Riding in a peloton is the most energy efficient locomotion – research (2018)
bikebiz.com
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edit: Forgot the best part. The formation ended when someone near the front swerved to avoid a hole in the trail. Person behind them--taken by surprise--abruptly braked. Chaos ensued. Chaos propagated upstream and eventually got to me. I ran over a downed bike and flew over my own bike landing on my handle bars--broke a rib (though didn't know it until a few days later). Why would the organizers of a casual charity ride allow formation riding, you ask? They don't.
There are a couple of rules you end up learning.
1. When you're leading a peloton, never go aero (when you lower your upper body so you're "cutting the wind"). Always keep your eyes on the road ahead, looking for potholes.
2. Whenever you spot a pothole, call it. Shout "pothole", loud and clear. As you go around it, point to it for the person behind you.
3. When someone in front of you shouts "pothole" and points to it, shout "pothole" and point to it, recursively.
4. Never break abruptly in the middle of a peloton.
5. For maximum efficiency and safety, your front wheel should a wheel's distance from the rear wheel of the bike in front of you.
6. If you need to do anything that is somewhat abrupt, like leaving the peloton, always warn, loud and clear.
> When you're leading a peloton, never go aero (when you lower your upper body so you're "cutting the wind"). Always keep your eyes on the road ahead, looking for potholes.
You can do both, with flexibility and core strength. If I'm on the front in a road race, I'll be in the drops. My breakaway performance improved dramatically when I started including yoga & pilates in training regime.
However, for time-trial or triathlon bikes, i.e. those with specialist aero bars that help us become more narrow to the wind, you'll hear general advice to never get down on the aero bars in a group. That certainly is a good safety guideline to follow, with the exception of training for/racing a team time trial. Not so much due to visibility as it is the altered handling characteristics and lack of brake levers.
> For maximum efficiency and safety, your front wheel should a wheel's distance from the rear wheel of the bike in front of you.
That's a lot. In a competitive event we're often down to a few centimeters gap between wheels. In such circumstances the proper safety protocol is to be slightly laterally displaced from the wheel you're following, enough that any unanticipated change in speed means your front wheel slides past their rear wheel rather than making tyre contact. The choice of left or right generally depends on wind direction, and on very windy days this coordinates with echelon formation.
Same here, although I only won a couple of very minor races
> > When you're leading a peloton, never go aero (when you lower your upper body so you're "cutting the wind"). Always keep your eyes on the road ahead, looking for potholes.
> You can do both, with flexibility and core strength. If I'm on the front in a road race, I'll be in the drops. My breakaway performance improved dramatically when I started including yoga & pilates in training regime.
Yes, it obviously depends on the speed the group is going, but the front of the peloton will always go into a more aero position when riding fast.
> However, for time-trial or triathlon bikes, i.e. those with specialist aero bars that help us become more narrow to the wind, you'll hear general advice to never get down on the aero bars in a group. That certainly is a good safety guideline to follow, with the exception of training for/racing a team time trial. Not so much due to visibility as it is the altered handling characteristics and lack of brake levers.
I know several group rides who would not let people with tribars (typically only triathlete would try) into the group. You'd likely get pretty aggressively get told to f off (hanging of the back might be tolerated). As you point out there are pretty good reasons for it.
> > For maximum efficiency and safety, your front wheel should a wheel's distance from the rear wheel of the bike in front of you.
> That's a lot. In a competitive event we're often down to a few centimeters gap between wheels. In such circumstances the proper safety protocol is to be slightly laterally displaced from the wheel you're following, enough that any unanticipated change in speed means your front wheel slides past their rear wheel rather than making tyre contact. The choice of left or right generally depends on wind direction, and on very windy days this coordinates with echelon formation.
Again full agreement. Living a large gap in a peloton or pace line is again a pretty good way of getting a "talking to" (more or less aggressive depending on the group and the speed). One should also point out that if it came to a touch of wheels it is largely considered the fault of the person in front.
Finally and that is something many beginners get wrong. If you're riding two abreast (large group training rides will often ride like that), you should have your handlebars next to each other. Imyou can then ride very close (handlebars can touch) without danger, because if one needs to come very close you just lean into each other. The dangerous situation is when handlebars are staggered because you can slot into the bar of the other person. They then try to move away from you (shouldn't but often happens) and you both fall.
I should've given some more context. I'm from a South American country, we used to train in a road that goes around a fairly big park, so it makes a +- 3km rectangular lap. We rode on the lane closest to the sidewalk, so we could pretty ride past the traffic lights.
It's a pretty busy road during the day, but during "training hours" (19:00), there's less traffic. Still a lot of cars, and there's a bus stop along the way, and not every bus driver respects cyclists (they'll overtake you, then stop in front of you). There's a particular section where there's a major road that merges within our lap, and there's almost no working public lights, and the road is full of potholes, and there's a broken pipe somewhere, so the potholes are always full of water.
So yeah. If you're riding in a fairly big peloton, NEVER go aero. It can literally kill you. I've seen it happen.
Woke up in excruciating pain, went to hospital and nearly died.
Turned out he'd perforated his colon extremely badly, and you only find out those sorts of injuries if your digestive system starts operating, pumping your last meal into your body.
They had to remove all the muck out of his body, and then he spent a few months on fluids and losing a lot of weight.
I guess the lesson is, cycling injuries are often the type of body injuries that take some time to identify. Keep an eye out.
One of the stories he shared was that he got to a car crash, woman had been t-boned at about 30MPH but was fully alert, able to move extremities, and according to stepdad, seemed like a bumps and bruises case.
They still load her up to take her to the hospital and a few minutes into the ambulance ride her vitals spike and she’s dead within a few minutes before they make it to the ER.
Turns out a broken rib had split open one of her organs but nobody had the slightest clue until it was too late (although it didn’t seem like there was much they could have done anyways).
She continued mountain biking for a day and a half after the fall, haha.
She’s still hurting a lot. I hope I never break a rib. The worst part is apparently I won’t know when I do!
You know you've broken a rib when the pain from the injury gets worse and worse over time, rather than less and less. 3 days of pain in your rib getting progressively worse? Time to head to the hospital
Last time I went they warned me of not being able to breath deeply enough, hence I got stronger pain-killers. Something about possible infections or something like that, was a while ago.
We’re in Canada but our healthcare situation in our area is pretty bad. Sometimes weeks to get an appointment, walk in clinics are loaded by the early morning, triage in emergency rooms can totally exclude problems like my wife’s within any reasonable time frame. I think some parts of the country are okay right now (I hope) but we haven’t had a family doctor or reliable access to healthcare for years now.
Redundancy and intercostal muscle.
I am not saying that from a moral standpoint, I really like personal convenience but I don't like it so much when other people lives are made miserable to support for my personal convenience. And I'd like to think that solutions that work for the collective can be optimized to be made more convenient for everyone.
/s
It would be like an internet company trademarking Browser, or a car company called Engine.
I guess talking about browser chrome isn't what it used to be anymore.
This seems highly questionable. I would hazard a guess for example that cargo ships are significantly more energy efficient per gram per kilometer.
Edit: indeed my intuition was right, going by Wikipedia. Domestic waterborn and rail can transport a metric ton (i.e. 1000 kg) of freight 4-6 km using 1 MJ of energy. By contrast, a velomobile can transport a person ~12 km using 1 MJ of energy, but a person weights only about 70 kg.
It doesn't say it's limited to humans.
They could reach up to around half a million miles per galleon.
This made me consult a search engine and I was not displeased.
On page 10 in the pdf you can see the vehicles and animals compared.
But I guess the massive size of freighters allows them to still be more efficient than trains.
Also, riding a bicycle (even while coasting and not expending energy) is not exactly comfortable, so stacking people into a container might not be all that unreasonable a comparison.
Not subsidizing the bad and subsidizing the good would be a very low hanging fruit to start with.
You might want to consider that there is actual value in searching solutions that still allow people to maintain their mobility, while reducing the negative impact on everything.
Yeah, if it gets steep enough, walking is less effort than cycling. But downhill is essentially free for cycling and definitely not free for walking.
And of course if you introduce grass or other even thicker vegetatation, then the advantage of a pair of wheels diminishes further.
However there are competitions for non UCI bicycles. The speed world records are among them.
And before someone jumps in about how those technologies are actually somehow bad for the track or race car drivers don't benefit from them, F1 actually had to give up their 1994 ban because every team was doing it anyway and the FIA couldn't adequately police it until the ECU itself was made standard in 2008: https://racingnews365.com/traction-control-in-f1-a-short-his...
Nevertheless, there are a lot of normal people driving recumbent bikes and velomobiles already. The road I live in is part of a bike route and I can see both driving here regularly (I also happen to own a recumbent bike :) )
As the owner of a recumbent, how does it handle on dirt and gravel? Are they bitumen only?
Competitive team road cycling is, amongst other things, about the tactics of multiple riders using shared aerodynamic advantage.
If you make everyone more aero by say using recumbent bikes you diminish the advantage of teamwork.
You’d lose all the inter-team horse trading that goes on between rivals in breakaways or mountain stages. No more tight sprint train finishes.
There’d be no surprise attacks because there’d be no way to conserve energy hiding behind a rival waiting for the right moment.
Everything would be full gas all the time and could mostly be settled by looking at pure power numbers.
You’d still get a race but every stage would be a simple time trial. Effectively road racing would become a very different discipline.
Like giving all the riders ebikes. It’s still a form of racing but you lose a big part of what makes a team stage racing compelling.
I’ve always wondered though why they couldn’t allow open vehicle stages for some time trials where the riders are on their own anyway. I think that would preserve team cycling and still be fun.
Top tier cyclists in a pack do about 50km/h on the flatter stages on an upright with around 2x the power.
(Yes, I know bikers go much faster with even less protection - I'm not a fan of motorbikes either.)
But really, anything as efficient as an upright or more is fine.
If a special single-use road was required, then maybe they would have a point.
I was always curious if it was real and why not everyone does it.
[0] Example of a particularly dangerous version: https://youtu.be/p0mE2b5zu48?t=133
This isn't really as unsafe as it looks... or at least not any more dangerous than keeping their feet on the pedals at that speed.
I spent a lot of time riding around velodromes... you only forget to stop peddling once on a fixie. It is like riding a bucking horse. Perfect example:
The guy obviously has skill and experience on two wheels, you kind of picked a poor example.
I wouldn’t be at all surprised if that rigid position was really fast though.
If I put the dropper post down on my mountain bike and get low when I am on a road hill I drop like a stone. I’ve often overtaken friends on road bikes doing that.
Matej Mohorič used a dropper post to win Milan-San Remo this year.
I could see them becoming a key aero tool on road bikes in future.
Yeah, that looks insanely dangerous. I wonder how much higher the COG is in that pose. At least the example you provided looks dense and lower.
I’m guessing this would be a different sport rather than cycling evolving.
If you want mass-start races where riders can agglomerate to reduce required power, then you're probably stuck with rules that make the bikes all much more alike than they are different.
If you want bicycle innovation, you have to go to time trial or endurance events, where drafting isn't a thing and thus the equipment could be anything.
Triathlon is a good example of how small rule changes can drastically change the dynamics of a race. They relax a lot of the UCI rules such as by allowing aerobars, but as a result you can't safely allow drafting, and the bike component of the races become far more spread out than a cycling race would be with a lot less importance laying on attacking or defending a position and group strategy becomes nonexistent. Some of that is due to the fact that there's still a run to go afterwards, but I'm pretty sure the average person would find the bike component of a triathlon less interesting than a cycling race to watch.
For those who want it, as PaulDavisThe1st mentioned, we have stuff like TT races, recumbent TT races, velo, etc. There's a lot of options in cycling depending on the niche you like.
I don’t know much about recumbent bikes.
Why is this statement true?
It seems to me that hills are still tough for recumbent bikes. Are efficient flats riders (maybe sprinters?) able to make up that much time over climbers in the flats?
A recumbent bike greatly reduces wind resistance and makes it so that the person in second does 10% less work rather than 50% (numbers are made up). It's not that hills are easier, but that pulling ahead on flats would actually be viable.
Some short course triathlons do allow drafting (including the Olympics), but those events also ban extended aero bars for safety. Athletes who compete in those events specifically practice riding in a peloton and know how to hold their lines in order to prevent crashes.
Not just for speed, but recumbents are terrible at cornering and are terrible for going uphill. Half the fun in large cycling races are the mountain stages where people go slowly uphill and then really fast and technical on downhills with many corners taken at high speeds. Recumbents would be terrible for that.
It is real! It's an extremely aerodynamic position.
> and why not everyone does it.
In races, it isn't a race legal position to use. In practice, it is a very unstable position and you can't race in it so there's not much point to taking the risk. UCI is notorious for being very strict about that sort of thing (even as so far as to ban sitting on the top tube or resting your forearms on the handlebars) and they change the rules regularly to get rid of anything they feel is too risky.
Anyway, roads bikes are pretty efficient even without a peloton. On roads. I've recently built a vintage road bike and only managed to burn 350 kcal on an 1 hr, 18 km ride. Most of it was in HR zone 2, easy. Almost flat, but still. Imagine what a velomobile could do.
Yeah this rule was ostensibly designed to prevent everyone from racing in knee-high, very tight compression socks. Shortly before this rule went in place some teams had found they had a subtle aero benefit by reducing profile and were planning to race in them. However, you get hotter.
It’s dangerous as hell.
Just look up peloton crashes. Or imagine cars driving like that.
It’s one of the main reasons to join a bike club.
A good group will call out obstacles in the road and say when the are going to slow down. They’ll have set procedures to move the group round when the riders at the front get tired.
The experience of being pulled along faster than you could ride on your own is a truely joyous experience! :D
It truly is! As a kid we used to hide behind the double decker busses on our mountain bikes at the stop and accelerate with it when it got going again. We’d be riding only a few feet from the rear of the bus and it’d pull us up the big hill home so fast. The bus driver used to get really annoyed and eventually snitched to the school so we had an assembly about it !
boys are stupid!
I’d never have the balls to do that now!
Riding in a pack is a whole different experience, though. You have to be hyper-aware and -predictable in your lines, but the feeling of cruising along at over 20 MPH on a flat, aided only by your fellow cyclists, is something special.
i think they're called trains
My current vision for the system basically amounts to electrically coupling the motors of the carriages such that any attempt to accelerate / decelerate one carriage transfers energy via induced voltage which accelerates / decelerates the other carriages by exactly the right amount. It's like an electrical version of how all the cable cars are holding on to the same rope. No computer, no glitches, entirely dumb components.
In principle, railways would not be difficult to automate. But it hasn't happened at scale yet because industry regulations require that trains be manned, and railroad unions would strenuously object to any suggestion that this be changed (since it would likely put a lot of conductors out of their jobs).
For the sake of example, I'll focus on my second use case. A mainline heavy rail that branches into multiple light rail at the same service frequency. In this case, the carriages split off from an 8 car set into two car sets and coast to a stop at designated branch station (like old fashion slip carriages from the late 1800s). At those stations new drivers board to take over light-rail style operation. When the drivers complete the route they step off the train at which point the automatic reverse slip carriage system rejoins them into an 8 car train (one driver stays on to become the lead carriage). The drivers that stepped off then cross the platform to take over control of the next train to split itself.
A strange but doable logistic coreography that lets metro lines branch more without intolerable service frequency.
Personally i average 25-27kmh. With a friend or two 32-37, in a bunch 40+kmh, easy.
* It's just such a shame that a group >3 of cyclists turn into such a selfish bunch of self-entitled twats, i avoid them like the vermin they are. I average 100-350km+ a week or ride before anyone gets too upset at that uncalled-for statement :-)
Oh, and i can recommend the website intervals.icu - amazing cycling-analytic tech on display.
Doesn't seem very kind. You think because you ride a lot gives you permission to refer to people in that way?
I've also done track cycling where you leave a 30cm gap between wheels and have no brakes. That is truly unnerving.
What about uphill or uneven terrain. going downhill on bike is very efficient too. You can test this by rolling a ball down even a slight grade. Yes, in artificial conditions bikes are better.
One fifth goddammit!
In world war 2 the Japanese army used bicycles to invade Malaysia and modern Singapore and it was highly effective. It allowed them to continuously advance faster than retreating British forces on foot and vehicle. The key point being it was more viable to put thousands of troops on bicycles than to put them all on vehicles that could go through rugged terrain and jungle.
Under normal conditions, retreating armies move faster than their pursuers because the invaders are slowed down by destroyed infrastructure such as blown-up bridges or obstructed roads. But this time, Japanese soldiers on light bicycles were able to use narrow roads, hidden paths and improvised log bridges. Even when bridges were missing, soldiers waded across the rivers carrying their bicycles on their shoulders.
The bicycles also proved to be an excellent help in the transportation of equipment. While the British soldiers carried up to 18 kilograms while marching through the jungle, their Japanese enemies could carry twice as much, benefiting from the distribution of weight onto two wheels. “Even the long-legged Englishmen could not escape our bicycles”, remembered Colonel Masanobu Tsuji.
https://www.welovecycling.com/wide/2019/06/28/japanese-style...
Years after the war, Shimano Japan became the biggest maker of bicycle componentry in the world. They manufacture most of it in Malaysia.
https://www.vice.com/en/article/xgde8k/ukraine-is-using-quie...
If you want to go for full efficiency, safety or practicality be damned, a recumbent that makes you lie basically flat just above the ground and covered all over should be really efficient. For maximum insanity, lie prone.
Or, since they allowed multiple riders, you could build a contraption that allows multiple people to ride in a recumbent position inside a single cover.
See https://www.engineering.com/story/human-powered-vehicle-brea...
> Analysis of the vehicle performance showed that Eta requires less than 198 watts of pedal power at 90 km/h, which translates to a 9,544 MPGe highway fuel efficiency. According to Aerovelo, this is the highest per-passenger MPGe of any existing transportation technology at this speed.
And they didn't even ride that thing in a pack.
That said recumbents might be the most aero dynamic bikes, but lying down pedalling is less biomechanically efficient.
Even when you have something to push against?
I guess whatever the guys who are setting the human-powered vehicle speed world records are doing is probably close to the optimal trade-off.
Recumbent vs. upright is actually an over 100 year old battle, over misunderstanding each others needs and wants from a bike. Many recumbent people are still sour over UCI banning non-double diamond frames.
> Well if you go really really fast aero is the most important.
Yes, and in the context of the submitted article, aerodynamics is the only difference between riding alone vs in a peloton, isn't it?
Ha, now I wonder whether you could get better endurance performance, if you took the vehicle from https://www.engineering.com/story/human-powered-vehicle-brea... and stuck tank of pure oxygen in the chassis to hook the rider up to.
Didn't know what a "Peloton" is, but assumed it's what we call "Pedalo" [1].
Gave me quite a laugh when opening OPs link. ;-)
They could have called the company Wopat or something, and people still would have bought the things (given Covid, but still).
Waay out in front was a man on a bicycle. Add in the help of cumulative drag and sharing the load against the wind resistance, it makes sense.
I love bicycles!
We're close to having the tech necessary to make the tailgating safe. A critical mass of cooperating auto pilot software should do it.
Technically you are already there. All train and metro carriages already do this. :)
The control loop would have to reference the next vehicle in the chain, and adjust the speed to maintain a constant distance from it, as well as keep the centerlines of the two vehicles aligned. For emergency braking and other surprise situations a broadcast system would be useful.
Public transit was made into a small fraction of traffic. [0] It absolutely doesn't have to be that way. If you live in a city you are likely going somewhere that a lot of other people are going to as well.
With proper urban planning a door to door car should only really make sense in a rural environment. And that is absolutely a needed mindshift to curb GHG emissions.
I made a deliberate choice of moving to a country and city with good governance and planning. I haven't owned a car in 5 years. When I do absolutely need a car I will just rent one for a weekend trip or for hauling big things. It still is a huge saving.
The only pro-car argument I can think of is the prepper aspect of having a getaway vehicle in the event of a natural disaster.
[0] https://www.vox.com/2015/5/7/8562007/streetcar-history-demis...
I think "was made" is the key term, since that is what defines the current state of reality, which is where our solutions must exist. Any feasible solution will not requiring destroying the last 100 years of development, in the US. Improvements are still a good thing, especially if they can be implemented as a glorified, cooperative, cruise control.
I'm all for rail, since more trams could mean my 20 minute drive wouldn't have to be 3 hours by track + bus + 3 mile walk, but putting enough metal on the ground isn't trivial [1].
1. https://www.vox.com/videos/2022/7/29/23283654/california-hig...
Could you explain how this could be approached, with the wide sprawl of suburbs that exists, today?
There is nothing ground breaking or sci-fi about it. It has been done many times over in several places around the world both dense and sparse.
It just needs political will and budget. The main problem you guys have in the US is how entreched lobbyists are.
Granted, that's counting vehicle-kilometers and not person-kilometers for cars, but calling it an "extremely small fraction" is not quite accurate. ;-)
1. https://www.urban.org/urban-wire/us-public-transit-has-strug...
This isn't some new idea [1], so I'm not sure why I'm being downvoted. This has always been a goal for self driving.
1. https://www.motorauthority.com/news/1076588_sartre-self-driv...
It’s not that close granted but it does improve safety by watching the car in front on a long drive.
What are they counting as the input energy for a hang-glider?
Yes, you put energy into the throw. But if you count the guy hauling a hang-glider up a hill (or in other words it's potential energy at the top), I wouldn't think of hang-gliders as energy efficient at all. So either way I'm having trouble reconciling the comparison. Either they're infinitely efficient (zero input energy) or not comparably efficient.
Maybe they're counting the twitches / muscle movements and such of steering the apparatus while in flight?
From an individual perspective, how is it any faster than walking alone (or everyone taking the same break at once, assuming they don't take any time to regroup or string out). If it isn't more efficient from any given person's perspective (for all of the walkers), it isn't better for the group.
As for evolution, bicycles require smooth roads, which are not naturally encountered at all.
But internal combustion engines themselves are pretty maxed out on efficiency, in the mid 30% range.
At least in the US, motorcycles are more often toys than tools so people buy bikes that emphasize other characteristics at the great expense of efficiency, and the more practical and efficient options are not even for sale.
Unfortunately brand does not sustain a company in the absence of a product+price market fit
That brand is only known in few US states, the world refer to peloton as https://en.wikipedia.org/wiki/Peloton
They actually had the balls to threaten a few bloggers for using the term peloton correctly on YouTube.
Luckily the blogger didn’t give in and the exercise firm had to back down.
I also note that tickets to the (most excellent) Tour of Flanders came from a different firm also calling themselves Peloton.
So the exercise bike group aren’t exclusively trading under name either.
Just cut a potato length wise into circular “wheels” and fry them up.
Have always additionally thought the company Peloton was a bit absurd with naming
I think in this case it's simply that people don't know where the term originally comes from.
I don't see an equal or more terse way of saying the same thing.
"Planet’s most energy efficient locomotion is peloton riding, finds new research"
"New research finds peloton riding is planet’s most energy efficient locomotion"
Arguably these put the emphasis on different things, but they're pretty close.
The original (before HN edited the title) told you what the subject was immediately. It went from specific to general.
"Planet's most energy efficient ..." is the most terrestrially broad introduction one could use.
Likewise, "New research finds ..." is such a common phrase that it almost repels people (particularly since much research is bogus).
It's only a subset of US English speaking people which will be confused by the original title. To the subset of US residents who have never heard of the company Peleton, and the hundreds of millions of English speakers outside the US, this headline wouldn't have been confusing at all.
Riders form a paceline because of the crosswind which forces everyone to look for draft on the left or the right side of a rider in front of you. Eventually, there's not enough road for everyone to be in the draft and the first paceline is formed (also called an echelon).
More specifically though, paceline refers to the mechanics of the echelon, the way riders rotate, or take turns at the front to stay in the echelon. This rotation is the paceline.
Pacelines for group rides and the like can be formed whenever, and they do not form just because of a crosswind. When I used to train with a group, we would almost always form pacelines in single file, on every ride.
1630s, "a small body of soldiers acting together but separate from the main body of troops," from French peloton "platoon, group of people," literally "little ball" (15c.), hence, "agglomeration," diminutive of Old French pelote "ball" (see pellet).
Of course, you won't be doing 5-10% the output because there's still mechanical losses and rolling losses, but they should have decent models of those as well.
The riders are not exact clones of each others. The bikes aren't going to be exactly identical either. You won't be able to have them ride in an exact straight line with zero wind and zero temperature fluctuation. You won't be able to track the position of 100+ riders to within sub-centimeter precision while moving at 60km/h.
The actual power measurement is easy: they already have sensors for that. But good luck trying to get them to give you that data: it's like asking a Formula 1 team for their engine performance data!
Not to mention they don't have to hire or coordinate any cyclists.
Yah, that's not actually true. A human is around 25% efficient (counting only the actual energy in the food), while electric cars are around 60%.
And if you count the energy needed to grow the food, even gas cars are more efficient than humans. And that's even if you only count the payload and not the weight of the vehicle.
And flying birds easily are more efficient than humans on a bike because they can use wind to help them.
You're definitely still right about creatures that can simply catch sea and air currents, though.
> note that maintaining internal homeostasis in a human is not exactly "losing" energy to heat
If you bike a lot you will eat more. People tend to forget that and assuming the biking is "free" energy. I guess if it's just a causal activity then it is, but if you do it to commute you will end up eating more.
It's a lot more complicated than that. A certain baseline is eaten anyway for nutrition, and some foods have too many calories per unit of other nutrients for sedantry life. Maize for example can provide a decent chunk of your protein (with some pulses to round out the amino acids) and some other nutrients, but you need to be active for an hour or two per day to not get sick from the quantity of carbohydrates that entails. There's also a minimum activity level that is best for health that many people do not reach (so the calories between current activity and that threshold have a negative cost).
If we take wheat or oats as a fuel, the CO2e footprint is roughly the same ballpark as the mass of food (or less if they are grown in certain niche ways which are high labour or use green ammonia for fertilizer reagent and electric tractors).
100g of either will get you 15-20km at a calm pace. This is ballpark 5-15g/km or roughly on par with electric trains.
You need to fill an EV with people every trip to match the upper bound here (including embodied carbon). Including infrastructure makes the bike a winner. Electric busses might still place if full. ICEs are out of the running.
If your fuel is exclusively beef protein though then better to use the deisel truck or just go set fire to a forest or something.
The optimal is a solar charged recumbent pedelec because it uses sunlight so much more efficiently than plants do. Something with just enough motor to keep you going at 25km/h on a mild 2% incline with the same power from the rider as walking, just enough battery to last one trip (about what a laptop holds, or double that to decrease discharge % and increase durability) and just enough solar to charge while parked. You can increase speed/distance to around 40 km/h at roughly constant emissions by adding a fairing.
After that is a ferry full of people.
Then a train/regular bike.
If you need to go extremely fast/far only trains work for large quantities of people, and the ones for whom coverage is prohibitive are best with cars.
Humans on bikes can also use the wind to help them; birds fly in formations that greatly increase system efficiency (much like pelotons)