Parasitic bike pump steals air from car tires


People who enjoy getting mad will enjoy getting mad at Instructables user Aleksi for making this emergency parasitic bike pump that steals air from car tires.


  1. More like an air donation system: My bike tires are at 100psi, and most cars are around 30-40 right? This would deflate my tires in an instant.

      1. Correct, it’s basically a set of clips with a valve so you can achieve equilisation of pressure. If you are evil, you could nick another bike’s high pressure air, though ;)

  2. Given the pressure car tires run at this might not work that well. I wonder if you could swipe pressure from trucks?

    A good one for the urban cyclist is a presta->schraeder adapter and a few quarters so you can fill up at any gas station (who’s air pump happens to be working…). That, some patches, and a couple tire levers will get you out of most flats with a kit smaller than a deck of cards and under $5.

  3. It hardly matters whether or not it works: as an object, it’s sole function is to be the perfect metaphor for the arrogant sense of entitlement exhibited by your average bicycle commuter.

    1. It hardly matters whether or not it works: as an object, it’s sole function is to be the perfect metaphor for the arrogant sense of entitlement exhibited by your average bicycle commuter.
      Well I’m that bicycle commuter so what issues do you have with me, specifically?

      1. Since you asked…

        Bicycle commuting isn’t a viable transportation option for a city. It’s a lifestyle choice, like sadomasochism or perhaps some sort of cult that ends in beverages sweetened with cyanide.

        The city I call home – Vancouver – is currently spending millions of dollars tearing up downtown city streets to convert car lanes into bike lanes. The downtown grid used to be relatively well balanced: it’s now a nightmare. Everywhere I look, kilometers worth of nearly empty bike lanes, put there to enable an ideologically-driven lifestyle choice masquerading as a solution to global warming, foreign oil dependence, and the really sad cancers that little kids get.

        None but a small minority want to get on their bikes (especially in a city with 166 rainy days per year) to get dirty and sweaty while getting to their destinations at a third the speed of a powered vehicle. Funny then that the latest fashion is to dedicate a third of the road grid to cycling.

        1. Do yourself a favour and don’t prepose to know everybody’s motivations and ideologies, let alone judge and dismiss them. Here in Calgary I know plenty of people the cycle to work IN the oil industry. We’re not under the impression it’ll be the end of oil. We’re under the impression that it’s good exercise and saves us hundreds a month in parking, gas, insurance, and maintenance.

          If all the bike lanes are empty then obviously it’s a pretty viable method for getting to work if you’re on a bicycle.

          And comparing speeds is a bit of a red herring. A third of the speed, and a lot less then a third of a tenth of the price – don’t leave that part out. As for sweat – it’s healthy and enough people don’t mind. You can pretend that because so many more people drive there just isn’t the populist support for the bike lanes, but in practice that’s obviously not true seeing as how people seem to keep voting in favour of these measures.

          And another thing – there are plenty of cities without any bike lanes to speak of that still have massive traffic jam problems. So how come that makes bikes unfeasible instead of making cars unfeasible?

        2. Okay so somebody posts a picture of an interesting tool. One which I could use to quickly inflate one of my bike tyres from another vehicle, for example. So you jump on that and blame bike commuters (including me) for traffic engineering practices in Vancouver.

          For your information bicycle commuting is viable and practical for many people. I do it all year round, in all weather.

        3. I also call Vancouver home, and commute 25km every day by bicycle in all weathers. I don’t do it for the environment, I do it for myself. Don’t pretend to know my motivations. To blame the bike lanes for the traffic chaos is idiotic. And they are certainly not “nearly empty”. The bikes are the solution, not the problem.

          “Cars ruin everything I love”.

        4. Bicycle riding is definitely not a viable option for a city by itself. The majority of people must be taken on by mass transit such as trains, and then bikes will be able to help with the remainder. If you don’t have good mass transit, though, don’t blame the bikes for your traffic.

        5. Another bicycle commuter here, and a broke-ass college student as well. I don’t have the $700 per year that I’d have to fork over to the school for *just the parking permit*, *not counting* gas and maintenance for the car, and my college has such a bad parking shortage that the only place I can find parking at 8 a.m. is a 15-minute walk from my class. I’d *love* to have the kind of cash that’ll let my bike commuting be driven by ideology alone. (Though now, I’ll probably try to continue to commute by bike – it’s good exercise and stress-relief, without having to go to the gym.)

          No, it’s not nearly as convenient as having a car. There’s a humongous hill between where I live and the campus, and after a year or so, I finally got sick of climbing the damn thing every morning. The solution? Buses with bike racks. I bus to school in the morning, then bike back in the evening.

          If bike commuting isn’t a viable option for most people, I think it has more to do with lack of infrastructure for bike commuting than anything else.

          About the pump itself – I wouldn’t own one, but I think the idea’s kind of hilarious.

        6. You’re a fool. I cycle in London, because I don’t want to pay through the nose for useless, stressful public transport. It’s everyone owning a motor vehicle that is not viable in a city like London – the street system – much of which is mediaeval in origin, isn’t capable of supporting the volume of traffic that uses it. So in that sense, more bicycles would actually improve the situation. Of course there are some kinds of vehicle which are necessary – buses, HGVs and vans or their equivalent are always going to be a necessity of a developed economy as far as I can see. All of those single-occupant cars are not.

          Regarding the sense of acrimony between drivers and cyclists; It’s not hard to see why it exists. First of all, a proportion of drivers feel entitled to the road, firstly because they don’t realise that it was cyclists who got the road system improved to the point where cars would be viable, and secondly because they often think that they pay ‘road tax’ which pays for the infrastructure. This is actually (in the UK) false – they pay vehicle excise duty, which permits them to use the road and which does not, and has never, directly paid for roads. We all pay for roads, even those of us who walk everywhere or only travel by train. this, in combination with a more atavistic belief that smaller, more vulnerable road users should get out of the way (similar to that which HGV drivers often exhibit towards cars) leads a certain proportion of drivers to operate under the assumption that all cyclists deserve to be taught a lesson. And many cyclists react in kind – they aren’t treated like legitimate road users so they don’t act like legitimate road users. This is of course just as wrong.

          I’ve experienced dangerous, rude and intimidating road use by drivers, but I try to remember that that’s one individual driver, and continue to treat other road users respectfully. If possible I try to let drivers past if I’m holding them up (in a city like London that’s less common than you might imagine – I’m often faster than the rest of the traffic flow) and I try to acknowledge considerate driving – even when it a situation where strictly speaking the driver would otherwise be in the wrong – for example if I have right of way. It’s simply that I want to acknowledge when people are driving in a considerate manner. I also never jump reds. Often, it wouldn’t be dangerous, but when accidents occur the assumption is so often that the cyclist must have been in the wrong, that I don’t want to put fuel on the fire in that respect.

          In short, syncrotic, I think that you and mokey probably deserve each other.

          And since my post is way off topic, I think that the parasitic bike pump think it a bunch of ass as an idea, and further would probably not work. I run 110 PSI. I have been tempted by those little C02 pumps, though. I get punctures really regularly, and my hand pump often breaks my valves because it’s so unwieldy. but if the little 16g vessels probably don’t fill many inners before they are empty, I’m not sure that it would be cost effective.

    2. As opposed to Car commuters of course….. who not only get the government to build an entire interstate system for them, a near monopoly on nearly all road and transportation designs, but also get subsidies in the form of support for the auto industry…… But hey bikers are “arrogant and self-entittled”. Car infrastructure = a given (ie an “entitlement”), but bicycle infrastructure that’s barely a pittance in most cities, that’s expecting too much….. right.

      If there’s one thing I’ve learned about those who beak about “entitlement”, they’re usually those the most oblivious to their own privileges and the most selfish when it comes to responding to any suggestions of sharing – as in the road.

      FYI – I drive to work, and I carpool.

    3. Oh, are you referring to our sense of entitlement to use the roads that we are entitled to use? Did you ever think about your own sense of entitlement to dirty the air with your vehicle exhaust because you are too lazy to travel under your own power?

  4. I’d call it a device to steal air from road bike tires to fill your car tire, but you have to steal air from *a lot* of road bikes to make it worthwhile.

  5. I’d hate to see what would happen to the bicyclist caught siphoning air from the truck of one of the teamsters I work with. They’d be lucky to just have their bike run over.

  6. They took over the roads by killing and maiming other road users. So what’s a little air?

    And would it really not work? Sure, car tires are only at a third of the pressure of road bike tires, but a) there’s a significantly greater volume of air there, and b) you’ve got the weight of the car helping to push it out. Having pumped up car tires with my bike pump before, I’m not so sure it wouldn’t.

    But questions of efficacy and ethics aside, a CO2 cartridge and the little thingy that screws on to the top of it takes up a whole lot less space in my tool bag than this would. (And, much like myself, doesn’t require a car.)

    1. I remember that day in drivers ed when our instructor pointed out how to best maim and kill other road users. He brought in a necklace made from the finger bones of cyclists he’d run down over the years. Ah, memories.

      Take it down a notch and lets share the road, ok?

      1. I just realized your comment could be read in two possible ways, so please accept my Schröedinger’s Apology.

    2. Oh god, this comment is making me rage. Yes, the weight of the car is helping to push it, but obviously the 40psi includes that force.

      Also there’s no way that a CO2 cartridge could do anything for a flat bike tire. There isn’t enough equivalent mass in a tiny cartridge to pressurize an entire tire.

      1. I phrased it in such a way to indicate that I simply wasn’t sure. I’m going off mostly anecdotal “evidence,” i.e. having inflated more than one of each type of tire with the same bike pump. And let me tell ya, if you can get a 205/60/15 tire up to 30psi that way without taking two breaks, you must do a hell of a lot more pushups than I do.

        As to the CO2 cartridge, yeah, they work. A 16 gram cartridge will inflate a wide mountain bike tire to ~40psi, or a skinny road tire to ~100psi. And at an alarming rate, I might add.

        1. The retarded comment about air pressure aside, I had an interesting lesson about car tire pressure last week when I repaired a tire. After re-inflating it while off the car, I put it back on the car only to find that the air pressure hadn’t changed pretty much at all.

          But it makes sense – It’s ideal gas law. Pressure * Volume = Ideal Gas constant * number of particles * Temperature. All the car is going to do pressing down on the rim when mounted is change the volume, and the pressure will rise proportionally. If the tire is fully inflated, it’s not supposed to deform when on the car (ideally, although it does just a little bit), meaning no volume change, meaning no pressure change. Sure if you have a whole in the tire, the car pressing down on it will “sqeeze” the air out of the tire, and the volume will change, but really the weight of just the rim can do that too.

          At the end of the day, the pressure is going to equilibrate and that’s it, 30-50psi still represents that maximum you can get out of the car tire, the only thing the effect of the weight of the car will do will be to effectively increase the volume which will come out before the pressure drops in the car tire.

          Really, I have a pocket pump that will do even 50 psi in less time that it would take to sponge off a car.

          The best use I can see for this device – ironically enough, is for motorists. Like jumper cables for tires. Sure then you both need to find a service station, assumingly your 40 psi tire, if completely flat, will be now at 20 psi and so will your helper, but you can drive on that. It would save changing a tire and all you’d need to recover from a flat would be this and one of those little $10 “tar snake” tire repair kits. (or better yet you can just inflate the flat with one of your other tires).

    3. You’re the sort of guy who’d use a plastic bucket as an anchor because it’s bound to work because it’s full of heavy water.
      I think you need to go back to science class.

      1. I never claimed it would work. I said I wasn’t so sure it that wouldn’t. I was trying not to simply assume that the obvious answer (100 > 30) is automatically correct. In this case, the obvious answer was correct, and my skepticism wasn’t. But questioning my initial assumptions keeps me from looking stupid more frequently than it causes me to look stupid, so I’m gonna keep doing that. Even if I get one wrong occasionally.

  7. Gadget bloggers who enjoy getting mad will enjoy getting mad at their commenters with bikes and 9th-grade physics.

  8. If you ride a mountain bike with relatively wide tires, this device would give you adequate pressure to continue. I’m not sure about the volume of air lost to the car tire, but I suspect it’d be driveable as well.

  9. Note the word “emergency”. This isn’t for topping off your tires; it’s for inflating them to a rideable pressure long enough to get to a pump. Useful, presumably, if you’ve just discovered a slow leak after a day at work, or just changed a tube and found that a crucial piece of your portable pump had disappeared while riding (which happened to me). I usually ride at 50psi; 30-40 would be perfectly adequate for a mile or two.

    It also doesn’t have to be asshole gear. There’s nothing stopping you from asking someone who’s getting into their car if you could borrow a little emergency air — the volume involved would be so small the car would barely notice.

  10. You guys are all maroons. OBVIOUSLY, this devices is intended for CAR OWNERS. If my tire is running a little low, I pull up to a bike rack, drain every bike at that rack, and move on. It doesn’t do a whole lot for my car, but at least a whole lot of other people get to share my misery.

  11. The existence of this object is a well crafted, multi-level troll on car users, bike users, people who understand physics, and people who don’t understand physics. Well done.

  12. Bicycle commuting isn’t a viable transportation option for a city. […] None but a small minority want to get on their bikes (especially in a city with 166 rainy days per year) to get dirty and sweaty while getting to their destinations at a third the speed of a powered vehicle.

    I started biking to work this spring. My 7.5-mile commute on a bike takes 40 minutes. Same commute via public transportation: 60-75 minutes. Same commute via car: 25-30 minutes (outside of rush hour).

    I live in Boston. 2/3 of my commute is on a nice protected bike path along the Charles River. It’s gorgeous. I get to work feeling cheerful and invigorated, instead of cranky and impatient. I’m saving money. I’m in decent shape now, and I’m a 38-year-old geek who’s never played a sport.

    Sounds viable to me! I think there are some cities in Europe that’ll disprove your thesis non-anecdotally, but then Europeans are tougher than Canadians. Apparently.

  13. I suppose a kind motorist could offer to give the cyclist a lift to a service station for air. But that would imply motorists and cyclist could get along. Ridiculous concept.

    1. Also assumes that said motorist has space in their car for a bicycle- that may be the case in the US, but certainly in Europe most cars can’t carry a bicycle unless it’s on an external rack or the rear seats are folded down. If you’re not carrying a bike rack and you already have people or stuff in the back of your car, then the cyclist would have to remove the wheel with the flat, leave the bike by the side of the road, and expect the motorist to give them a lift back to their bike as well…

    2. Actually, that did happen to me once. Young guy, probably late teens/early 20’s. Was walking his bike along the sidewalk and asked if I’d give him a lift to the gas station. I said sure, so we tossed his bike in the back of my Jeep and I dropped him off at a gas station a few miles away. No animosity, no smugness or anything. It never occurred to me at the time that there was any reason to be that way. No money changed hands, nothing. It’s just basic decency in action, that’s all. I wasn’t aware of the car/bike hostility until I saw it online.

      All I can say about that is, if your lives are so easy that this is all you’ve got to fight about, then that’s pretty amazing. We have hungry and homeless, unemployed, decent people all around my town. They sure could use a little help from you folks enjoying the easy life. I mean, if you can stop squabbling over bicycles and cars for a few minutes. Lord knows we here in reality would hate to interrupt such important business.

  14. A bike pump?

    A hack?

    These have been around since the invention of air pressure tires. They have traditionally been used to equalize air pressure in the case of a slow leak and to get a few miles to the service station (archaic for an establishment that used to provide gas and mechanical repairs that were the predominant place to procure gas as we do at gas stations today). I have owned more than one in the distant past.

    And, regarding unauthorized use, yes you are liable for all the consequences that go with letting the air out of someone’s tires.

  15. After reading these posts, I’ve decided most of you should forget the hose and should just go blow yourselves.

  16. Regarding the issue of weight increasing the air pressure, from the make page comments:

    Dunhausen says:
    What you can do is pile weight on the car first thus increasing the pressure. Just looking at my jeep it has, say, at least 80 in^2 of tire in contact with the ground. Of course, the tires will flatten out even more as you add weight and/or suck out air, but let’s say to get from 40 psi to 110psi you only need to pile 5,600 pounds on top of the vehicle for an adequate pressure increase. So with a good supply of bricks and rocks you should be in business.
    Nov 1, 2010. 2:58 PMespdp2 says:
    Maybe that’s why some &%$# piled a bunch of rocks on my Suburban! I was wondering, until I read this ‘ible.

    I both drive and bike and where I live bicycles are looked on as being for the pavement not the roads. Meaning drivers who see themselves as “pros” will often behave in a manner they don’t when I’m in the car. I’m talking about things like cutting you up to the point of forcing me to brake to avoid hitting them, driving down narrow roads without stopping for obstructions on their side expecting me to get out their way even though this is no passing space, cutting the centreline to emphasise I’m not as far into the side of the road as they think I should be. The situation of course isn’t helped by the fact you often get idiots cycling the wrong way along the inner lanes of six lane roads whilst composing text messages on their cell phones.

  17. When bicyclists are paying $150 per year (per bicycle) for registration fees, then they can carp about how cars are getting some kind of free ride. Until then, if they will just stop at the friggin’ stop signs like they’re supposed to, my car and I will make a genuine effort to stay as far away from them as possible.

    1. Just to be clear, did you mean:

      “When I see a cyclist running a stop sign, I make less of an effort to give that particular cyclist lots of room on the road, but otherwise I give cyclists respect”


      “As long as I see at least one cyclist a year disobey a traffic rule, that’s enough to reinforce my stereotypes, and I will continue to drive in a way that endangers the lives of all cyclists. After all, they all automatically share the blame for that one guy who just slowed down for the stop sign that one time, and an extrajudicial death penalty is suitable for belonging to a group that contains some people who commit misdemeanors.”

      Just asking, since it sounds like you drive a car, and as you probably have noticed, not all motorists obey all the laws all the time either.

      1. Here in NorCal most of the cyclists I see run stop signs. Most of them, not some, not once in a while.

        If they’re wearing Spandex and a fancy jersey you can pretty much count on them blowing through the 4-way without even slowing down. I’ve seen a young woman with a child in one of those tow-behind trailers run a stop sign- endangering not only herself but the child as well.

        Ignoring traffic laws while driving a car is bad enough, but at least the car will protect the occupant to some degree. But on a bicycle one has no protection, and going up against a car will either hurt you or kill you. That’s simple kinematics, and arrogance and self-righteousness won’t change it.

        1. Ignoring traffic laws while driving a car is bad enough, but at least the car will protect the occupant to some degree.

          This is exactly the sort of comment that makes people hate car drivers. Your entire reasoning for why it’s better for cars to ignore traffic laws than bikes is that in a car the driver will be ok when they get in an accident.

          Really? When a car blasts through a stop sign you’re most worried about whether the driver might get hurt?

          This is exactly the same logic that allows hulking SUV drivers to feel that they can text and drive with impunity. It probably won’t be them getting hurt.

          The fact is that most pedestrian deaths are caused by cars, not bicycles. A bike blowing through a stoplight has very little chance of killing anyone but themselves. It is possible for a bike to kill someone, but it’s much much less likely than the likelihood of a car killing someone. Cars kill people. They are dangerous weapons.

          So the question isn’t “why shouldn’t bikes have to adhere as strictly to the road laws as cars?” It’s “shouldn’t lethal machines known for killing thousands of pedestrians a year be held to stricter laws?”

    2. $150 a year – wow. That would pay for, like, 2 or 3 feet of street to be repaved. Or to have maybe 1/4 inch of highway built.

    3. When bicyclists are paying $150 per year (per bicycle) for registration fees, then they can carp about how cars are getting some kind of free ride.

      As someone else pointed out your road tax doesn’t buy you much if you convert it into territory. It is however supposed to be the amount of wear and tear your vehicle makes on the road infrastructure.

  18. If cyclists are really such a worry to motorists, maybe you should find a cyclist in your area and offer to car pool with them? That way they don’t have to buy a car and you have one less cyclist on the road to worry about. Everyone wins!

  19. – Selfishness. Check.
    – Damage to other peoples property on purpose. Check.
    – Actively putting other peoples lives in danger. Check.
    – As much chance of working in practise as design concepts of clueless atrsy designers. Check.

    Yes, it is almost perfect for making me angry. Just change the purpose to bursting open kittens lungs to include cruelty to animals.

  20. I love you Americans. You’re like the Flann O’Brien characters “who nearly are half people and half bicycles” because they’ve spent so much time riding them.
    But instead you’re inseparably attached to your cars. Them darn commies will have to pry your Chevy Lumina keys out of your cold dead, hands.
    Then the whole syndrome crashes into your insufferable sense of entitlement and suddenly we have a nation of bike-haters, plus a tiny but righteously smug resistance movement.
    Hey look – it’s a person in a car. Or a person on a bicycle. Or a person on the sidewalk. Same person. So why spend billions on an interstate for the first one, actively try to kill the second, and ignore the third (most American roads don’t even have a sidewalk – ask Stephen King how well that works)?
    You should go to Copenhagen, or Amsterdam, or even Paris or London these days. You’d hate it. On second thoughts, don’t. We’d hate your Lincoln Navigator or Dodge Ram too.
    Brilliant hack, though. Useless or not – and doesn’t volume have a significant role to play there? I’d like to try it – it’s a fantastic piece of provocative art. Top work.

    1. Why do all Europeans think it’s ok to lump Americans into one group? Yes, that’s irony.

      I’m no longer surprised when the same people who’d weep tears of blood because of stereotyping of other minorities are happy to accuse “Americans” of generally being assholes.

      I’ve spent time in each of the cities you mentioned. So what?

    2. I get what you’re saying chrism, but the reason most American roads don’t have sidewalks is because most American roads are not in cities, or suburbs. The US has a very low population density, and is not, unlike the countries you mentioned, mostly flat. The average commute is 30 miles. Bicycles are not used because they are not practical for most people. They just don’t work the same here.

  21. It is amazing that some form of airless (thus, un-flattenable) bike tyre hasn’t become dominant yet. The manufacturers are still peddling (pedaling?) ancient tech to us. I want some type of indestructi-bike, now!

  22. Well, I’ll be honest. If a biker came up to me and asked to siphon my car tire, I’d happily just take the emergency air compressor out of my trunk and let them use that for a bit.

    If a biker chose to siphon my tire WITHOUT asking, I’d happily call the cops and ask them to please help the biker out (on his way to jail for messing about with my vehicle without permission). But I would ask the cop to make sure his tire got filled, too.

    I’ve done bike commuting, and I’ve done car commuting. I feel for both communities. But of them, auto drivers are vastly more likely to obey the law. Many bikers bother me for the simple reason that they don’t obey traffic laws, which they are required to do, and which makes them entirely unpredictable and dangerous as a result. Not many motorists actually LIKE hitting bikers, but when you’ve got no idea at all of what one is going to do in any given moment, every time you see one becomes a risky scenario.

    1. I’m not so sure bikers are more likely to break traffic laws. I see car drivers not using their turn signals, running reds, not coming to a full stop at stop signs, making illegal u-turns, changing lanes across a solid line, and speeding all the time.

      This idea is only funny if it’s not actually being used. Low tire pressure in a car is really dangerous. Furthermore, you should never take something from someone else without asking and getting their permission first.

    2. Just to get this out of the way, I agree about cyclists’ obligations under the law, and it’s of course common sense that unpredictability in traffic is dangerous.

      But appealing to the Majesty of the Law as standard to which all should be held, as though that were moral or fair, is a mistake, I think.

      Traffic laws are typically designed around the advantages and limitations of cars. Stop signs get put up at intersections where there are a lot of car accidents, and traffic lights follow if car-based property damage or risk of injury continues. Traffic lights are timed so that car-sized vehicles travelling at car speeds can flow reasonably well together, while reducing the risk of property damage. Talk to a traffic engineer about their motivations for setting up particular intersections or light sequences, and see if they mention bicycles.

      There is an “Idaho stop” law in some jurisdictions that allows bicycles to run stop signs if they can do so safely — this, along with bike lanes which specifically privilege bicycle traffic, is the start of formal (i.e. legal) recognition of the fact that bicycles operate differently in traffic than cars, and you can see the rage that even this simple step has generated.

      I’m a recreational cyclist who lives in a major east-coast US city, and I have a pretty pragmatic approach to the rules of the road. It’s true that I can generally get away with blowing through stop signs and anticipating the occasional green light, but it’s also true that the rules don’t protect me as much as they do cars, because the laws are mostly about property damage (seriously, one measure of the seriousness of an accident is the dollar value of the property damage), and bicycles have low monetary value compared to cars. If someone backs out of their driveway into me, or turns right across my path, and I get hit, the police, whatever their personal sympathies, are unlikely to take official action. Even if I’m injured, the stats affirm that, under the law, it will likely be treated no differently than if I had simply fallen off my bike, and the third party who violated my right of way may not even be mentioned in the report, if indeed a report is even filed. The equivalent car accident would involve greater property damage, insurance claims, and police reports with great care paid to names and addresses of those involved.

      Which is to say, in cartoon form, if the rules of the road do not respect me, then I am less motivated to respect them.

      For clarity, I reiterate my understanding of cyclists’ formal obligations under the law, and the common sensibility of behaving courteously and predictably in traffic.

    3. I have been a bicycle commuter for over ten years and the only accidents I have ever been in resulted from a car breaking the law (usually running a stop sign). These don’t happen very often, however, because I pay a lot of attention to what’s going on around me when I’m biking, and while cars often behave unpredictably and dangerously, I am usually able to react quickly enough to prevent disaster. Cyclists don’t particularly love being hit by cars either.

  23. I know the physics has been thoroughly disputed at this point,
    but I like that people are still saying the volume of the air in the car tire counters the fact that it’s at a lower PSI.

    That’s exactly why I fill my tires using the ambient air in the atmosphere (low PSI, high volume).

    1. That’s exactly why I fill my tires using the ambient air in the atmosphere (low PSI, high volume).

      +1 — Beautiful use of reductio ad absurdum.

  24. there are many practical solutions for fixing a flat tire. This solution is fantastic for fueling conflict, and appears less than helpful for it’s physical function.

  25. With respect to the old “but cyclists break the rules” argument….

    1) Motorists exceed the speed limit for most of the distance they cover. The only thing that stops them breaking the speed limit all the time is other motorists getting in their way.

    2) Most turns and lane changes are not signalled. I mean, with a Starbucks in one hand and their cell-phone in the other, how could they be expected to do this?

    3) Motorists NEVER stop at stop signs unless their advance is directly impeded by other motorists. I mean NEVER. Sure, most slow down to about the speed of a bicycle, but stop? NEVER. You can confirm this by observation.

    1. Yes, it’s utterly amazing how moterists are always spluttering bile at the way that cyclists break the laws, but it’s considered normal in this country (the US) to drive 10-15 miles over the speed limit.

      You should see how drivers rage when stuck behind an old granny driving exactly at the speed limit.

      Oh, speeding on the highway isn’t as important as a bike running a stop sign? Oh wait, it’s just one of the leading causes of death in the US.

      So how about a deal, car drivers: if you’ve never once driven over the speed limit, then feel free to get angry at others breaking road laws. If not, shut up.

      I ride both a bike and a Vespa (and a car when need be, but don’t own one). On both I see cars breaking the law all the time, but the other biggest one, besides the speed limit, I see all the time on the Vespa: Cars really really really really suck at using their turning signals. They really don’t use them. They are so incredibly bad at signaling their turn. On my 50-minute commute to work outside of Boston I count off the idiots who don’t signal — I normally reach 30-40 just on my way in.

      (Ohhh, and this “pump” displays a failure of understanding physics, as others have said.)

      1. (Ohhh, and this “pump” displays a failure of understanding physics, as others have said.)

        Could you kindly explain the physics involved when you connect this between a flat bike tire at 0 psi and a car tire at 30 psi, and the air is pumped into the bike tire?

        1. Air will flow into the bike tyre until they are both at the same pressure. This will be a little less than 30 psi. The amount less is a function of the relative volumes of the bike and car tyres. The way to work it out is to multiply the starting pressure (30) times the volume of the car tyre, then divide this by the total combined volume of the car tyre and bike tyre.

          As always, there are other factors to consider. Temperature effects (adiabatic expansion of the air will cool it) may alter the result and, strictly speaking should be taken into account. I think allowing the temperature to revert to ambient after the transfer is complete eliminates this effect, though. The other factor is the elasticity of the tyres themselves as the volume will slightly change in response to the pressure changes. I think this can be effectively disregarded for tyres as the effect will be small, but it means that trying to model this with balloons, for example, would be fraught. Having said that, the car will squash the tyre down a little as it loses air and this volume change might be more significant. You would get a slightly different (lower) outcome if you stole air from the spare.

          The bottom line is that the maximum pressure is less than 30 psi. This is inadequate for skinny-tyred bikes (close to unrideable) but is fine for a mountain bike.

        2. Is that 0 psia or 0 psig? Are car tyres rated at 30-50 psig? That would make sense, right? Otherwise the extra 14.7 psi for atmospheric pressure means that car tyres run barely above 2-3 atm, which seems rather low.


        3. Could you kindly explain the physics involved when you connect this between a flat bike tire at 0 psi and a car tire at 30 psi, and the air is pumped into the bike tire?

          Sure. In that case, your bike tire would be pumped to 30 psi. Which in terms of bike tires isn’t significantly above flat — it’s very hard to ride on a 30 psi tire.

          I like this as a metaphor, but if you actually wanted to plan in advance for emergency air then you’re much better off buying a tiny pump. Many pumps are the same size as this tube.

      2. Yes, it is motorist who overwhelmingly and repeatedly demonstrate that they are unable to use roads safely. 40,000 deaths per year (and many more times serious injury) in the US alone. We should be outraged.

  26. We in Massachusetts had to pass a law recently to stop drivers from typing on their cell phones while driving. A law.

    Think about that.

  27. It is very frustrating to drive a car because you are in a vehicle that is capable going very fast and shortening your travel time without you having to expend any effort, but then there is all this annoying traffic on the road keeping you from attaining that time saving speed you feel entitled to.

    The most honest example of motorist vs. bicyclist hostility I have experienced was from a woman who honked and gave me the finger because she had to wait a few seconds to make her left turn because I was going straight in the oncoming traffic lane. I wish I could have caught up with her to hear her explanation of what she thought I did wrong.

    Motorists don’t like bicyclists because we slow them down occasionally. It’s as simple at that. Any complaint about breaking traffic laws is a red herring. If motorists really cared about obeying traffic laws they would be driving a lot closer to the speed limit and signaling for every turn.

    The only way to be happy driving a motor vehicle in traffic is to drop the expectation of being able to shorten your travel time by driving faster. Leave sooner or be content to arrive later. Find a good radio station or get books on tape to make your time in the car more enjoyable so you don’t resent every additional second that being slowed down by other traffic adds to your travel time.

    1. Back when I used to drive on country roads with two unmarked lanes people would often pass me as a car was headed towards them in the left lane, narrowly avoiding a collision, because I was only going five miles over the speed limit and they wanted to go fifteen.

      Ten minutes later, I’d pull up to a stoplight and be right behind them. After all their internal calculations (if any) and risk-taking, they actually only succeeded in getting an extra car length of distance.

  28. Even as some leech was bleeding my tire because he was too lazy, cheap or short-sighted to keep a pump handy, I’d have to admire the pure chutzpah of this device’s designer. It’s genuinely subversive, and about as foolproof as you can get. Locking gas caps became the rule when siphoning gas really caught on. But how is anybody going to “lock” the air valve on their tires?

    1. locking valve caps do exist – I think Alligator make thm, for HGV and specialist use. The Germans think of everything…Incidentally, when did siphoning petrol become commonplace? 70’s oil crisis?

  29. ‘course for real villainy, just leave the bike end open. Mmm, flat-u-like.

    77 comments on a Sunday, though? It’s a great troll.

  30. For years, I have had a nearly identical device that a pack-rat friend gave me when I got a new van. It is longer, and it is meant to EQUALIZE pressure between two CAR tires, so that the car could get somewhere safe with a patched tire. I’m sure it was designed before those spray tire inflators (which do work) came on the market. This particular variation on an old invention seems a bit ill conceived. I am just mentioning that it is nothing new, and I don’t imagine the maker of this variation meant it as a ‘parasitic bike pump’. Maybe, but it’s just a strange idea, when high pressure hand pumps are about the size of a banana.

  31. My old man made one of these for sand driving in the deserts of Australia- the trick is you fill your spare with 100psi (can be done safely!) Then you could deflate to float over deep sand and get going again in seconds on hard packed.

    I used an old spare tyre at home for my bike just as above- but yet again, put 100psi in it to make it a worthwhile exercise.

  32. Allrighty, after reading all this speculation about whether or not this device would work, I demand an empirical study.

    Somebody here knows how to get hold of the Mythbusters, right? They should be able to settle this before breakfast.

    Also, as a die-hard pedestrian I hate all of you cyclist and car-owners alike. If the FSM had intended for us to operate vehicles, he wouldnt have given us feet.

  33. Well, I think the whole thing boils down to basic, old-fashioned common courtesy. The motorists get all screechy because they feel like they’re being held-up by a cyclist. Meanwhile, the cyclists feel like they can’t really enjoy a brisk ride without some stodgy motorist splashing their intestines against the pavement.

    If all parties concerned would just have a little common courtesy, understand the situation and proceed with a calm, clear head, there wouldn’t be a problem. Of course, if people were capable of that, we probably wouldn’t need police, a military or psychoactive pharmaceuticals. Still, you get my point. Everybody just needs to calm down and quit acting so savage to each other.

  34. I crack up hearing about the guy who says he has owned several of these and that they actually do have a use. Sounds like survivalist whose trunk is full of MREs and bottled water just in case. Yes, there could be a time when this would come in useful but it takes up about the same amount of room as a bicycle pump so why not just carry something that will be a failsafe backup in all situations. I suspect this was his backup in case his backup pump failed. Me, my backup is relying on fellow human beings for a ride.

  35. This did inspire me to think of other ways that the pressure in car tires could be put to use. For instance I occasionally have a need for compressed air to clean dusty gear, like when I get home from Burning Man. I own a 12V air compressor tire inflator which probably doesn’t give enough flow to really blast the dust off my gear. But using my car tires as a reservoir, perhaps I could get sufficient pressure. Anyone want to try replacing one end of this device with a blow gun and tell me if it works? That’s save the hassle of renting an air compressor

  36. After reading the headline in the latest from boing boing email, I was disappointed to see that it is just a null-air hose. I had hopes that it was a variation of a Skookum Pump that somehow got around the fact that a compressible fluid like air cannot generate a hydraulic hammer effect.

  37. There are different rules (laws) for cars and pedestrians when they are both sharing the road. Pedestrians, for instance, are to use the opposite lane, the one facing the oncoming cars. Also, pedestrians don’t have to stop at a stop sign. Duh, they can walk and chew gum at the same time.

    The point is that it is ridiculous for cars and bikes to share the same laws. The “Idaho Stop” law, mentioned above, where a car stop sign is equivalent to a yield sign for bikes, is a good example of different laws for different realities.

    That logic needs further extending when it comes to creating laws for bikes.

  38. Yeah, looks more to me like a “subversive” objet d’art rather than a tool with much utility. But what the hell.

    I have a device you just don’t see much anymore: a tire pump that screws into a spark plug hole on your (pre-OBDII) engine, and it slowly inflates your tire via engine compression. God only knows what the atomized fuel will do inside your tire, but dating from an era when air compressors were pretty few and far between outside of service stations, it did the job. My dad used it for years before I was born. I used it successfully once, back in the late 80s. About ten years ago, the hose had degraded enough that I kept the valves and fittings and junked the hose, with an eye to replacing the hose sometime later. Still haven’t gotten around to it.

    It’s a neat piece of midcentury toolbox.

  39. People who enjoy getting mad will enjoy getting mad

    Well, if that was your intention in posting this, then mission accomplished–the car/bike debaters are obviously always ready and willing to come to the fore for something like this.

    In terms of something that’s actually useful, not so much. Portable bike pumps abound, and a CO2 cartridge with an adapter is about the size of a cigarette lighter. If someone is too tired to use a hand pump, they’re not going to have much luck trying to find a willing “air donor” or be able to fend off an angry SUV driver who finds them leeching air without their permission. I got a negative impression of Instructables from one of their previous bike projects, one that would replace the front wheel of a bike with a shopping cart–a superficially cute idea with a number of serious practical problems with it, not the least of which is the question of what happens when you hit a pothole with the dinky shopping cart wheels, at speed–and this isn’t helping my opinion of them any, frankly.

  40. Well, I see there’s a great (ie. not so great) discussion of who breaks more laws, so I suppose I might as well chip in a little more.

    As a biker, I did a roughly 5 mile commute. The vast majority of motorists I passed obeyed all traffic rules and were entirely predictable. I similarly obeyed traffic rules, stopping at stop signs, waiting in line on thin roads, etc. The one who didn’t hit me. Similarly, I observed pedestrians generally obeying road-walking rules, and walking against traffic on the road only when a sidewalk wasn’t available, and crossing where appropriate.

    As a driver, I have a rather longer commute. The vast majority of drivers I pass, or who pass me, are obeying the traffic rules. I have something like 2 to 5 near misses with cyclists every day, since they can’t be bothered to wait in line at all-way stops, signal their turns (or, even worse, signal with the wrong arm, using signals they designed themselves), swerving from available bike lanes into the road and back when the bike lane is fully paved, etc. Because so many cyclists behave unpredictably, it is impossible to know if any other cyclist will obey the laws, and so they must all be treated as unpredictable. Pedestrians in this area continue to walk against traffic in non-sidewalk areas for the most part, and to either cross at crosswalks or, at the very least, cross when the road is clear.

    As a pedestrian, I’ve noticed that cars, by and large, give plenty of leeway, while bikers won’t look twice before nearly mowing you down. Similarly, you have no idea when stopping on a sidewalk might get you rammed by a bike, which is legally required to be operated on the road. Similarly, drivers actually stop at lights at cross-walks, giving you time to cross, while bikers just plow right through, moving from ‘driver’ to ‘pedestrian’ at the speed of thought.

    Maybe the laws aren’t designed for bikers. But, in my admittedly limited experience, bikers have far more to answer for than people using alternate means of transportation. And I say that being someone who has operated three modes of transportation, in varying levels of city density, at various points in my life.

  41. Oh man. I have a bike, and a car. I use them both in varying situations, as appropriate. When I’m on one, I’m cautious sharing the road with the other, because hitting or being hit is unpleasant for everyone involved.

    But thanks to the internet, I now realize that the only option remaining to me is to run myself over while rolling through a stop sign so that my purity of essence is not lost! Thanks, internet!

  42. I’m amazed at the number of (professed) bike riders who apparently have never owned or apparently even looked at a mountain/city bike.

    32psi will do you, folks.

    1. Church gets it and SamSam doesn’t – fat-tire bikes run at much lower pressure than skinny-tire racing bikes. Most of the mountain or crossover bikes I’ve used over the years want 50-60psi for street use, and lower pressure for off-road. 30psi is just fine for getting you to the gas station, and while it’s a bit slower than full pressure, it’s a lot faster than carrying your bike.

      Is it enough for a skinny-tire bike? I don’t know; there are enough potholes, curbs, streetcar tracks, wet roads, and such that fatter tires work better, and San Francisco’s hilly enough that mountain-bike gearing is what you want unless you’re a fixie-jock.

      And one of the realities of biking in a big city is that anything even vaguely valuable that you leave on your bike will get stolen. A pump is doomed unless you carry it inside; one of these things tied around the post might still be there at the end of the day.

  43. It hardly matters whether or not it works: as an object, it’s sole function is to be the perfect metaphor for the arrogant sense of entitlement exhibited by your average bicycle commuter.

    Yes we expect to be able to use the road as we have the legal right to, and not be driven off the road by raging d-bags like yourself. Oh and many of us drive cars sometimes as well….imagine that.

  44. I’d hate to see what would happen to the bicyclist caught siphoning air from the truck of one of the teamsters I work with. They’d be lucky to just have their bike run over

    I imagine the cyclist would get a really mean look as your friend decided he better take a long lunch before getting started, then he’d have to gather up a few more fellow workers to sit around and watch the eventual beatdown. Of course by then this person would be long gone……

  45. One major problem with regard to cyclists and following the rules of the road is a lack of education.

    Both on the part of cyclists – too many don’t know the rules to follow them – and on the part of motorists – too many don’t know the rules of the road as they apply to cyclists, and get all freaked out if you do something crazy like signal a lane change, give them lots of time to make sure they’ve seen you signalling, and then move into the correct lane to make a left turn. (Seriously, I’ve had drivers swear at me for this, like I was being upredictable. Of course they may have been on the phone, so their ability to predict was hampered…)

    Everyone who’s on the road in a car should have a license, which should mean that they took driver’s education, and should have learned the rules at least well enough that they could pass a test before forgetting the details. That’s a lot of “should”s, but it’s something.

    There’s nothing like that for cyclists. Sure, there are some cycling courses out there you can sign up for, if there is one in your area, and if you know about it, and if you can afford it (or it’s free), and if you aren’t busy on the evenings when it’s held. Or, you could just go buy a bike and get straight to riding, blissful in your ignorance.

    I’m not proposing that there should be cycling licenses the same as driving licenses (maybe there should, I don’t know – but I’m not proposing it).

    What I would love to see is for cycling courses, including rules of the road and safe cycling, to become mandatory parts of phys ed classes at elementary and high schools. The course should be repeated every couple of years, with a progressive shift toward cycling on the road, right up until phys ed is no longer mandatory. Where I live that’s around the 10th grade, about 15 or 16 years old – right when people start to get their driving licenses – which is ideal, since cycling, and the way cyclists should behave, would be fresh in their minds when they start driving.

    Even if the students don’t ride in traffic ever again, or even never ride a bike again, I think it would improve everyone’s safety immensely – every cyclist would have (the chance to have) learnt the rules of the road, and they’d know that everyone else on the road knows that they ought to know the rules.
    Similarly, every motorist on the road would remember having been a cyclist, and know what cyclists are allowed and expected to do. They’d also remember just how threatening certain motorists’ habits can be, even if they aren’t intended that way.

  46. This could be useful for car owners – filling air mattresses, kid float devices etc. from a spare tire. Also, could a spare tire be safely inflated to 100 – 150 lbs. pressure with a compressor and kept as a reservoir in the trunk? I think so, just have to remember to let a bunch of air out before putting the spare on the car.

  47. Regarding air pumps, I was getting my new bike sorted out at a shop today and noticed the fast CO2 pumps and had an idea: rather than use one-shot cartridges, why not allow them to be pumped up at home with a decent floor pump? The two issues I see here are getting a pump that can handle that kind of pressure, and the temperature rise it would cause.

    And as to traffic laws… I try very hard to be conscientious, despite what some people may think. I listen to the radio/music while cycling, but stay highly aware and paranoid (plus, traffic noise feels different to and is highly distinguishable from earphone music). I will often run red lights, but only if I have made absolutely sure there is no traffic or danger otherwise from doing so.

  48. i’ve been using an almost identical object as an example of a ‘provocative technology’ for the last several years: ‘Leech’ (2005), by Justin Fiske. justin intended it as a commentary on the relationship of car and bicycle riders, from his experiences dodging cabs on his bike in london. this version seems to be doing that provocative job well-ish; though i never would have predicted the amount of vitriol out there over a bit of air. playful, is more the intent, i would think.

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