Commercially Available Bike Generators Are Not Sustainable (2011) | Hacker News Reader

Commercially Available Bike Generators Are Not Sustainable (2011)

solar.lowtechmagazine.com

49 pointsbaud14725850 comments

Needs "2011" in the title. For example the section about friction drive hasn't been true for about a decade now

Nobody would (or should, at least) be using a lead-acid battery for this in 2026, either.

Full-cycle efficiency should be higher now. And the inverter. And the generator.

Huh? Was I wrong about something here? If so, please educate me.

Not to mention they’re talking about lead-acid batteries, which have been replaced for pretty much every application, except (for now) starter motor batteries for combustion vehicles, by the various lithium batteries.

To be fair (as a joke), it's from Low Tech Magazine. Lithium batteries are too high-tech for them. They want you to power your mechanical blender, mixer, and other machines with a drive belt. Turn the drum of your washing machine with a wood fire heating the water.

Solar panels I think are too high tech for them.

I remember reading about low tech efficient cook stoves for poor countries and thinking the misses would rather have an induction burner, microwave, and an ice chest running off a solar panel.

The server the article is being hosted on is battery powered via solar. You can see it's charge percent on any page the server sends back to you.

https://solar.lowtechmagazine.com/power/

> the misses would rather have an induction burner, microwave, and an ice chest running off a solar panel.

Those would definitely be hits.

Also, solar panels are old. Bell Labs demonstrated the first practical silicon solar cell in 1954. At some point, you're just trying to split (possibly nonexistent) hairs for an aesthetic, as opposed to making a principled stand against technology.

https://www.aps.org/apsnews/2009/04/bell-labs-silicon-solar-...

I would too...but an off-grid solar and battery setup sufficient to run the induction stove and microwave is still well into four figures - cheap for a developed country resident who wants some basic comforts in their wilderness lodge, but still well out of reach for a subsistence farmer in the poorest parts of the world.

Increasingly becoming more affordable. Especially as financing becomes easier. And you don't have to buy everything all at once.

That's the thing, like the used to be very expensive swing compressor ice chests that you can buy in the US for $150. You'd only need a 100 amp hour battery and a 100W solar panel to power it.

And you can probably share it between a few families, or even use it to run a small business.

even EVs still have lead acid batteries, not all, but most

"have" is doing most of the work here. Most EVs have a small 12v battery to power 12v components. But the driving the car to the store part is done with lithium.

Might have changed their attitude since then as they posted in 2022 about a DIY guide on making a bike generator: https://solar.lowtechmagazine.com/2022/03/how-to-build-a-pra...

I thought he was posting about some retro product until I saw the USB ports in the energy delivery. Weird that he edited his photos to look like that, and used retro components otherwise.

The author does all sorts of odd-looking optimizations in order to make the web page run on a single host of cheap battery/solar powered compute.

It does seem a bit extreme, but the proof of the pudding is in the eating: this website has been featured on the HN front page many times and I’ve not seen it ever falter. The same cannot be said for the many run of the mill “infinite scalability” cloud based SPA’s that make the front page – even those maintained by sizable organizations with hefty cloud budgets.

It is an experiment, over the years various people have contributed “odd-looking” optimisations, its a great project!

More info:

https://solar.lowtechmagazine.com/about/the-solar-website/#h...

https://github.com/lowtechmag/solar/wiki/Solar-Web-Design

https://homebrewserver.club/low-tech-website-howto.html

IMO the only optimization they 'missed' is to pre-compress the static files and images on disk, since it's cheaper to decompress on-the-fly if the client doesn't support gzip. The could use zopfli to "extra compress" the most frequently accessed files, and use this as a solar dump load to usefully burn extra power when the batteries are full (perhaps compressing with gzip -1 when Pelican re-builds the static site, or even avoid pre-compression altogether during the build process.

https://blog.llandsmeer.com/tech/2019/08/29/precompression.h...

https://github.com/google/zopfli

https://github.com/kurtmckee/pelican-precompress

I think the photos look like that to achieve a very small file size. The whole site is hosted and a small solar and battery powered server, so every MB matters.

For photographic images, dithered PNGs have worse quality:size ratio than JPEGs. If you want small files and are willing to sacrifice quality you can turn the JPEG compression up or reduce the resolution.

Yeah, looks like you are correct. It seems it was maybe as much about style/design as it was compression:

https://solar.lowtechmagazine.com/2023/06/rebuilding-a-solar...

https://solar.lowtechmagazine.com/about/the-solar-website/ (Lots of comments at the bottom about image compression)

> Our dashboard also includes a 220V circuit. That makes it compatible with grid-powered devices (110V in the US, 240V in the UK).

Retro-look nit: all are outdated nominal voltages. The US is 120 V (since the 1960s), while the UK and EU are 230 V (since the mid-1990s).

If we are picking nits, almost every panel in the US and Canada is _both_ 120v and 240v. But even electricians here commonly say "two-twenty" instead of "two-forty."

This arguably had some relevance in 2011. In 2026, cheap solar and batteries make human-powered static devices that would benefit from the extra power of a stationary cyclist completely redundant.

Some things I would like to see are pedal controlled devices. Something like a pedal controlled wheelchair, not powered by the pedals just control the forward and back motion. My mother with sever arthritis can still pedal but has a very hard time walking. It would be a little exercise doing something that needs to be done (getting around). A pedal controlled remote control lawnmower would be nifty also.

Where I used to live an elderly gent rode a very low to ground bike. Looked a lot like the silly motorbikes some peeps do. I imagine they’re out there for sale.

A recumbent bicycle perhaps? Often has pedals ahead of the front wheel, where you lay down in a hammock or moulded seat?

Yes, there are electric recumbent trikes out there, such as the Tadpole. A friend of mine got one after he recovered from a stroke and could no longer balance on a conventional bike. He rode it to work. It got him outdoors, with "anything is better than nothing" level of exercise.

That's it!

Sorry I lacked the proper name, but yes they are about. And definitely look like they could help people certain health issues. Although getting down into it would be something to consider for older peeps.

many ebikes work this way, pedaling and the chain more or less signal the motor rather than provide meaningful power... though afaik none of them do backwards for obvious reasons

she might enjoy an etrike, though more for recreation than normal day to day

Have you seen what people are doing with hoverboards + wheelchairs? Carer- & user-operated variations. Not professional solutions, but certainly fill a need.

This seems close to what you're describing: https://www.icetrikes.co/products/pers-chainless-e-assist-sy...

I'm suprised that the author didn't consider dynohubs which were also a thing in back in 2011, and are getting slightly better all the time.

> dynohub

Thanks, I learned something. I’m suprised how little drag they seem to add.

https://www.cyclingabout.com/dynamo-hub-power-drag-testing-s...

Are there options that don't limit the output power? Typically the light power is limited, so dynamos only provide around 5 W or so, which already makes them not so attractive even for charging your phone on a bike.

I think the problem with having a higher wattage is that you can't have a substantial amount without introducing what would generally be an undesirable amount of drag. It would certainly be useful to be able to engage / disengage a dynamo hub at a higher wattage though.

I'm not totally sure about the specifics since despite being an engineer, I cannot distinguish electricity from witchcraft. That said, I do know that if you want to charge your phone from your dynohub you need to ideally have some sort of powerbank in the middle.

You could attach pedals directly to motor axle and control charging power drawn precisely to ensure smooth rotation in absence of the flywheel. It could be really small.

No, you can't. Most generators have to be spun at a thousand or several thousand RPMs to put out any sort of amount of power.

Your average inexperienced person can pedal at maybe 80rpm comfortably, but probably considers even that to be "fast."

A road cyclist with a year or so under their belt will do 100rpm if they put their mind to it and are positioned well biomechanically. Above that, to do it and be smooth and efficient, especially for any sort of sustained effort, you have to have a decent amount of experience/training.

That's well over 10x too slow.

And there's still the issue of your average person only being able to put out 100-200W past about 1-3 minutes.

You can have a motor with planetary gearbox built in.

> An energy loss of 42 to 67.5 percent of naturally means that it takes 42 to 67.5 percent more effort or time to power a device (say, a blender) via electricity compared to powering the same device mechanically.

Nope. If input is 100W, loss is 60%, and resulting in output of 40W, then to increase output to 100W you don't need 60% more input (which would output 64W) you need 150% more input.

Tried one at a demo; you put in a ton of work for minimal wattage. Much better off with a decent power bank, honestly.

So Black Mirror lied to me ?!

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