Login to VeloClub|Not a member?  Sign up now.
  • Robert Merkel

    Seems to be some unintended deletions from the following sentence:

    That said, it is possible, even if only in theory, to drive the rear wheel using electromagnetism by turning it into either a switched-reluctance motor — the circular equivalent of a magnetically levitated high-speed train.

    Feel free to delete this comment after correction.

  • All the talk these days is of motors, It’s the batteries that limit the thing. The battery in weight at Kg or more to drive this thing for anything more the a minute.

    • James Huang

      That would obviously depend on the level of output, wouldn’t it? The thing is, it’s not terribly difficult to have a bike that weighs less than the UCI-mandated 6.8kg lower limit so there’s often room to spare. Also, keep in mind that while many of the power claims are pretty big (60W in this case), much less than that can still make a difference.

      • Robert Merkel

        In any case, half a dozen 18650 batteries weigh about 300 grams, fit inside the tubes of a bike frame, and would supply > 50 watt/hours. Even allowing for motor inefficiencies (and this motor would likely be rather inefficient given the compromises to hide it) that’s still enough to run it at full power for 30 minutes or so.

    • Dave


      A conventional 55W.hr laptop battery coming in at about 350g could give you roughly 200kJ of energy, which is enough for 33 minutes of operation at 100W.

      100 watts is a pretty significant boost when you’re riding up a grade, and having half an hour of that boost available would easily be overkill for a 45 minute CX race. Even in a long (i.e. 5+ hours) road race that would be quite realistic, if you saved it for just a couple of big attacks and some climbing.

      • Chris

        I wonder what the efficiency of the wheel described above would be. I’m not so sure 100w added to your power output would be just a 100w draw on the battery, surely.

        • Dave

          Yeah, you certainly wouldn’t get great efficiency from a railgun-style wheel.

          My point was more to debunk the view that batteries are the limiting factor even with normal motors.

    • winkybiker

      I though the same thing, but no. The energy density in modern batteries is improving all the time. Easy enough to carry enough Kj for short burst of power when it’s critical in a CX race.

      • I think you’re right Winky, I was thinking of heavier rechargeables. I imagine it’s all liIo & damn the recycling – full speed ahead.

  • jules

    doesn’t need to be in the rear wheel either

    • James Huang

      In theory, no, but given the relatively low magnetic forces in play here (since such a system would still place a priority on relatively low weight), you’d probably want electromagnets in both the chainstays and seatstays to double the applied force.

      • jules

        what about disc brakes? could electromagnetic motor componentry be hidden in disc brake components?

        • James Huang

          In concept it’d be possible but there really isn’t room in there.

          • jules

            what about..? ok that’s enough :)

            • I should have warned James about you Jules…


      • Arfy

        I’m wondering if you can stick a heap of small neodymium magnets around the inside of the tyre, and using the close-coupling of many aero-bike seat tubes to the tyres, have several coils mounted in there, fired one after the other in “mag-lev” fashion? The article makes reference to “frequency of the applied current”, but this doesn’t correlate. Brushless DC motors are capable of several thousand RPM, and we’re talking a bike wheel with a RPM in the hundreds.

        • Dave

          The air gap (air + tyre gap) would be too great for that.

          • Arfy

            Possibly, but mine’s about 7 or 8mm (between the inside of the tyre and the inside of the seat tube). This is much less than the gap between the rim and stays. Plus you have a tube length of about 150mm that maintains this gap, so you could put multiple large coils (the more windings the higher the magnetic field strength) in there. I think the big challenge would be inserting the magnets in the correct orientation in a reliable way, but I’m sure someone would be able to work that out.

            • Dave

              Unless you’re planning to put the magnets inside the tyre, there’s then another 30-35mm before you get into the hollow section of the wheel rim in addition to the tyre-frame gap.

              Better to go with the coils in the stays, but increase the number of windings, increase the current and use big wide “aero profile” stays (i.e. for a longer cross-section in the direction instead of skinny ones. Best to work with quantities that are directly proportional, not proportional to the negative square.

              Unfortunately Mythbusters has finished. Perhaps GCN could give it a go?

        • The Rabbit
    • Dave

      You wouldn’t want to put the wheel back in the wrong way around after a puncture though.

      • asbjorjo

        Hard to achieve with a rear wheel. ;-)

  • claude cat

    I think the airgap between the chainstays or seatstays & the magnetics in the wheel would be a massive limiting factor.
    Unless you can that very low, the efficiency would be horrendous.

    • James Huang

      Agreed, the scenario seems awfully unlikely for a lot of reasons. Sadly, though, I don’t rule much out these days.

      • claude cat

        And it would be kind of obvious. Why would you intentionally design a road bike to have such minimal clearances other than for this purpose.

    • Dave

      I agree, with current technology the ‘railgun’ approach would be near enough to impossible to implement to a level that would actually be useful on a bike, certainly not while still concealing it well enough to pass even the most cursory inspection.

      • Carol Adkins

        ?my neighbor’ s mate Is getting 98$. HOURLY. on the internet?….A few days ago new McLaren F1 subsequent after earning 18,512$,,,this was my previous month’s paycheck ,and-a little over, 17k$ Last month ..3-5 h/r of work a day ..with extra open doors & weekly. paychecks.. it’s realy the easiest work I have ever Do.. I Joined This 7 months ago and now making over 87$, p/h.Learn More right Here:a260????? http://GlobalSuperEmploymentVacanciesReportsClowd/GetPaid/98$hourly…. .?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?::::a260…..

      • Anna Irvine

        ?my neighbor’ s mate Is getting 98$. HOURLY. on the internet?….A few Town ago new McLaren F1 subsequent after earning 18,512$,,,this was my previous month’s paycheck ,and-a little over, 17k$ Last month ..3-5 h/r of work a Town ..with extra open doors & weekly. paychecks.. it’s realy the easiest work I have ever Do.. I Joined This 7 months ago and now making over 87$, p/h.Learn More right Here:a497????? http://GlobalSuperEmploymentVacanciesReportsFinal/GetPaid/98$hourly…. .?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?::::a497…..

  • Nitro

    Interesting article – shows that there are a lot of things that are theoretically possible…

    I know an Uncle who has had 2 x (Titanium) hip replacements.

    He claims that that’s what sets of metal detectors at airports.

    If he starts appearing at the front of weekend races I’m going to want to see the x-rays to see for myself that there aren’t electric motors hidden in there somewhere…

    • Arfy

      You’ll know when he gets off his bike, accidentally hits the “start” button and his legs start going at 100RPM. Wonder if you can do that with a pacemaker, just turn it up to a higher heart-rate for the final sprint?

      • Dave

        I’d go with a massive electromagnet suspended above the podium. Detection and public humiliation all in the same motion.

        • Arfy

          Love it! Except for the poor guy with the titanium plate in his head …

          • Dave

            I thought of that already – titanium is not magnetic!

            Therefore it can’t be used to make a motor.

  • Robert Merkel

    The question I’d have about this is the economics of this kind of cheating.

    I’m not surprised by the claimed cost of the wheel setup, given the complexity of the engineering and the limited market (there’s no conceivable market for these other than cheaters).

    However, the cost is going to put it out of reach of many who might be tempted, and it’s not that easy to hide a transaction of that magnitude from the police should they develop an interest.

    Not to mention that while this configuration might reduce the heat from the motor a little, the electromagnetic field and waste heat from the coils and the batteries would presumably still be detectable.

    • Dave

      Given that the UCI appears to have settled on detecting motors by their magnets rather than heat signature, this method would be a step back in making it easier to detect, not harder.

      Even the heat signature might not be any lower, depending on what ventilation is available to coils of wire embedded in the surface of the frame.

      When considering how seriously to take this, consider that it was first published by La Gazzetta dello Sport and then on CyclingNews.com – i.e. not very seriously.

    • Larry @CycleItalia

      Dunno about the economics argument in a world where people will spend thousands on EPO in order to win a salami at their local Gran Fondo.

      • Chuck6421

        And more legitimately, what’s the ROI on thousands of hours wind tunnel testing?

  • Grejsdal


  • The Rabbit
  • Steel

    Interesting article.

    This set up is seemingly just as detectable as the seat tube, BB motor. While its unfortunate that technical inspections will now require checks for motor doping, I think a quick bomb with a lixi profiler is going to reveal the innards of carbon wheels/seat posts, stays etc… The chances of detection seem pretty good.


    Why son’t they simply X-ray the bikes. They could use a similar set up to the portable customs X-ray vehicles. It would take seconds per bike and you couldn’t get away with anything at all, ever.

    • Dave

      Do you know how complex and expensive X-Ray machines are?

      Much easier to just use a hand-held device for magnetic field detection, and then open up the bikes which turn up a tentative positive.


        No, not really, but a quick google suggests that they are not outlandishly extortionate. Furthermore considering their extensive commercial use for identifying different types of mass, and the minimum wage workers that often operate them, I suspect they are not particularly complicated. My point is it would be a veritable “one inch punch” for any kind of bicycle pop swankery, electric motors with a magnetic field today. What’s next? Besides, “much easier” is hardly a progressive paradigm.

  • ebbe

    Hey Cyclingtips, If you have somebody on your staff that speaks Dutch and want to have a laugh… Here’s a complete non-explanation from an “expert”, who obviously does not have an engineering background ;-) http://nos.nl/artikel/2084565-ook-met-magneetjes-kun-je-stiekem-harder-fietsen.html

    • Dave

      Even the Google Translate version is hilarious!

      • ebbe

        And the worst is: This is a very serious news outlet.

  • Larry @CycleItalia

    If I was the king of cycling there would be NO batteries! NONE. No electronic shifting, power meters, radio/earpieces, not even a simple cyclocomputer. All the effort, including brain power should come from one source – the rider.

    • Dave

      No components produced using any process reliant upon electricity should be allowed either.

    • ebbe

      I tend to agree, in fact that’s half the reason my new bike has no Campa EPS: I’ll operate my bike with my own hands and feet, thank you very much… but I would allow computers, power meters, radio and lights, since they do nothing to assist in “operating” the bike, but do increase knowledge and safety. And their batteries are not powerful enough to help anybody “cheat” anyway.

  • ummm…

    they were doing the electromagnetic stuff back in the 90s. So passe. Currently there is a form of cheating that has not even been mentioned. I wont be the one to let the cat out of the bag tho.

    • Robert Merkel

      C’mon, don’t leave us in suspense! Is it:

      * invisible tow ropes?
      * invisible aerodynamic fairings?
      * helium balloons under jerseys?
      * getting your identical twin to do part of the race for you? (actually, this is not totally fanciful given the success of the Yates brothers).
      * implanting motors in a rider’s legs?

      Inquiring minds want to know!

      • ummm…

        all very good guesses. although you cant really expect me to divulge; omerta ya know.

        • Robert Merkel

          Actually, I’ve thought of another one that’s not quite as silly. There’s a lot of potential energy in a co2 cartridge. Using a bigger cylinder of something like liquid nitrogen. No more magnetic signature (though of course noise and condensation would be a problem).

          • ummm…

            lol…you may have a job as a team training coordinator!!!!

      • Jim

        invisible car ??

      • ebbe

        Are team cars and motards checked for massively strong electro magnets? No, they’re not!
        Do most bikes have added weight (to get to 6,8kg) by means of metal inserts inside the frame? Yes they do!

        1 + 1 = … ;-)

  • ummm…

    they were doing the electromagnetic stuff back in the 90s. So passe. Currently there is a form of cheating that has not even been mentioned. I wont be the one to let the cat out of the bag tho.

  • Andy B

    I guess the other big advantage of this type of “doping” is that testing retrospectively is very difficult..
    i.e if it wasn’t picked up on the day and is down to rumours it would be very difficult to prove

  • Marc Duchesne

    Keep in mind that most of the bikes manufacturers are pushing hard on the all-integrated designs. Hence, it’s very easy for them to conceal some fancy gadgets inside the frames. See integrated sensors to begin with. Also, look at this new trend with caps : a cap on the head tube, a cap on the seat post, a cap beside the bottom bracket, and so on…

  • Henry R. Remolado

    Procedure in administrative proceedings “FRAME DOCUMENTS” and Commoness.
    ADVOCATE My NIPKOW Disk Machine.

  • Augsburg57

    It has already been proven definitively (with down tube and seat tube motor designs) that significant battery power can be stowed on the bike. So why would it be a question for the wheel motor?

    If I was to approach the problem of hiding a motor on a bike, I’d look at locating super strong magnets on the seat stay or chain stay, or both. I bought some super strong magnets off Amazon for a household purpose and could not believe how strong they can be these days. Anyway, with magnets on the stays, then wire “coils” on the rim offer substantial torque due to the “lever arm” distance of the wheel rim to the axel. Batteries can be in the wheel rim too – like the recent 60 Minutes show implied. The motor could be controlled with bluetooth – so no need for wires. Re-gen to charge the batteries on long downhill descents may even be possible, to extend the life of the battery power.


Pin It on Pinterest

May 28, 2017
May 27, 2017
May 26, 2017
May 25, 2017