Comment by kowbell
7 hours ago
My partner just got a rowing machine that offered "watts" as a unit of how hard you're going (like "calories" or "mph") and got me wondering if they made rowing machines that could slowly charge a battery, and how much I'd need to row to power one of them fancy newfangled M5 Max MacBooks answering prompts.
All that to say, CrankGPT, I am your target demographic and if you don't respond to my request for a demo I'll be cranking my keyboard with bad reviews online. Or cranking a rowing machine that powers an LLM to do it for me. Wait...
For reference, this is what 700W cycling looks like: https://www.youtube.com/watch?v=S4O5voOCqAQ
I took several biomechanics classes as electives back in my undergrad, and in one assignment I remember comparing the energy outputs between the human and robot equivalents of different tasks, whether or not the robot was humanoid in how it was designed. The most impressive think that stuck with me is that humans are incredibly efficient, from an energy perspective, in anything we do, compared to machines. Every time we delegate a task to a machine, we are using several orders of magnitude of energy to do the same thing. For most tasks, it feels wrong, but it doesn't make me any more willing to give up my car. Maybe if I lived outside the US.
> The most impressive think that stuck with me is that humans are incredibly efficient, from an energy perspective, in anything we do, compared to machines.
Humans are efficient, but not across the board. Trivial counterexample: walking is incredibly energy inefficient vs a bicycle or other wheeled conveyances whose primary dissipater is rolling resistance.
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"Every time we delegate a task to a machine, we are using several orders of magnitude of energy to do the same thing."
Might this just be selection bias? I mean, if humans can't do a task efficiently, we're not going to do the comparison with a machine.
Some actions we do seem (to me) very inefficient when compared with machines. For example: grating carrots and brushing teeth.
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If you live in most places in the US other than the urban heart of a few very large cities you have to take a huge hit to your ability to get places in a reasonable time frame without a car. I have hope some more cities other than NYC are improving the situation, but as it is the closest I got to using public transit for a commute was when I was going to one of our other offices in a different downtown area I would drive my car to the park n ride to take the train the rest of the way. The train saves time and sanity because traffic downtown is a nightmare, but that drive takes 5 minutes, and it would add 20+ minutes if I had to walk to the closest bus stop so I could take the bus up to the train station.
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> humans are incredibly efficient
Humans cannot fly.
If you're comparing raw calories to output, yes. Even gasoline has a caloric value, but humans can't drink gasoline. Growing and preparing food for human consumption uses a lot more energy than pumping and refining gasoline, so at the end of the day, human efficiency gains are not that impressive.
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Unfortunately, humans want houses and cars and vacations and such, which makes them very expensive. ;)
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For more reference how insane 700W is, the average FTP of a world tour pro road cyclist (i.e., Tour de France) is ~350-420W/6-7W/kg. FTP (Functional Threshold Power) being the avg you can sustain for an hour without fatiguing.
My own is ~250W @ 3.12W/kg. I can't even hit 700W yet, let alone for over a minute. My 5 second power is ~640W.
Crazy numbers.
Can you still touch your toes? I doubt Robert could... hopefully your own practice leaves you more balanced.
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A trained powerlifter probably exerts a few kW on a heavy lift, but only for a second or two.
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I am a nerdy blue collar electrician and that was incredibly interesting. Only 0.002kWH from that beast of a cyclist.
I would suspect my equivalency to be about 1/3rd a Robert [unit of measure from vidlink].
I'm sure he could have generated way more total energy if he wasn't trying to get get that max power.
1hp/750W or so sustained is insane power for all but a few and that is still for relatively short time periods.
1HP sustained is not insane for a horse. A human OTOH is a very different matter.
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When I was 11 or 12 I powered an incandescent bulb with an exercise bicycle. I think it was 40 or 60 watts. I can totally understand why that guy was exhausted: 60 watts wasn't hard for me, because I used to ride uphill every day after school, but the other kids could only get a dim glow.
I can do 300W for 30mins - does that mean I can barely heat up a Pop-Tart?
Spend 30 minutes charging a battery and you should have enough energy to turn any flavour of pop-tart into carbon flavour.
Even without a battery, I could easily imagine designing an efficient single slice toaster that could handily brown a pop tart on a 300W budget.
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That actually could toast a few batches of Pop-Tarts.
If you like then "golden," perhaps the entire box.
... at 1:03 he hits steady 700W. At 1:29 shows they kept increasing the incline at least to 40 degrees. Why not keep it at the same incline? . . .
It was hard to see from the video, but I suspect the machine he was on increases resistance as pedal speed decreases to try and keep him at a constant output.
That's a pretty common device for elite fitness testing.
It’s basically well known to cyclists that training with a power meter that tells you “watts” more accurately gauges effort and caloric expenditure. (Heart rate gauges subjective effort however, taking into account stress, caffeine intake, etc.)
It’s also interesting that the industry has settled on using watts to mean rate of useful work whereas calories to mean the total work including inefficiencies, despite that calories is just a unit of energy. A rule of thumb for cyclists is that in addition to usual unit conversions, the “calories” figure should be multiplied by four to account for energy expended by the body but not used for rotating the pedals. I don’t use rowing machines but I’m sure they would have a similar conversion factor in order to calculate calories.
You can get a dynamo hub front wheel for push bikes: https://bikepacking.com/plan/dynamo-hubs-lighting-charging-g...
However you can expect around only 3 watts of output at normal speeds and you will need to put in around 5-7 watts of power for the same speed. This is barely enough to trickle charge modern phones.
Annoying. Blame the Germans and their lighting laws for bicycles. I want human powered USB-C with enough oomph to power a modest sound system or lights, whilst charging my phone. The allure of USB-C is what interests me, but 3W is not much to work with. Also annoying, no rear dynamo for my bike, so I can't even double up to 6W.
I will probably end up with no sound system and just expensive dynamo lights, using a USB speaker that doubles up as a power brick.
There is a nice USB battery kit for dynamo that fits in the steerer, so it is soldering iron time for that, so might as well learn how to do USB-C power things.
One day there will be structural solar panel batteries that can be 3D printed into lightweight bicycle frames, so maybe I will stick to throwaway lights until then!
> power a modest sound system
please don't inflict your music on everyone around you.
Some of the bottle style ones claim to go up to 6W, they would also be easier to double or triple up. They are not nearly as nice and efficient as the hub dynamos though
The "Low Tech Magazine" has a guide to building a DIY bike generator https://solar.lowtechmagazine.com/2022/03/how-to-build-a-pra...
Unfortunately even with the bike it seems like you really need to find one machine that can be repurposed, a rowing machine seems a bit of a stretch.
> got me wondering if they made rowing machines that could slowly charge a battery
The Concept2 rowing machines can power itself using the power you generate by rowing, so we're partly there.
> offered "watts" as a unit of how hard you're going (like "calories" or "mph")
It's the only unit that makes sense tbh
Soon enough we will see rowing machines rated in max TFLOPS.
We already get TFLOP per watt so you can compute how much flops you are doing while cycling
A fairly untrained cyclist is usually able to maintain 200W, so yes this is definitely possible
An untrained cyclist is not able to maintain 200 watts.
For an average untrained male cyclist who is 175lb, they should be able to maintain 1.5-2 w/kg over an hour, or 120-160watts. A beginner cyclist who's been cycling recreationally over over a year should be able to attain 2-2.5w/kg which is 160-200 watts. A recreational cyclist who's be training for several years should be able to maintain 200 watts.
Trust me, I'm a cyclist, and I cycle with a power meter.
As an average male who is ~175lbs and untrained at cycling, this is hugely validating for my terrible idea; 140 watts is the max charging speed for 16" M5 MacBooks. I can finally stop thinking for myself and have my computer do it all for me, powered by my big beefy legs.
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Just one more follow up and I'll be done, promise. The average power output (FTP) of someone on zwift, a indoor cycling game, is a whooping 185 watts.
I just rode with an untrained cyclist (new to cycling) yesterday. The person averaged 80W over five hours. It’s about right for an actual untrained cyclist.
My best is 980W - for 1 second
That's solid. If my memory is correct, and my teachers were correct (both of these are suspect) back in high school, a human should be able to momentarily exert about 1 horsepower at maximum effort. We did an experiment on how much power we could output at maximum effort. We tested it by sprinting up some number of flights of stairs, and timing it. As I recall we did conclude that in round numbers the hypothesis was correct.
But that was 35 years ago and it was a high school physics experiment meant to be entertaining more than precise.
And a good sprinter can make some toast!
I'm still sour they had only one toast in, in a two slot toaster
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Isn’t that a black mirror episode? Anyways, much like the Matrix, using humans for energy is insanely inefficient.
At low effort (i.e. active recovery can-do-this-all-day-every-day) levels, it's quite efficient. That assumes that you're fine with whatever let's say ~120w continuous can get you, which is what the m5 max 16'' mbp peaks at (in my case) during inference (ds4-flash)... so I guess it's quite usable, actually :)
Imagine the work(out)station of the future.
</s> (or not)
Yes, Fifteen million merits, one of my favorite episodes.
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