Is there a list of "kill switches encoded in law autos can't make" somewhere?
I know the vehicle data recorder, and I've heard that LTE radios have to report occupancy, though I can't find a requirement that cars need an LTE radio.
I was hoping somebody would chime in on the sustainability of helium for airships.
I'm a total amateur here.
Is there no hope of finding a new source of helium?
Is there any opportunity for airship gasses that are reasonably competitive to helium but have a much more abundant supply? Is helium the only possible such gas (besides hydrogen)? Are competing gases 30% less efficient or 3,000% less?
> Is there no hope of finding a new source of helium?
Not on Earth, or anywhere in the Solar System except the interior of the Sun, as far as I know. Mining the Sun's core for helium is unlikely to be practical any time soon. :-)
> Is there any opportunity for airship gasses that are reasonably competitive to helium but have a much more abundant supply?
No. The problem is weight. More specifically, the weight of the airship in total including the gas inside, compared to the weight of an equal volume of air. So obviously any gas that is as heavy as or heavier than air won't do. And that only leaves, by my count, three possible gases that aren't already in air, that are lighter than air at all. The comparative weights are, roughly speaking:
Hydrogen: 2
Helium: 4
Neon: 20
Air: 29
So the maximum amount of weight available for all the rest of the airship--its structure, engines, passengers, cargo, etc.--would be, roughly speaking:
Hydrogen: 27/29
Helium: 25/29
Neon: 9/29
The hydrogen case is known to be easily doable, but of course it also has the huge downside of flammability.
The helium case is doable, but not easily: once you've done the structure and engines, the weight left over for any kind of payload, i.e., passengers and/or cargo, is not very much.
The neon case is simply not practical: there isn't even enough weight left over for a reasonable structure, let alone engines and payload.
Hm, interesting. Helium-3 would be better than Helium-4 (which is what I assumed in the numbers I gave), its weight is halfway between Helium-4 and Hydrogen gas.
Fusion and fission breeders are expected to create helium to some degree. No idea if it’s even worth mentioning here, but basically we’ll get more by atom manipulation and that’s it.
It's completely possible to build an EV that isn't connected. The idea that electric power means networked spying is an invented fiction. Due to the privacy-conscious background of one automaker, a vote by the board mandated that all their cars be able to function in a completely disconnected, non-reporting mode:
It is also Porsche, a company that prides itself on long-term support. Just look at the iconic Porsche tractor commercial. They want their car to work as well tomorrow as it does today. They know that communication standards change. Every "connected" car will, in a decade or two, be a disconnected/bricked car.
I really like how they're rolling out updated headunits for all their cars right now. Just about every Porsche from the 1960s to late-2000s can be updated to support a modern Porsche infotainment interface as well as CarPlay/Android Auto.
Porsche will sell you a new dashboard for your classic 911 that appears visually identical to the original, but is entirely modern in its construction.
Porsche's classic division is really setting the standards for supporting older cars. They realize over time it'll become an increasingly relevant portion of their business and just increase revenue. You can even send a car out to Germany and they'll fully restore it (at quite a price). The big thing though is they simply produce parts for their older cars.
Mercedes-Benz is also pretty up there for supporting their classic cars. Aston Martin also increasingly building out their support for their cars. Ferrari and Lamborghini starting to get more into the game, but for those brands it very much remains going to a big few shows in the EU to round up parts at times. Toyota, Nissan, Ford, Chevrolet also have some levels of support.
I worked at the grand opening of the new classic restoration center next to the ATL airport and saw for myself how committed Porsche is to keeping their entire lineage of vehicles on the road. IIRC they said ~75% of all Porsche vehicles ever made are still registered.
Really have to thank the 3d printing revolution for a lot of these classic parts support. They no longer have to keep a large supply of all sorts of old parts around in storage, they can just redesign them in a way that can be 3d printed and manufacture them on demand.
3d printing isn't as useful as people think, not for old cars. The parts that wear out are the parts that are put under some sort of load. You cannot 3d print a shock absorber. You cannot 3d print a connecting rod or bearing. Sure, you can print out a plastic widget for holding a mirror in place, but you cannot print out the actual mirror when it breaks.
Porsche is already thinking of 3d printing piston heads since their research is showing it's stronger than if they forged it.
I don't think there'll ever be a need to 3d print shock absorbers or bearings, since those tend to be commodity wear parts and there will probably always be compatible modern variants (or if you look at some parts guides, many current cars still use the exact same basic parts from several decades ago).
Engine blocks and major large internals like conrods or more commonly needed transmission internals are the parts I think will be most difficult to keep stocked.
I've got a Nissan LEAF from 2012, and it had a handful of useful features that have disappeared with the loss of the cell network (the original radio was 2G - I didn't upgrade it because they wanted $200, and I think the 3G replacement is also slated to disappear in the near future) While I wish I could remotely warm up the car or set the charging shutoff, it's not a huge loss. Most of the features continue to work perfectly fine.
But there exists a large group of people, especially here on HN, that want to execute a series of transport/car revolutions all in short order. There is the connected car, the electrification of cars, the auto-drive car, and the "end to individual car ownership". Many players in the industry want to push all those things to happen at once. Tesla actively pushes 3/4 of them. So it is natural for people to draw parallels, to see one revolution as integral to another.
Name one. Name one notable person here on HN who wants to "end individual car ownership". Not to offer an alternative for people who don't need to own a car all day every day, but to end it.
I don’t know who notable people here are, and don’t really care. The fact is that the opinion that cars should be banned/removed/made second class citizens is an extremely common and popular sentiment on HN.
You are correct, and all carbuyers should be aware. I know I will work with the service department of any new vehicle I buy to determine how to disable communication, if not faraday/RIP out the modem of any car I buy.
That said, I think a lot of non tech savvy people associate the two. My dad dislikes EVs for many reasons Fox News tells him to, but one of them is "self driving cars are never going to be safe or practical". He doesn't get that EVs can exist separate from Tesla self driving shenanigans, or that ICE vehicles are trying to do the same thing.
It was pioneered there. Not been able to buy a modern EV without it. Ostensibly for range anxiety early on, kept for the sweet revenue. The GM EV1 and Tesla roadster? were probably the last without it.
The most range-anxious person I ever saw was a tesla driver at a rest stop. A traffic accident had put us on a 150km detour though a different mountain valley, one without cellphone connectivity. He was at the first rest stop trying to figure out whether to push on or attempt to turn around and go home. He didn't have the range to go back, and couldn't figure out of there were any chargers 115km forwards at the next town. No cellphone coverage had turned him into a seething ball of indecision.
Cars have been running out of gas for 100 years, give or take. To refill an electric car you can usually just pull it with a tow rope for a few miles to recharge.
Doesn’t really seem like a seismic shift in paradigm to be honest. Certainly not to justify a different level of range anxiety than a gas car running a bit low.
>> Doesn’t really seem like a seismic shift in paradigm to be honest.
It really does, at least for those not living in big cities. It isn't even really about the range. It is about the limited availability of charging infrastructure, and I don't mean charge points. I mean that any gas-powered car can be "recharged" at the roadside. Someone can give you some gas. That isn't a thing for electric cars.
If a town must evacuate, a thing that does happen, you will want the ICEs vehicles that can be refueled quickly and easily in less-than-ideal conditions. A few years ago Fort McMurray Canada had to evacuate ahead of a wildfire. 80,000 people on the road in maybe 30,000 vehicles. The nearest town was over a hundred miles away, the nearest safe place maybe a hundred more. There were trucks handing out gas/diesel along the evac route to keep people moving. Such an impromptu evacuation would not have been possible using EVs. Evac situations also tend to coincide with loss of grid power (fires/hurricanes/flooding) which only further complicates the problem. Lots of people in small towns keep extra gas at home, or at least know how to syphon gas quickly between vehicles. EVs cannot do such tings.
> Such an impromptu evacuation would not have been possible using EVs.
This is, in fact, precisely backward. A fully charged EV will stomp all over a fully gassed ICE in a stop and go evacuation situation.
EVs don't have to idle. So, unlike older combustion engines, they don't use energy unless moving, and they recover most of the same energy when braking. At very low speeds, EVs stomp all over combustion engines. You don't need to refuel people because the EV isn't running out of gas from idling in stopped traffic.
More modern combustion engines turn themselves off. But, even that has its limits as you can't recover the start stop energy like an EV can.
This seems an absurd take but the absurdity is all in one direction - you can go the other way and maybe find reason again somewhere in the middle:
>> It is about the limited availability of charging infrastructure
You begin most days at home, do you need more than the charging infra? You start each day with the ability to drive 2-4 hours. Are you planning to spend more time driving most days?
An EV sat at home has 80% range. You don’t leave them fully charged usually, for the sake of battery longevity but you absolutely want any excess solar in your remote property being added to your EV rather than sent back to the grid.
That may be more range than the gas car sat next to it on an idle Tuesday when an emergency hits. Who keeps a gas car fully topped up at all times?
With an ev in a remote location, you start every day with 80%. That gas car you meant to fill up when you were next in town? Good luck because:
>> Evac situations also tend to coincide with loss of grid power (fires/hurricanes/flooding)
This means the gas pumps are off. They use electricity, plus the staff are evacuating anyway.
Need to cross a now flooded road? You might have to hitch a ride across in an EV, your gas cars intake might be too low and end up with the engine hydro-locked.
Just for the fun of this and mainly because the context for the comment to which you are replying is: "It really does, at least for those not living in big cities." let's address some of your points:
> Are you planning to spend more time driving most days?
Where I live in a sparse rural area, if you take a vehicle out it is very likely to be for a minimum of four hours, distances are large and any vehicles are work horses, if they're not travelling they're putting in an 8 hour shift (minimum).
> Who keeps a gas car fully topped up at all times?
We do, and most of our neighbours do, in our case this goes to my father who was born in 1935 and still keeps things "ready to go", be it cars, tools, spare generators, etc.
The vehicles are filled and there are spare jerry cans, full, in the sheds.
Our neighbours are ready to fight fires on five minutes notice, they've got tenders topped with fuel and water and all times, etc.
> This means the gas pumps are off. They use electricity,
What the literal F? - Sure they have electric motors but they (the local ones here at least) have attachable hand cranks not to mention the servo has a "generator" that provides "electricity" when the main grid is down.
> Need to cross a now flooded road? ... your gas cars intake might be too low
Say what? I cannot recall the last time I saw a 4x4 without a snorkel.
Sure, but with a gas car the typical response is to hitch a ride to the nearest gas station (which along any highway won't be that far unlike EV chargers), buy a small gas can, fill it up, and hitch a ride back. Sometimes gas stations even have a gas can you can borrow for free so your only extra cost is the time. Once in a while a nice person will even have extra gas in their truck they will just give you for free.
A tow truck by contrast will cost you $100 to get you to a gas station. Tow trucks are great services if the problem is more than out of gas (and some of them will bring gas for less, but you still pay for the service), but there are not what most people use when out of gas.
I'm assuming regen is designed to be used for short periods when slowing down, I wonder how long it can be used continuously.
Also, what would be the requirements for the towing vehicle? 70 kW of extra load is no joke, and car engines are generally not designed to handle heavy loads for extended periods of time.
The EV can handle it for a long time. I've never towed a vehicle like this, but I've gone down very steep mountains with nothing but heavy regen for over 45 minutes.
Some vehicles could maybe handle towing an extra 70kw (~100hp). You could always use a lesser regen level more suitable to the towing vehicle too.
It wasn't pioneered in EVs, it was coincidental timing. These features were always coming to all cars - but features start off in luxury vehicles, and EVs were priced in the luxury category. Go back and look at mid-to-late-2000s luxury vehicles and you'll find the features being developed there, even before the modern electric vehicles started showing up.
In general most auto manufacturers are trying to shift their revenue model from periodic auto and parts sales to monthly subscription fees. This isn't linked to EVs. They're trying to force consumers into subscriptions for ICE vehicles as well. This is obviously a negative for consumers, but subscription revenue is seen by Wall Street as more stable and predictable thus it supports higher stock market valuations and better bond credit ratings.
A world based on planned obsolescence is aligned with minimum cost optimized components.
It is of no interest for a company to just sell you a thing for cheap, not extract some sort of rent from it and for you to not replace it constantly.
In theory a revenue model based on subscription fees is also more aligned with the preservation of the environment and providing the end-user long term quality components, as to extract said rent smoothly and for as long as possible.
That of course assuming those subscriptions cover actual vehicle maintenance (somewhat like Managed Services Provider do for, say, printers), why not? Transportation-as-a-Service seems a very reasonable X-as-a-Service model .
See the Dacia Spring, not only it is an EV for about $20k, but if you look at the interior, you don't even realize it's electric. It is all knobs and dials, some models are equipped with a screen and GPS for navigation, but you won't get more than that in term of connectivity.
They have the instruments cluster that looks like a Christmas tree.
Giant colorful "econometer" that screams like "some manager wanted to put an ad to remind you how efficient the car is" that has questionable usability, especially compared to its size. And right-hand side displays a red-colored last block even when the tank is not empty, messing up color coding. It would've made more sense to apply colors where they matter, like on the speedometer when you're going too fast, or when the car is in reverse.
Why can't most car vendors hire someone with a brain for a UI designer?
That sounds great, but I'm a bit sad that it seems to come only in SUV form factor. Do you happen to know if they have anything in less obnoxious sizes?
Spring owner here. It's a cool little car. The main disadvantage is that AC recharging is extremely slow (6.6 kW three phase) because they skimped on battery cooling. And opening/closing the doors feels more like a 1990 Fiat Panda. It obviously doesn't go fast on the highway but in the city it's great, the electric motor gives it surprising acceleration for a 33 kW engine.
It's 3.70 meters long, definitely not an SUV. It's not only the smallest EV (the Volkswagen e-UP is unobtainable at least in Italy) but one of the smallest cars in general.
According to the regulation, the eCall is only activated as the emergency is triggered (as the airbags trigger). According to what you can expect, it is hard to know if that is the way the manufacturers implemented it.
I worked for an automotive company for a while and I recall a meeting wherein were learned about compliance, fault, maintaining records, etc. One thing I learned is that you do not know how far lawyers will go to reach a verdict or a settlement. And if you're reading this right now, I will tell you do not know how far a lawyer and their clients will go to reach a settlement. And that's lawyers on both sides of any argument.
If you ever have an opportunity to attend a training/info seminar put on by legal, I promise you it is way more interesting than it sounds on the face of it.
gasoline powered cars are a privacy nightmare too and a terrible "its all going digital" nightmare. the problem here is obviously oppression by the majority
That isn't the only real problem with trying to have privacy with your car. And, realistically, this isn't new. It was common a long time ago to know that so and so was at someone's house because you saw their car there. Or you saw their car really anywhere else.
And with how traceable cars are, the idea that it has to do the data sending for you is a bit outdated. If it was ever accurate.
This seems like a non-sequitur? Cars can't track your every movement. But that phone in your pocket is already doing that. Even if it isn't recorded by the phone, the cell towers that your phone is in constant communication with to actually work can do so. Add in the ridiculously lax methodology we took for bluetooth scanning and connection to work, and you leak more information than your car can do well before the car gets internet connected.
Don't get me wrong, I'm a bit concerned about internet connected cars, too. But privacy seems a weak angle there. I'm much more concerned with safety than I am privacy. I fully expect that with all of the license scanners that exist today, if the government wanted to track my movements, that ship sailed a long time ago. I'm not convinced that having the ability to connect to my car from remote is at all safe. Especially to the control facilities.
Cars already have a black box like logging system that tracks literally everything the car does continuously in very fine detail. The exact speed and engine load, brake/throttle/steering input, detected tire slip, elevation changes, body roll/pitch/yaw. With that data alone, it's pretty trivial to construct a very exact route, and it's not difficult to figure out where that route fits on a map. Manufacturers already use this data to deny warranty claims.
Vehicles having GPS, compass, cell service, bluetooth, and WiFi just makes that tracking trivial. All that's currently missing is the internet connectivity to upload the data in real time instead of the data being pulled at maintenance. Many manufactures also do have background data upload over cell service, even if they don't expose internet features to the vehicle owner.
Right, I didn't mean to make that sound completely hypothetical. I am assuming their are not regulations on the retention policy of these, though. And, that I think I could support. I'd be fine with disallowing those from being connected to a transmitter. (Though, even there, I can see carve outs for 911 style data assistance. Physical safety may actually be improved with sharing some of this data.)
And, again, I also know it is pretty trivial to recreate exact routes from relatively low powered phones and watches. Because I do that on the regular for cycling and such. I haven't seen a ton of articles worried about the privacy nightmare of smart watches, though? (Mayhap I've just missed them?)
The difference is cars aren't comparable to phones anymore. They're already way more capable than phones with always on cameras with sonar and radar mapping in multiple directions, always on mics for voice commands, and even continuous driver face scanning.
Those are also things that are also usually logged, those are things most people probably don't want to be continuously uploaded and recklessly exposed.
Phones have always on mics for voice commands, as well? The camera sensors are probably new, but likely not as new as you think they are. For a fun example, consider this site: https://web.seattle.gov/Travelers/
And your phone is much more directly linked to you. And can probably track you through buildings quite easily. Worse, probably makes you trackable to anyone that wants to, for example, watch for your phone's bluetooth id to pass by.
To be clear, the cameras around the car, I think, is mostly a good thing to consider in more depth. Though, again, I'm not too clear on what makes these unique for being on the car. If someone was to stick a camera next to their mailbox, I'd expect they would also be limited in what they are allowed to do with the images they capture.
Again, though, if you are at all worried about your privacy of data collection, watches and phones are far more of a concern than your car.
Just to explore the idea some more, how much of what can be learned about you from the car, cannot be learned about you from looking at cell tower logs about where your phone has been? Heck, for most of us, looking at where you have scanned your credit card is already more than enough to construct when and where you traveled throughout the day. The wifi history of your phone is probably good enough, as well.
With phones and fixed cameras, people have to make a deliberate choice to point them at something of interest. If your neighbor decided to mount a camera that always looked into your bedroom window or yard, you probably won't be very happy about it, but you also know they had to deliberately do it and likely know the area they're monitoring.
Now with phone cameras, it's more likely than not that it's not looking at anything interesting most of the time, since it'd be lying flat on a surface or in a pocket/bag.
Car cameras are specifically designed to be very good at detecting people, since their primary purpose tends to be pedestrian avoidance. They also tend to not be obfuscated and have great vantage points. That makes them very likely to see something interesting, with very strong signal for how interesting it is. And the intention of the vehicle owner doesn't have to be aligned with the manufacturer.
Let's say you're a complete luddite with no power, phone, car, or internet of any kind. If I were, say Tesla and you were in a major metro areas, I could probably still construct a pretty through understanding of you or your home just from various Teslas driving or parked in your area. We can even go full facial or body recognition and figure out where you are from your appearances on their vehicles. How distinguishable are you from video+sonar+radar identification? How feasible is it to hide from sight from every car?
It's like how Facebook or Google can create a profile and understanding of what you do, without you ever touching any of its services, because it's practically impossible to use the internet without touching a service that'll feed information to them, or stopping everyone who knows something about you from disclosing that information to them.
And, really, if you want to know what someone's house is like on the interior, you can probably just look it up at the local planning office. Often for free. And this isn't even getting into the people that have vacuums that map out the place on a somewhat regular basis...
Look, I get it that this is yet another vector for information. I just can't bring myself to think it is a meaningfully worse one than any others. If you view it as "cars are another item on the nightmare that is modern privacy", I fully agree. Thinking they are somehow more capable of surveillance than basically every other one that has proliferated in recent years feels off.
You've misunderstood the situation completely.
The first job of a persistent attacker is to gain acceess.
The second job of a persistent attacker is to pivot that access from illegitimate to legitimate, so that by the time their TTPs become IOCs, log rotation has wiped that illegitimate access from the books and all their access looks legitimate.
What we have here is a way for an attacker using shady means (email-delivered 0day, parking lot thumbdrive, browser drive-by compromise) to take over a computer and then drop a signed package that will allow for remote control over time that looks completely legitimate. To a network IDS, that access will look like an authorized cloud tunnel, completely normal. To a file scanner, it will look like an vendor-signed binary, the gold standard. To the complete defense-in-depth stack, the entire c2 chain is cloaked in legitimacy. If you get a single detection at all for the initial compromise (not possible with 0day), the entire rest of the kill chain looks like legitimate access and vanishes.
It's a nightmare for defense in depth and hunt teams.
I'm assuming they mean the balance mechanism, and specifically what allows us to balance. How much is it the rider shifting their weight, how much is micro steering adjusts as we move forward, how much is the gyroscopic forces of the wheels, how much of it has to do with the angle of the handle bars to the wheel verse the center of weight.
That said, I'm guessing this one is well understood by experts, but more complex than someone would assume at first glance, and many who have some understanding likely have an incorrect or at least incomplete understanding of how balancing works.
You are correct, a lot of forces are canceling out on the long term(instead of instantaneously) it can easily be manipulated into increasing periods of unbalance in one direction until a point is reached then a separate mechanism is used to force it to a balanced state. Conservation of energy is always in effect. Gyroscope effects that bike wheels can be added with other separate gyroscopes. Thus, a self righting bike. The effect called precession is understood well enough.
How a human is able to manipulate it is simply by using the force of gravity from shifting their weight(moving the center of gravity). However, the movement of the center of gravity has to be perpendicular to the wheels axle. The steeper the angle of attack the wheel has to the ground, there will need to be an exponential increase in distance to move the center of gravity. Once the wheel is parallel to the ground, there will be an undefined distance needed to move the center of gravity.
The smart phone is the culmination of understanding a million facts about materials sciences (applied and theoretical), some of which were obvious, some of which were non-obvious. Starting from a transistor you could see from across the room down to ones you can't even see with a magnifying glass.
It's the reason I got a degree in physics, if you have good professors - discussions like this cause you to break down the problem quite quickly in your head in a working model. Think force diagrams, but with a ton more math backing it up.
I actually find the ice skate a better example than a bike. We have all the physics solved for bikes, it's a complicated system but so is everything in motion. Hence we assume a spherical cow for the sake of the problem.
But ice skates... Now that's a funky one. Why do ice skates works? Ice skates aren't sharp bladed, they actually have flats. Ice is not slippery, it's when something is on ice in between our shoes and the ice that cause it to be slippery. Some people think it's the localized pressure of the blade that causes ice to locally melt. Hard to really wrap your head around. But it works :)
>We have all the physics solved for bikes, it's a complicated system but so is everything in motion. Hence we assume a spherical cow for the sake of the problem.
This depends upon the question one is trying to answer. If one is trying to create a bicycle that can self balance, that involves considering different factors compared to trying to determine why certain injuries result in a person losing the ability to balance on a bicycle while others do not. Is the focus the bicycle or the human?
e.g. What keeps bicycles balanced with or without a rider is still an active area of research, and even the seemingly basic idea that, for a bicycle to be self-stable, it needs to turn the handlebars into the fall, has not yet been proven.
You can write out the equations of motion for a bicycle that will very accurately predict the dynamics. You can put these equations into a numerical simulation and predict motion very accurately. You can change the parameters of the model and do simulations with high confidence. Just because there isn't some neat little equation that says exactly what each parameter change is going to do (without doing the simulation) doesn't mean that we don't understand bicycle physics. It's a silly line of reasoning. Those articles are hyperbolic.
There are things we can characterize to any desired degree of accuracy but that e don't get cute little equations out of... and some of those things are so simple they've been staring you in the face since middle school and you just didn't ever notice their absence from your formula sheets.
This is not the exact same situation being described but it's a similar thing. Being able to put a complex system into a computer and arbitrarily manipulate it still doesn't mean we can extract some simple explanation.
On the other end of the scale, see all the AIs coming out. They're 100% computer artifacts with theoretically no mystery in them whatsoever... but they're just tables of billions of opaque numbers and doing anything with the numbers beyond just running them is amazingly difficult.
As a bit of an aside, most people don't know how bicycle wheels work. There's a whole section in https://en.wikipedia.org/wiki/The_Bicycle_Wheel that talks about how they actually work. It's not tension at the top, it's compression on the bottom.
what do you mean it's not tension at the top? did you misspeak? bicycle spokes are solely under tensile forces. they can't support compressive forces at all. i'm a hobbyist wheel builder and a once upon a time professional bicycle mechanic during hs & college.
if you want to test this take nearly all the pretension out of your spokes and sit on your bike. feel which ones are taught and which ones are completely loose. or just go to walmart. those bikes hardly have any pretension in their wheels.
This dialogue is reminiscent of rec.bycycles.tech arguments with Jobst, ca 1993.
A bike wheel is a linear elastic system, that can be thought of as a superposition of a uniformly set of tensioned spokes as one state, and a set of spokes in compression in the loaded zone (bottom of the wheel) as the other state. So long as the superposition of the two states obeys the limiting conditions (i.e. spokes in tension) they can be analysed separately.
The size of the loaded zone is related to the relative stiffness of the spokes (axial) and the rim (bending), and can be calculated using beam on elastic foundation methods. For typical rim/spoke combinations, this is approximately 4 spokes.
Outside of the loaded zone, spoke tensions essentially don’t change.
Pretty sure he did, but I don't have r.b.t. archives. He was definitely a proponent of them, preferred a specific brand/style, and would have easily been able to do the experiment.
Well. I wish we could sit in front of a bicycle wheel and discuss it. Because I have a feeling we are shooting arrows at different targets. As a mountain biker I'm more interested in what happens when an extreme amount of load is applied to the wheel, not the model with assumptions applied. Definitely a difficult concept to discuss with only text. Anyways.. glad to have a good discussion with you about bicycle wheels. Don't find many people like you. :)
I think I would have been a mechanical engineer if I were born 20 years earlier or 20 years later. Software was just new and shiny enough and it let me build things with my mind, at a time when I believed I was clumsy (I actually have always had excellent fine motor skills, it's macro motor control I lagged behind in). One of my better friends in college was an ME. Learned all sorts of things about metal fatigue and oddly enough picosecond lasers from him.
I don't know if I found Lego or Lego found me, but I definitely think in terms of shapes. I was past my midlife crisis before I realized that I don't have a large working memory (smaller than average in fact) it's just that I've been doing mind palaces without pictures since I was very small. When I'm thinking of large computer systems I'm essentially thinking of them as physics problems.
I really should figure out space to have a bike again. I never rode when I lived in Seattle (Seattle drivers are nuts) but I don't live there anymore and I need to catch up on 20 years of tech.
I think you're both in violent agreement using different terms.
You're looking at the macro "It's all in tension" (superposition of two states) and hinkley is looking at the "bottom is a compressive change" (dynamic portion of the load).
What I'm not clear of is if you think that the upper spokes change tension between the unloaded case and the plain gravity load case (force on hub down, ground on rim up at the bottom), or if you expect the top half spokes to increase and the bottom half to decrease in tension. I think this is what hinkley thinks you think.
That was indeed my interpretation of that half of the conversation. That they were claiming that the axle is suspended (tension increases with downforce) by the spokes above the midline of the circle, which is what Brandt vehemently contended was false.
That book I linked has another name, “the wheel building bible”. Jobst Brandt earned an obituary in Bicycling magazine including quotes from his friend Tom Ritchey (one of the original mountain bike makers). Jobst was a bike fanatic and a mechanical engineer.
Bike spokes are not loose, they’re under substantial tension. Bolts, I just learned a couple weeks ago, work in the opposite way. A tightened bolt compresses the two pieces of metal together, and when you tug on them, the bolt doesn’t stretch more. The tension instead first cancels out some of the compressive force on the two pieces of metal, before the bolt ever feels more load.
Conversely, all the spokes on the wheel are under tension. When you put the wheel on a surface and push down, the compression cancels out some of the tension on the bottom of the wheel. Cancel out all of the tension, and the wheel turns into a potato chip if you don’t reload it exactly, perfectly on axis. IIRC, none of the prior models or theories for how a spoked wheel works could adequately explain how potato chipping happens. His does.
I used his book to build half a dozen wheels or so and the information it contained to fix many more.
i own the book.. and also The Art of Wheelbuilding - Gerd Schraner
of course in a properly built wheel usually all the spoke are under tension...
i was just demonstrating the fact that the spokes on the upper half of the wheel are supporting the hub and are under greater tension than the bottom ones, the spokes on the bottom half of the wheel should remain in tension, but only through the fact that they are already under tension applied during the building of the wheel.
the fact that the wheel works by tension of the spokes becomes obviously apparent when you start to remove the pretension and then the spokes will feel loose on the bottom half. of course you'd never want to ride a wheel like that because it will quickly become out of true.. just like a walmart wheel.
I think one of us needs to reread that book, because he emphatically denies that tension at the top of the wheel increases. It’s tension at the bottom that decreases.
> of course in a properly built wheel usually all the spoke are under tension...
No, a properly built wheel all of the spokes are always under enough tension you can bounce a penny off them. Always.
no. you're assuming the rim has no deflection which is untrue. if you build a rim out of schedule 80 steel pipe then yea. but 300-400-500g rims on high performance bikes do not act like that. the spokes are constantly loading and unloading tension as they bash through rocks and over jumps. the point is that the pretension on the wheel needs to be high enough the spokes do not loosen too much under these forces. if they do in fact loosen too much the nipples will begin to loosen and unwind and the wheel will become out of balance.
If you’re talking about twisted spokes unwinding, you don’t have to reach zero load for that to happen. You just need to reduce the load enough so the rotational force overcomes friction. Tension will also try to unwind a screw as well. But the thread pitch on spokes is very fine, which lessens that force. If you build spokes like wood screws we would have problems and that has nothing to do with reaching 0 newtons.
You can release a lot of those tensions by squeezing the spokes mid build. Just don’t wait until they’re too tight to do it. I had a pulse in my rear wheel that probably came from doing that wrong the first time. Unless it was a factory defect, I must have overtensioned and warped a brand new Mavic aero rim ever so slightly. Expensive lesson, but it could have been worse.
I wonder if those have less or more breakin issues compared to spokes. With a spoke you have to reset the angle of the bend to the shortest distance between the hub and the rim. But with cables they have to settle in along their entire length.
Doesn’t change the answer. They’re still compressing. They’re just pretensioned.
There's a lot more creep early on, which is compensated for by a staged tensioning over the course of a few days. They may require the spoke holes in the hub to be radiused, which can be a warranty issue between you and the hub manufacturer. Windup is controlled by a flat on the small bit of spoke used for threads.
They're ok (i.e., made it through Tour Divide with no issues), done well they're certainly better than badly done steel spokes, but it's not clear if the best builds are better than the best steel builds.
There are two situations when you can push on a string. One is when it’s frozen, and the other when it’s tensioned. How do you unload a bow string? You push it off the notches.
bro. you're wrong. just build a bicycle wheel some time. it becomes very obvious how they work as you take it through the various stages of tensioning.
Why do you think someone would talk about Brandt’s work if they hadn’t used it?
I’ve built more than half a dozen bicycle wheels. My set, my spare that my brother road (into the ground - my first set and practically the only problematic ones, but he road over bumps without getting out of the saddle), a set my dad commissioned from me, and a pair that he had me build for a friend. All by age 17.
I then worked as a mechanic for two summers of college. I was never the fastest, but if we had a customer we could not afford to disappoint, I or the senior mechanic got the job because my repairs did not come back.
I saved three or four wheels that would have been scrap by unwinding the spokes halfway and building it back up again like a wheel build. Only added an extra ten or fifteen minutes but it works a charm. When a good customer comes in on Wednesday before an out of town bike ride you can’t afford to fuck it up. I think I only built a couple professionally, and usually singles. That’s a lot of labor and few will pay.
The world is full of papers that are wrong. Including maybe the one this whole thread is about. It’s okay, it happens. Science doesn’t find right or wrong, though a lot of people think so. It finds more wrong and less wrong.
Without working in the industry, how could someone vet for the internal cybersecurity of an upcoming car purchase? None of these security features seem to be publicly documented anywhere. I have spent a long time looking.
You can't. Heck, it's sometimes hard to tell even when you work inside and have all the docs. The best information you have is to look at the manufacturer's past history as evidence for their future security competence.
Manufacturers also aren't building every piece of software on a given vehicle. Many components will be done by suppliers that range from "meh" to "wtf" when it comes to security. Even the best reviewers will struggle to catch everything a sufficiently incompetent implementation screws up.
