing about "more efficient", just smaller.
https://yasa.com/news/yasa-smashes-own-unofficial-power-dens...
Your average cruiseship already has an electric engine, they just have massive generators onboard to power it.
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Electric pedal bikes are already at the limit of what their chassis’s support even with small motors.
10kw+ is comparable to starter gasoline motorcycles in the US (or midsize motorcycles elsewhere) capable of going on the highway. At that point, you need to start scaling everything, like brakes, tires, and the size of the chassis.
The livewire has a motor large enough to drive a car.
The problem for electric motorcycles is the battery weight.
That can be offset by not requiring the same sort of range that's typically assumed to be required.
While I'll be likely be riding my ICE bikes for decades because one of the things I do on them is trips with 1000 or 1500km days, truth is the vast majority of my riding is sub 25km round trips from my place. Most of my friends places, a lot of the places I shop or socialise, and the office (which I pretty much never go to any more) fit inside that range. And most of those trips take place on roads with a 60kmh or slower speed limit. _Maybe_ a few short sections of 80kmh.
For all of those short trips, I probably don't even need 2kWHr worth of battery, maybe only 1. The electric motorcycles available around here seem to start at 7 or 8kWHr, and go up to over 20.
The downside to that is the smaller the battery capacity, the smaller the short term peak power it can deliver. The sort of cell chemistry and construction typical in those sort of bikes seem to be limited to 10 or 15C peak discharge, so while their 8kWHr battery can peak at 80kW or just over 100hp, if they downsized the same pack to 1kWHr it'd probably only deliver 10kW peak power.
On the other had, alternative cell chemistry and construction can look way better. I have a few LiPo drone battery packs rated at 60C continuous and 120C peak. A 2kWHr pack of those would give me 120kW continuous and 240kW peaks. Quite likely though at the expense of much greater risks of catastrophic fire. I've had a few of those pack catch fire while charging and one that self combusted in an almost explosion like fashion when I slammed the drone into a concrete pole at about 120kmh. I can totally see why an electric motorcycle manufacturer with warranties and safety reputation and legal/regulatory obligations wouldn't want to accept that risk.
I'd love an electric motorcycle that's "fun" enough to ride, and gets 25km or so reliable range. But it'd need to be at least a bit price and "fun" competitive with my little bikes, a 117kg 125cc ~25kW two stroke and a 138kg 250cc 24kW fourstroke. I have no doubt it'd be possible, perhaps even easy to build an electric bike with the same "fun" power to weight ratio, but right now not down to the sort of price that'd make me take on a project like that.
25km range is department-store electric scooter territory. A motorcycle that can do highway speeds could expend that entire range in 15 minutes or less, which would be quite a high discharge rate and also an unusual user experience for most.
Maybe what you want is a large electric bike like a Surron or similar?
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> That can be offset by not requiring the same sort of range that's typically assumed to be required.
It really can't be offset by that (with current tech). All existing electric motorcycles are both overweight and very limited on range.
Indeed, more so because that weight tends to be further off the ground than in a car.
Well, and the fun ones are power-to-weight monsters. Making them 100 lb heavier (and neutering range) is a recipe for a less exciting motorcycle. Might work for something like a Gold Wing (though limited range would also be a problem there).
Ten years ago it was a problem.
Good, even some great, stuff out there, today.
It's still a problem today, 2025. I think the LiveWire S2 models come closest, but they still have anemic range. (And we're ignoring cost, which is also much higher.)
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> This, or a miniaturized version thereof could change the game for light electric vehicles - imagine an electric motorcycle that weighs substantially more like an electric bicycle.
Sounds terrible for every other user of paths currently.
There’s no area in the world that allows e-bikes with more than 750w motors. A 3kw motor is illegal (cf Surron), unless you are talking about an e-moped requiring registration.
They are not allowed, but still commonly owned and used.
The law needs to catch up. There are clearly good reasons for people to want extremely powerful e-bikes and they should be allowed to. They can't be treated like bicycles because they're too fast but aren't nearly as dangerous as motorcycles. We need a new category for light motorcycles.
The real problem, IMO, is that the law is generally not deferential enough to cyclists and already forces them off sidewalks, onto the street, and to follow traffic laws designed for cars. There's not much else to take away, and the rules right now are unreasonable enough that cyclists always break them.
I think what I would like to see are explicit requirements for insurance and licensing for powerful e-bikes, but made significantly cheaper so that people will actually bother. Requiring helmets for the insurance would also make it much more straightforward. We can require them to take the street or a dedicated bike lane and fully mandate that they have to be walked on sidewalks.
> The law needs to catch up. There are clearly good reasons for people to want extremely powerful e-bikes and they should be allowed to.
I'm not so sure about that.
I don't want a 6000kw Sur Ron riding in the bike lane with me. The whole point of the bike lane was to make a safe space for riding a bicycle. I want the bike lanes to be safe enough for children to ride their bikes in, and having something that powerful in it is not conducive to that goal. They are by and large too fast and too unlike a bicycle for bike lanes. Having things that powerful there is going to dissuade a lot of potential (non electric) cyclists. My girlfriend already gets too freaked out by how fast some of the legal e-bikes in the bike lane go.
Certainly they shouldn't be on the sidewalk. But what does that leave? Just the road. If that's the case they probably need to just adhere to whatever standards the state has for scooters or mopeds. Which probably means some kind of license, maybe registration, and possibly insurance.
But that type of e-bike manufacturer doesn't want to make a light electric scooter that's road legal, they want to make a thing that skirts regulations by being "for off road use only".
And the buyers by and large don't want to deal with license and registration, and certainly not insurance.
Just because people are doing an illegal thing a lot doesn't mean that the law needs to find a way to make it legal.
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> but aren't nearly as dangerous as motorcycles.
What a ridiculous statement.
I don't think there's any inherrent difference, but until the laws catch up the "powerful e-bikes" are clearly more dangerous. Riding a traditional motorcycle requires a license, passing a driving test, and following the rules of the road - none of which are true for e-bikes.
But I'd love to hear why you think the opposite.
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> There are clearly good reasons for people to want extremely powerful e-bikes and they should be allowed to.
They are called motorcycles. At > 4kw they are that (here). So either you get them registered a such, get a license and insure them, or downgrade them to under 4kw, get a license and insure them as a moped, or downgrade them to 2kw and pedal assist only and register them as a pedelec. All other options is 250w continuous (you can get away with about 500w peak) and pedal assist only.
You are also not insured if you drive an illegal bike on the road.
> The real problem, IMO, is that the law is generally not deferential enough to cyclists and already forces them off sidewalks, onto the street, and to follow traffic laws designed for cars.
If we’re talking about high powered e-bikes, I don’t want them on the sidewalk either. Once they exceed the current regulations they’re in the moped/motorcycle category.
> There's not much else to take away, and the rules right now are unreasonable enough that cyclists always break them.
So what’s your suggestion? Let people ride electric motorcycles on sidewalks? Change the laws so that high powered e-bikes don’t have to follow the rules of the road?
I don’t think the current laws are unreasonable. I live in a place where people routinely ride their e-bikes on the sidewalks and it’s absolutely awful, especially with young children. Every time we go somewhere I have to hold their hands and yank them off the sidewalk at least once to dodge another e-bike zooming past. I can only hope enforcement catches up and starts impounding bikes from people breaking the law and issuing large fines, because I don’t know how else to stop this.
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Any ebike that goes faster than 25kmph in Europe and whatever it is in NA should not be allowed anywhere were pedestrians can go.
The real solution people don't want to accept is that ALL non arterial roads in ANY urban/suburban/rural environment should be limited to 30kpmh (and equivalent in NA). And by limited I mean traffic calmed: 1 lane per direction, narrow lanes, raised street crossing, raised intersections, European style roundabouts, the works (Dutch style) - so that people actually respect the speed limit because they don't want to bang their car.
Once that happens, bike stay in bike lanes (or multi use paths with pedestrians) and everything else can go on the regular non arterial roads and stuff that's registered (mopeds and up) and go on any road.
But my "solution" requires major political adoption and probably decades of sustained vision in investment. In places with good governance it will happen naturally and everywhere else will slowly be left behind.
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> They can't be treated like bicycles because they're too fast but aren't nearly as dangerous as motorcycles.
Why would an extremely powerful ebike be any less dangerous than extremely powerful gas motorcycle?
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>They can't be treated like bicycles because they're too fast but aren't nearly as dangerous as motorcycles.
As a former rider, why? Cars were the most dangerous part, in my experience.
Something that stuck with me from my motorcycle safety course, the speed at which hitting a wall is 50% fatal is 30 mph. Doesn't take highway speeds.
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> aren't nearly as dangerous as motorcycles.
Opinions differ. I have seen far more accidents with powerful e-bikes than I have seen with motorcycles, and yet there are many more motorcycles.
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In many states there’s a carve out for mopeds, for example which have less than 50 ccs of displacement. In Texas you can ride them with just a regular drivers license, but ccs have no meaning in the electric world. Should be straightforward to make the case for equivalent regulation, but would require a new advocacy campaign/org.
There is a big issue in the US currently with people buying electric motorcycles that look like e-bikes.
What is the issue? I've seen people on those bikes and they look fun to ride.
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Okay, but is it difficult to extrapolate the weight saving benefits of a "legal" power e-bike motor?
He said motorcycle. That's a market of hundreds of millions to one billion customers.
Oh nooo i have to put a sticker on it, and only allow my control to go to some arbitrary value when the cops are watching
Listen, your world may not allow you to sell an e-bike with a 1000hp motor on it. But my world allows me to put a 1000hp motor on an e-bike and not tell anyone.
Now hold my beer...
There's a difference.
I've noticed that people seem to believe as long as they bought something it should be safe. If you're smart enough to build something, I have to hope you're at least smart enough to realize that there might be consequences.
Take your beer back, I'm going for a rip next.
So that you can flip over in an uncontrolled wheelie at an even lower fraction of the throttle? Even if there was infinite energy throughput (aka power) at zero mass, the main limiter for power per total system mass would still be the battery. In any practical setup, even in super short runtime designs, getting, say, twice the power would not all that dramatic a runtime hit if it was achieved by scaling the same motor technology and paying for the extra mass with a little battery capacity. Unless of course you want to actually use that power increase for any meaningful fraction of the runtime, then you'll obviously drain the battery fast. But a zero-mass power increase would not change that a lot either.
Increasing power density (of the motor) just isn't worth much when it does not happen to coincide with an increase in efficiency (and then the battery mass saved for achieving the same range will quite literally outweigh the mass saved by a smaller engine for achieving the same power)
The good news is that those striving for power density aren't really at liberty to completely ignore efficiency in the process because cooling is a key issue for them.
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