Comment by chickensong | Hacker News Reader

Comment by chickensong | Hacker News Reader

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Cycling is special IMHO. It can be strenuous exercise like running, or a casual cruise that's even easier than walking. The speed is highly adjustable and easy to get in the sweet spot for that moment. It's not too slow to get bored, and not too fast to miss out on your environment.

Bikes are also a wonderful expression of physics, and the effect of centrifugal force is a key reason why cycling is special. The property of increasing stability with speed is amazing. Leaning not steering is also wonderful. The flow state you can achieve on a bicycle is unreal. Mind, body, and your physical environment in unison.

There's a mechanical beauty as well, that's easy to understand, but with plenty of depth to dig into and enjoy. Wheels and gear ratios are some of humanity's greatest achievements, and you get to pair that with interesting geometry and materials that have a direct impact on your experience. The difference between riding a junker that's not right for your body and a nice/fitted bike, is like the difference between wearing a burlap sack and a tailored suit.

Physical exercise is good, but bikes are much more than just a means to stay fit and produce endorphins. I wish everyone would bike more. Truly one of life's great joys.

> Bikes are also a wonderful expression of physics

And efficiency! A human on a bicycle is more efficient than any other vehicle or animal. If we ran on gasoline, a cyclist would get the equivalent of roughly 1,000 miles per gallon. A well maintained bike drivetrain can reach 98% efficiency. Compare that to an ICE car which loses up to 70% of its energy to heat and friction.

The Aerovelo Eta, used to set the human powered speed record, has an MPGe of 9544.

https://www.aerovelo.com/eta-speedbike

Where did you get this? Humans, like all mammals, are not very efficient at converting chemical energy into mechanical work, definitely less efficient than ICE at 30% COP (aerobic process gives about 20-25% COP and anaerobic is horrible 5-10).

Humans are not metabolically efficient, yes, but on a bicycle the total transport efficiency is more efficient than anything else, and 30% for an ICE car is in ideal, optimal conditions. Real world stop and go driving is likely closer to 15%.

A human on a bicycle is efficient because of mass and that the bicycle itself is a very efficient machine. A cyclist will burn around 30cal/mile of riding. If a gallon of gas has about 31.5k kcal of energy, then that's about 1,000MPGe for a human on a bike. A 200lb person + 20lb bike requires very little energy to overcome rolling resistance compared to a 2000+ lb ICE vehicle that spends the majority of its energy just to move its own mass.

I don't know what "total transport efficiency" is or how is it measured, I just noticed you mentioned 70% of energy wasted by ICE as if humans waste less than that. As for more efficient than anything else in terms of MPG, you might want to check the current MPG record, it's in range of 15K MPG on some hydrogen powered car if memory serves.

Here's a source for that. I also remembered it.

https://www.scientificamerican.com/article/a-human-on-a-bicy...

Did you read it? Humans aren’t very efficient movers—until you put us on a bicycle, when we become some of the most energy-efficient land travelers in the animal kingdom. right at the start. It talks about animals only.

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