My (irradiated) balls are always bouncing

A reader writes:

Do you ride motorcycles or know anything about them? Please take a look at the RiderSaverâ„¢ EMF Shielding for Motorcycle Seats.

It's a bit of a long read, and I will not cover my nutts with aluminium foil anyway so you don't need to read it, but in case you do, is there really some bad radiation on motorcycles that could harm my precious balls?


This remarkable item appears to be the product of one Randall Dale Chipkar, who has a Web site for the product and his "Motorcycle Cancer Book" here. And whaddaya know - yet again, here's a proudly-displayed patent for a device, once again exploiting the general public's belief that you can't patent a thing unless it works. (You can actually patent pretty much anything you like, however crazy, as long as it's sufficiently different from other patented things.)

The nutty-sounding stuff on the RiderSaver product page about how the "outstanding magnetic field attenuation results from a unique heating/cooling process within a hydrogen reactive atmosphere" means that RiderSaver EMF Shielding is - or is at least supposed to be - "mu-metal", which is indeed commonly used for magnetic shielding.

There are some problems with using it for this purpose, though.

Problem one: Mu metal doesn't just "soak up" magnetism, like heavy drapes soak up sound. To use mu-metal to "contain" a magnetic field, you have to form the metal into a casing right around the field source. (You can do the same thing with ordinary mild steel, by the way - it just won't work as well.)

Just putting a mu-metal "hat" on top of a field source won't do this, though. It'll do something, but it's quite possible that you'll actually end up with the magnetic field lines being pulled down and concentrated right where your arse meets the seat, which I'm given to understand includes a piece of the anatomy known technically as the Bollockular Region.

(There's more info on all sorts of shielding as it applies to electronics, with helpful diagrams, here.)

Problem two: Mu-metal is for screening low-frequency, or static (i.e. just a permanent magnet) magnetic fields. The higher the frequency at which a field is oscillating, the less effective mu-metal will be.

If you've got a two-cylinder four-stroke motorcycle chugging along at 3000 RPM, its spark-plugs will be firing fifty times per second, giving an electromagnetic field around the plug wires that oscillates at that same 50Hz. And changes shape too, depending on the ignition-system layout.

50Hz isn't high-frequency - it actually qualifies as "extremely low frequency", or ELF, and ELF magnetic fields are what bother a significant portion of the people who're worried about the effects of non-ionising radiation on health. Mu-metal is often used to shield EMR in the 50-60Hz range, which is what you get from mains electricity.

[Although, as commenters point out below, the radio-frequency energy emitted from spark-plugs and their wires is broadband RF noise from DC to daylight, because that's what sparks do.]

The 50-60Hz fields from overhead power lines are a big concern for the EMR-avoiders, though I don't think anybody's ever demonstrated there to be any real risk. Yes, people who live under power lines have a higher incidence of many diseases including cancer. But people who live under power lines also tend to be poorer than people who live somewhere more picturesque, and poor people get many diseases, including cancer, at higher rates than rich people. If you do a proper test that controls for these "confounders", the health "effects" of power lines approach zero.

When you start digging into stuff like this, you'll soon find people using for support reports that say things like "the risk was elevated but not statistically significant". This is an unfortunate choice of words, because to Joe Average it means "the risk was only a bit higher". Statistical significance is actually what tells you if a result is likely to reflect reality, or just be due to chance.

A lot of medical studies use a "confidence interval" of 0.95. If something is statistically significant to this degree, there's only a one in twenty chance that it's just a fluke (and if different 0.95-interval studies all find the same thing, the probability of error drops rapidly).

Something that isn't statistically significant is something that doesn't achieve a decent confidence interval. A measurement with a confidence interval of 0.6, for instance, is only 60% likely to be a real result not due to chance. It's not wise to make decisions based on lousy confidence intervals, and what you should say if you're talking about dubious results like this is "there was no statistically significant difference in risk".

Getting back to engines, it's easy for them to produce magnetic fields at higher frequencies. If you've got a four-cylinder four-stroke bike pushing a bit hard at 8000RPM, for instance, the spark-plug field will now be oscillating 266.7 times per second, and mu-metal shielding will be less effective.

The other significant electromagnetic-radiation source in a bike or car is the alternator, which is all made out of electromagnets (alternators are related to field-coil electric motors, which were the only game in town in the days before good permanent magnets). Half of the electromagnets in an alternator are whizzing round and round; the alternator therefore creates a complicated rapidly-changing high-frequency magnetic field which mu-metal is probably not very good at shielding at all.

Problem three: Mu-metal actually needs to be hydrogen-annealed when it's in its final form. This is part of the reason why mu-metal shielding is expensive; you can't just buy a flat sheet of it and wrap and hammer it around whatever you want to shield. But the Web site for the allegedly-mu-metal stick-on RiderSaver stuff says it "can be cut and is bendable and pliable to accommodate intricate motorcycle seat internal base pans". As soon as you cut or bend mu-metal, you'll work-harden it, and its magnetic permeability, from which comes its high shielding ability, will be decreased. If all you do is wrap mu-metal foil around a box then it'll still work pretty well, only failing on the bent edges, but if you change the shape of most of the surface so you can jam your seat back down on top of it, you may well end up with no better a result than you would have gotten from some cheap sheet steel.

(All modern hard drives have a couple of high-powered rare-earth permanent magnets inside them. There's close to zero field outside or even impinging on the platters right next to the magnets, though, because the magnets are on the inside of an iron pole-piece assembly. Mu-metal would work even better, but it's not needed.)

Problem four: There's not actually any good reason to suppose that any of the clearly-understood risks of sitting on a motorcycle seat, above a spark-ignition engine, have anything to do with magnetic fields or electromagnetic radiation.

Motorbikes are dangerous, but that danger comes from Newtonian, not electromagnetic, physics. (I like the observation that if motorcycles had only just been invented, there's no way they'd be legal.) Per distance travelled, motorcyclists are something in the order of 35 times as likely to die as car drivers. (These numbers are the aggregate for all motorcyclists, though; if you ride a sedate commuter or cruiser bike then you're actually pretty safe. Crotch-rocket sport-bike riders apparently have a death rate ten times that of other motorcyclists, and they affect the statistics accordingly.)

If I had a bike, I'd be focussing my attention more on heavily armoured clothing than on any theoretical danger to my precious bodily fluids from non-ionising radiation. A factory-fitted device that disabled a bike's ignition if it detected that the rider was only wearing jeans and a T-shirt would do quite a bit to reduce bike-related deaths and injuries.

There's no way to convince some people that non-ionising radiation from phones or powerlines or wireless networks or whatever does not seem to be a significant health risk. "It's still radiation, isn't it?", they say. "And I read that Wi-Fi causes autism, too!"

Similar reactions to "nuclear magnetic resonance imaging" are what caused the name to be shortened to just "magnetic resonance imaging", or MRI. MRI machines have nothing to do with nuclear weapons, of course, but "nuclear", just like "radiation", equals "bad" for most people. Explaining that visible light is also a form of radiation doesn't seem to help. It's all forms of non-visible radiation that're considered to be dangerous. (See also people who won't eat food that has "chemicals" in it.)

There's a whole family of bizarre products and books having to do with the terrible dangers allegedly posed by all kinds of invisible radiation, empirical evidence be damned. "Electrosensitivity" - the alleged deleterious effects of non-ionising radiation of one kind or another - is a big market at the moment. Look at those "radiation shield" stickers for cellphones, for instance, which work every bit as well as the "antenna stickers". There are also cellphone anti-radiation products that may actually work; there's just not much reason to suppose that they're necessary.

(L. Ron Hubbard was ahead of the radiation-scare trend, in his inimitable style.)

But there are also plenty of people who believe that static or pulsed magnetic fields are good for you. There's some actual very narrow scientific support for this - pulsed magnetic fields may have some effect on the healing of fractured bones, for instance - but it is largely a crock, about as believable as the old electric belts. (Though presumably less harmful than the old health devices that used ionising radiation.)

Over and over, alleged "electrosensitives" have failed to demonstrate that they can even perceive electromagnetic fields and radiation, much less that those phenomena cause any ill effects. But that doesn't stop them from buying products like the RiderSaver that claim to protect them.

I find the RiderSaver much more amusing than most bogus radiation-blocking doodads. Worrying about whether EMR is in some unknown-to-science way barbecuing your bottom while you ride your donorcycle strikes me as being like making sure you put on extra sunblock before you participate in the Running of the Bulls.

23 Responses to “My (irradiated) balls are always bouncing”

  1. TwoHedWlf Says:

    Ahahaha, worrying about magnetic fields from a bike? That's like a soldier worrying about lead toxicity as someone empties an assault rifle in his direction.

  2. Ziggyinc Says:

    24 years ~170,000 miles (273,000 km) and my son is just about to turn three. I am not worried about what radiation any of my motorcycles are putting out. My wife rides as well, so aparently females are immune also.

  3. mlipphardt Says:

    The actual EMF frequencies will be much higher than the firing freq of the plug since the spark plugs are, umm, spark plugs. Spark gaps are great RF generators, and I imagine the rise time of the voltage spike is pretty damn quick too. Pretty much any frequency you want will be emitted and carried back through the wiring to toast your bollickular(did I get that right?) region.

    Of course since this is not ionizing radiation, the absolute worst it could do is warm said region a little. And I doubt the power levels are high enough to even do that to a measurable degree.

    So screw it. Not worth worrying about. It is proof however that if you use enough scary and confusing words you can sell anything.

  4. MorganGT Says:

    I'm not sure what he thinks the problem is - if riding a motorbike really did something bad like giving you testicular cancer, then you'd lose your balls. And since 'too much balls' is the sort of attitude that tends to get motorbike riders in more trouble (and put them at more risk), it would probably be almost good for your health!
    I know of what I speak, I only just got my licence back after an enforced 12 month holiday from riding due to that sort of behaviour!

  5. carpe_diem Says:

    The III study you quote for motorcycle (specifically crotch-rocket) fatalities has been pointed out as quite flawed by the AMA.

    "In other words," said Moreland, "it's entirely possible this report actually demonstrates that younger, less-experienced riders are more prone to crash than older riders, regardless of the type of bike they're riding. And that's true for all types of motor vehicles--cars, trucks or motorcycles."

    There are numerous other flaws with the study, the lease of which is that the III classified bikes into incorrect categories.

  6. Mohonri Says:

    Drat, mlipphardt beat me to it. The ignition coil and spark plugs create all sorts of noise across a rather large spectrum. That's one of the reasons your car stereo is heavily shielded and has beefy power conditioning on its supply.

  7. Daniel Rutter Says:

    OK, that's fine... but the fact remains that the much higher fatality rate for people riding hot bikes make the whole motorcycle category seem more dangerous than it actually is, for people who decide to ride less alarming bikes. Which is all I was saying.

    Some of the objections raised by the AMA (which, to clarify, is the American Motorcyclist Association, not the American Medical Association :-) also strike me as entirely ridiculous. Are they seriously, for instance, contending that cruiser and commuter bikes are, on the average, driven less far than racing bikes? (I presume not, since in the next breath they're on about how interstate highways are safer than urban roads. Also longer, I think you'll find.)

    Even if by some miracle people really are riding their Hayabusas across America and only taking their Gold Wings out for occasional track days, it still doesn't change the fact that sport-bike riders (along, I would presume, with dirt bikes with knobbly off-road tyres being ridden on the road...) are better represented in the fatality stakes than riders of more sedate motorcycles.

    The AMA has a valid complaint about the weird categorisation system used by the IIHS report, putting the fastest bikes on the road today - including the Hayabusa - in the "sport" rather than "supersport" categories. But I did not use that categorisation, because I'm perfectly happy to draw the line between "sporty powerful bikes" and "everything else".

    The weird categorisation system was apparently cooked up to aid the IIHS in its attempts to ban fast bikes. The ultra-fast bikes actually apparently have a relatively low death rate - presumably because your average 22-year-old freeform-urban-racing enthusiast can't afford them, and older racers take it a bit gingerly, partly out of good sense and partly because they just don't want to lay the bike down and have to pay a small fortune for another fairing. So the IIHS decided to quietly demote the ultra-bikes to mere "sport" status. The AMA is, of course, pissed off about this.

    But the fact remains that most fast motorcycles have, for whatever reason, a much higher rate of deaths-per-vehicle, which skew the statistics for the whole motorcycle world.

  8. Ziggyinc Says:

    Dan, I hate you for pointing that out, but I cannot argue.

  9. Ziggyinc Says:

    I myself berely survided my young motorcycle years, but I still place riding up there with sex on the list of greatest things ever.

  10. Alan Says:

    If you really want to reduce EM radiation, I think you'd have to get rid of the spark plugs.

    Don't diesel engines use glow plugs for cold-weather starting? Offer a motorbike that runs on diesel.

  11. phrantic Says:

    Think of the fuel costs!!

  12. Chazzozz Says:

    *sigh* Yet another example that I'm in completely the wrong job. I wish I could think up something as hilariously almost-believable and use it to part dumb shmucks from their money. A little something called 'morals' stands in my way, though...

  13. MorganGT Says:

    In the world of motorbikes, the 'SuperSport' name tends to be used to describe bikes that are meant to be 'race bikes for the road' - bikes with a good balance of (lots of) power combined with nimble handling and powerful brakes. 'Sport' bikes by comparison can be more powerful, but are usually not the best at cornering, so in a straight out drag a Sport bike might win, but a SuperSport bike will leave it for dead around a circuit. These days some manufacturers are taking the 'Sport' concept of big engine in relatively basic bike to new heights - Yamaha now call some bikes 'Torque Sports', as they have ludicrously big 1.7 litre engines in something that is not well suited to making it around corners fast.
    And there are diesel motorbikes. There is a trailbike based on a Kawasaki chassis that uses a specially developed diesel engine. The original impetus for a diesel bike came from the British Army - since all their other vehicles are diesel powered (tanks, trucks, Land Rovers etc.) it made sense to develop diesel bikes so fuel supply in the field isn't complicated by having to carry small quantities of petrol alongside large quantities of diesel.

  14. Major Malfunction Says:

    If there really is a higher incidence of bollockular cancer in motorcyclists (I didn't bother looking at the site for actual scientific research, because well, frankly, my time is worth more than that), then it's probably related to a similar cause found in a recent study on bicyclists - Sitting on 'em!

    Bicycles don't generate T3H EMR! but share a similarly uncomfortable saddle and riding position as sports motorcycles, and an increased risk of bollockular cancer (oh, not to mention infertility, erectile dysfunction and prostate cancer)... Connection?

    The study even went so far as to recommend that gentlemen bicyclists should adopt the more comfortable lady saddle. (I also wonder why men's bicycles have crossbars, while the lady's have 'S' bars. Surely, men have the most to lose and we have the ergonomics arse-backwards?)

    And also, if you cared to look, you might even find similar results in horsemen.

    The saddle is the common denominator.

    May I suggest, as a solution, an improvement in masculine seating arrangements?

  15. Major Malfunction Says:

    Gah! I've done it again! Forgot to close my brackets. Dan, can you post a quick tutorial for us less html-enabled?

  16. Daniel Rutter Says:

    I have heard tell, from distant lands, of a thing called a "preview button". We don't hold with that sort of nonsense here, of course.

    I must do something about the lame comment interface; just haven't gotten around to it. In the meantime, since this site has pretty low comment traffic, I can just manually fix comments like yours where a small HTML glitch has borked the whole thing.

    If you get your link formatting right in the first place then it'll work just fine (though it will also add a "nofollow" to all links, and entirely remove stuff like images, embeds and so on), but it should still be better than it is.

  17. mlipphardt Says:

    @major, boys bikes have crossbars and girls don't for a very good, if antiquated reason. The crossbar will make your dress ride up.

    Yes, it used to be that women and girls always wore dresses. If you wore a dress and rode a boys bike, your ankles and (gasp) calves might show, leading to Lewd and Lascivious Thoughts. Can't have that. At all.

  18. Major Malfunction Says:

    I'm sorry, Dan. I promise I'll get it right next time! OK? And thanks. :)

    mlipphardt, have you ever landed balls-first on a crossbar?

    The defense rests.

  19. carpe_diem Says:

    "Are they seriously, for instance, contending that cruiser and commuter bikes are, on the average, driven less far than racing bikes? "

    Here in the good ole US of A, I would bet at least 25% of the guys riding "cruisers" (Harley Davidson and the like) are at most putting a thousand miles per year on their bikes.

    You should see the crowds of cruiser guys riding to the local biker bar that is no more than 10 minutes from their house.

    My guess is that youth, experience (lack of), alcohol and lack of motorcycle helmet laws in many states account for the large part of motorcycle deaths in the US.

    My comments are reserved for the US... I know licensing and safety are taken much more seriously in Europe (and maybe Asia and Australia).

  20. RichVR Says:

    Indeed when I rode I was silly and ignorant about the dangers of radiation. Way back in the day I cared more about protecting my skin with leather and my head with a silly bucket. But then the radiation made me go off the high side on a wet road and break my leg.

    Haven't been on a bike since. Must be the radiation damage to my brain.

    Damn you, EMF, damn you!

  21. Changes Says:

    Diesel bikes make a lot of sense for anyone who uses a bike for practical purposes rather than just for breaking every speed limit imaginable on weekends, but try advancing the idea around here and you get ridiculed to hell and back (guess how I know). I'm sad the diesel Kawasaki KLE isn't sold around here, or I'd probably have one (though my ER-6F/Ninja 650R *is* a lot more fun). And no, you can't just get some old bike with a busted engine and replace it with the engine from a diesel pump, or something, because there is a massive (like, mount Everest massive) amount of bureaucracy in your way. *sigh*

    Dan: since we're talking about scams and spark plugs, you might be interested in the Pulstar, an overengineered spark plug that promises very noticeable gains in fuel economy by "burning fuel sooner and more effectively". Apparently the people who make the Pulstar think the engine's existing coils aren't fast enough, so the Pulstar has a capacitor that collects the coil's energy and discharges it at the appropriate moment in an "amazingly quick (two nanoseconds) pulse". How the spark plug manages to figure out the correct moment, we're not told.

  22. Daniel Rutter Says:

    I wrote about the Pulstar plugs here.

  23. Mr. Peepers Says:

    The thing is, that one of your feet sits next to the motorcycle's magneto, which is just inside the side of the engine case, and has a big-freaking-cylinder of a ferrite magnet that spins on the crank. It's only a centimeter or so from your foot.

    Since the magnet sits in the oil bath, it really makes "magnetic drain plugs" somewhat pointless, but that's a whole other scam altogether.

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