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0 pointsexasperaited4mo ago0 comments

Motorcycles I could imagine.

Do e-bikes really need significantly more power than they have? They already run arguably dangerously fast for their application. Is efficiency not the primary target there?

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gruturo4mo ago

e-bikes don't necessarily need more power but they could benefit from a smaller and lighter motor. If it becomes small enough to "disappear" in the pedal assembly for example, it would allow more design/parts commonality with normal bikes and fit more people's aesthetic criteria.

The lower weight would be definitely welcome, my ebike is comically heavy compared to a normal one and sometimes I have to carry it up flights of stairs (some German railway overpasses, grr).

Also in scooters it could fit in the wheel (since the wheel is tiny and has to spin quite quickly - no reduction gear needed vs a bike with 26-28" rims) allowing a simpler design and cost savings. But maybe in scooters they're already using in-wheel motors, I'm a bit ignorant there.

amluto4mo ago

There are some advantages to hub motors in an e-bike, and if the motor and an appropriate gearing system could be made light enough the disadvantages would be reduced.

Oddly, a very large majority of current fully suspended e-bikes with rear cargo racks have those racks unsprung, which suggests that most e-bike manufacturers don’t actually care about the handling of anything other than their pure e-MTBs.

TJSomething4mo ago

While more power may not make sense, less weight is an easy way to get more efficiency. And if you can keep the same power at a lower weight, that's a win.

chrisweekly4mo ago

Hmm. I am NOT an expert (though I ride and have owned 3 traditional motorcycles). IIUC, reducing unsprung weight is really crucial for handling -- which is why so-called "inverted" forks / front shock absorbers became basically the standard.

kangs4mo ago

bicycle weight ratios are completely different from even motorcycles. a bike wheel can quickly become heavier than the frame for example.

maeln4mo ago

The motor to battery weight ratio on e-bike is much more than for cars. Having a lighter motor would improve the efficiency.

Someone4mo ago

They don’t need this motor, but if it can be scaled down… at over 10kW/kg sustained, one could wish/hope to get 200W at 50g (disclaimer: I have no idea how this scales with size). Combine that with 1kg of a 600Wh/kg battery (https://news.ycombinator.com/item?id=45797452. Again, I have no idea how realistic that is), and you have a bicycle that’s only a little heavier than a non-electric one, but gives you a boost for 3 hours (more if you use it sparingly. If you’re cycling at leisure, 100W already is a lot of power)

Y_Y4mo ago

For reference, an average commuter cyclist has a power output of about 200W, a world-class racer can do about 600W.

Ref: https://www.cyclinganalytics.com/blog/2018/06/how-does-your-...

state_less4mo ago

Yes, all else equal, we want lighter motors in vehicles.

I'm always interested to hear about the latest in lighter and possibly more powerful and torque-y e-bike motors.

varispeed4mo ago

If engine can be produced cheaply, can it be limited "in software"? It's like saying people shouldn't use Rasberry Pi to blink an LED.

JKCalhoun4mo ago

Yeah, you kind of shouldn't use a Raspberry Pi to blink an LED, though. Great "Hello World" project. But there are so many ways that are cheaper, lighter, smaller and more reliable (and don't require a lengthy boot-up).

fragmede4mo ago

Ah not to worry we can make it a web service and host it on the cloud and of course you wouldn't want to run without a authentication so you'd need that and also a database and what if you want to blink the led securely so you'll need to use a homorphic database which is very computationally expensive so just need a couple of VMs and anyway you should start with https://www.npmjs.com/package/blinking and go from there.

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