I can only respond to your words. If you don't like my choice of bulb, then do your own math and show it like I did. See what watt bulb (not bulbs plural, or moving the goalposts even further, an entire bathroom) it takes for your assertion to be true. Actually I'll just do that myself because it's easy.

Now, we already discussed generating 1800Wh per month using this bike. So:

1800 / (8 * 2) = 112.5

Or in other words:

112.5W * 8h * 2 = 1800Wh

So you'd need to run a 112.5W light bulb for 8 hours per night, twice per month, just to equal the amount of electricity produced by the article author. Although you said that leaving the light on wasted more, so, let's just go with a 113W bulb. I'm old enough to remember 100W incandescent light bulbs, but even then, they were rarely bought and used because that's an insane amount of electricity for indoor lighting.

Now where I live I can't even buy incandescent bulbs because they're not for sale. For 112.5W to be average, there would need to be millions of Americans using stadium lighting just to take a shit.

I think you should take a step back and reflect on why you're so quick to attack someone for doing a cool hack (this is Hacker News) that reduces their electrical usage (in the time of climate change).

Here's a neat video of an olympic cycle sprinter powering a toaster: https://www.youtube.com/watch?v=S4O5voOCqAQ

1800 watt-hours, or 1.8 kilowatt-hours, is 20 cents worth of electricity. Using a cycle to power things makes for a neat demo, and might be good for educating people about electricity and suchlike, but anyone who expects to notice it on their energy bill or carbon footprint, or even for the installation to pay for itself, is off by a few orders of magnitude.

Yeah, the thing is, the by far best use for "bike power" is actual transportation. 0.15kWh of pedaling power can get you surprisingly far (one hour of moderate effort cycling), but would be rather unimpressive for the usual electrical applications. Apparently, almost two centuries of doing that have lead us to some very clever and pragmatic efficiency tweaks, probably because the effort-motion feedback loop is so extremely compelling to the human mind (evolution has made us brains on an endurance locomotion machine, everything else is rather unimpressive compared to peer mammals).

Not to mention bicycles are designed for converting rotary motion into, well still rotary motion, but forwards travel; not electrical potential.

I haven't done any research or taken measurements, but particularly the low-end style tyre-on-roller that I have must be awfully inefficient.

It's been briefly popular (to some extent) a couple of times to power a light while cycling. These things don't typically have large capacitors or batteries to store surplus charge, because powering the light is about all you can do! (Ok not totally fair since you're also cycling, but still.)

Many (most?) bathrooms in the US have more than a single, lonely bulb.

The author of the article is using the bike as a back up to his solar panels when the power is out. He isn't going to be running AC and arc welders off the power generated from his bike. More likely some lights and phone/laptop charging.

The power from the bike is likely to be more than sufficient for those use cases.

I really think room lights are approaching 5W/bulb. I have a 3x5w bulb setup and keep 2 unscrewed just because it’s too bright when I have to go in at night.

Incandescents are a hard sell when LED bulbs are $1-$2 and pretty reliable.