Guest Article: An Electrifying Commute, by Jim Tolar

Last week, I began riding my new commute bike, a GT Transeo, to work. My new bike allows me to get off the streets with their heavy traffic, and onto the local canal system, which is almost unused. My route to work is along the canal bank on the irrigation canal that runs E-W, between Elliot and Guadalupe, in Mesa, Arizona. I ride almost 4 miles on the canal before I cut South to Elliot for the final mile or so on the road. The canal portion is traffic-free, quiet, and quite pleasant except for one annoying phenomenon. As I ride to and from work I get occasional, fairly sharp electrical shocks, normally to one of my legs at the inside of the thigh, just below my shorts (sometimes the left leg, sometimes the right, sometimes one then soon after, the other). These shocks are sharp enough that the first few times it happened, I thought a bee had stung me, or that I had jabbed a bare bike cable end into my thigh. This happens at least once or twice on each ride, and has had me groping for some kind of explanation. No bees, no bare cable ends, no debris being kicked up by my tires and hitting me in the legs, no residual marks to indicate injury. A couple of times, I’ve reached down right after this has happened and felt an electrical shock to my finger or hand.

This has happened frequently enough that I am certain it’s not my imagination. After a week of this, I finally figured out what was going on. It’s a practical demonstration of the physical laws that govern many of the machines we take for granted around us.

My route on the canal banks runs parallel to, and about 50 feet directly under, the high-voltage transmission lines that share the right-of-way with the canal and distribute power throughout much of the East Valley in Phoenix. These lines produce a sizable electro-magnetic field (EMF), which is one of the reasons they’re in this right-of-way to begin with. It is well known that a conductor moving through an electric field will generate an induced electric current. This is one of the operating principles behind power transformers, motors, and generators.

My bike frame, as it moves through the EMF generated by the power lines, has an induced electric current (stored in the “loop” that the frame makes). The frame is isolated from earth ground by the tires. It is also isolated from me by the rubber-covered pedals, my running shoe soles, the rubber handlebar grips, and the insulated seat. As I move down the canal, a potential difference gradually builds up between me and the frame. The magnitude of the potential diffeence is a function of speed through the field, the strength of the EMF of the lines, and a secondary function of the humidity (high humidity allows charge to leak away more easily). As the potential builds, eventually some body part (usually the inside of one of my legs) gets close enough to some pointy part of the frame, like a nut or something on the down-tube (static field energy dissipates over long, smooth surfaces, and can concentrate at sharp points) , and ZAP! A shock jumps and equalizes the bike frame and me.

So, in order to prevent this phenomenon, I need to make sure that my body and my bike frame keep at the same potential while riding through the EMF. If I do so, no shocks should occur. I can do that by making sure some part of my body has direct contact with the frame always, or at least frequently enough to keep the potential difference less than the “jump” energy. To test this, this morning on the way in I rode with my thumb off the rubber handlebar grip and resting on the handlebar itself. Nary a shock, for the first time in 5 days.

It also turns out that if I simply ride on the side of the canal opposite the power lines, that added distance is enough to reduce the potential difference build-up to the point where the invisible bees that have been plaguing my otherwise enjoyable commute have gone in search of other victims.

24 Comments

  1. Moe April 9, 2008 9:46 am 

    Dude, that’s crazy!!! I guess you have a good ‘reason’ to upgrade to a Carbon Fiber bike!

  2. Apertome April 9, 2008 9:51 am 

    That’s disturbing. Even though you seem to have found a solution, somehow the idea of riding in a big EMF for an extended time would bother me. Maybe that’s why nobody uses those canals …

    So with your new method, when you get off the bike and touch something else do you get a shock?

  3. RL Policar April 9, 2008 9:52 am 

    Or he can get a wooden bike…

  4. Quinn April 9, 2008 9:52 am 

    No wonder the canal is hardly used! Although IM one of those people that would see the power lines and figure “Discharge, Duh” and then if I didn’t know how to fix it, I would take time to figure it out.

  5. cafn8 April 9, 2008 10:01 am 

    Huh. So finally the the real reason for all those gripless fixies.

  6. Ghost Rider April 9, 2008 11:10 am 

    What a weird phenonmenon!

    You should try cycling with a 48″ fluorescent tube sometime to see if it lights up — I’ve seen someone walk into a power-generating station and the bulb just lit up due to all the “loose” electricity in the air!

  7. Ben C April 9, 2008 11:37 am 

    Just wire yourself to the bike just like computer repair guys. At least you didn’t get shock in your crotch. That may do some damage! OUCH!!

  8. Tim April 9, 2008 12:49 pm 

    Amazing! Staying in contact with your bike is one solution, and grounding the bike frame is another, maybe better, solution. You could drag a grounding strip of some sort to bleed the static charge from the frame. Try an old piece of brake cable clamped in the rear quick-release skewer at one end and dragging on the ground at the other end. Many heavy vehicles have this kind of arrangement to avoid a charge buildup. Some of them, like fuel tankers, even drag a big chain to absolutely minimize the risk of electrostatic discharge.
    -Tim (aspiring Ph.D.)

  9. miker April 9, 2008 2:07 pm 

    I used to experience that along Virginia’s W&OD trail in Falls Church. The trail is also along a power right-of-way & only in the Falls Church section was the power high enough or the lines close enough to cause that effect.

    I used to play with watching the sparks fly between my fingers hovering close to the brake levers (with my hands on the rubber grips).

    Interesting science experiment, but yes, what does that high voltage do to your body systems in general?

  10. Bill April 9, 2008 4:54 pm 

    Ben C has the right idea. If you get an anti-static wrist strap used for computer repair, that should keep the potential energy balanced quite nicely.

    Just watch that first step off of the bike. 😛

  11. Rick April 9, 2008 5:36 pm 

    I remember riding under those types of power lines. There was a constant crackling. I always assumed that there was some sort of charge in the air.

  12. Dartanyon April 11, 2008 10:47 am 

    Have you given any thought to grounding the frame? Just drop a piece of conductive wire off the bottom bracket to the ground, just barley long enough to make sure that it makes contact most of the time?

  13. Jot April 28, 2008 8:41 pm 

    The solution to this is obvious. You have a metal bike, and you need something that can connect you to that. Cut a hole in the front of your bike shorts, and voila, you’re set!

    Probably solves the problem of the extra charge you generate between you and your chamois.

    I’m just saying… :)

    -Jot

  14. Margaret July 6, 2008 7:26 am 

    I have experienced something similar in SW Chicago suburbs, when I ride on a paved bike trail through Cook County Forest Preserves. About a mile of the trail goes under and along high voltage lines that constantly hum and crackle. I usually keep my fingers hovering over brake handles, and if I touch the handles when crossing under the lines, I get shocks in my fingers. Otherwise, it is a beautiful ride! (Just did a Google search to see for the phenomenon and found your article.)

  15. Margaret July 6, 2008 7:28 am 

    Correction – Did a Google search to “check” for the phenomenon and found your article. Maybe those shocks hit my head….

  16. rick July 6, 2008 10:12 pm 

    wow, thanks for that thorough explanation. i had the same exact thing happen to me today for the first time. i was driving along some powerlines when all of a sudden i felt like a hundred tiny “stings” on the inside of my thighs. i immediately jumped off my bike and started to look for ants, bees, etc. to no avail. when i realized that bugs weren’t the cause of my problem, i touched the seatpost and seatpost clamp and immediately felt a tiny jolt, even seeing tiny sparks as i ran my finger along the seatpost. even though i knew nothing of EMF or EMR, i knew that obviously it had something to do with the powerlines and touching any metal parts on my bike. i simply lifted of my seat and made sure to avoid touching any metal parts on my bike as i traveled half a mile or so.

  17. JB January 24, 2009 9:07 am 

    Interesting but I doubt the accuracy of your explanation. To induce a voltage, part of your bike frame would have to be CROSSING the magnetic field lines. To do that, you would have to be moving towards or away from the power lines; you were travelling parallel to them, which would induce no voltage at all. I would suggest that it is more likely that static is being generated, possibly due to the combination of clothing you are wearing.

    You may protest that the phenomina only occurs as you cycle beneath the power lines, therefore it must be caused by them. However, this is probably a coincidence and it is likely that the sparks only occur there because it is a long, flat, obstacle-free part of your ride meaning that you don’t change gear or brake during that part of the ride. Changing gear or braking would necessitate contact with metal parts of the bike, neutralising any static that had built up.

    If, whilst riding beside the canal you do not change gear or brake, sufficient charge could build up to cause a spark to jump. On other parts of your commute, where you change gear and brake frequently, only small amounts of charge will accumulate and no sparks will jump.

  18. Belinda June 7, 2009 10:25 pm 

    The same thing happened to me today when I was riding along the power line route from Higley to Gilbert. The jolts were painful and unrelenting while I was under the lines. My family thought I was crazy, as no one else experienced it. My daughter even teased me that I was probably going to look it up on the internet when I got home. I’m glad I did! I think I’ll steer clear of the power lines, though, as I hate electric shocks — even thinking about it makes my hair stand on end. PS – Why did I experience it and no one else did?

  19. BlackBear June 8, 2009 8:37 am 

    Are you the only one on a steel bike?

  20. Jim April 20, 2010 3:44 pm 

    Belinda,
    I experienced the EXACT same thing as you did. Was dumfounded with what was happening, but after a few trips through the area and actual “sparks” occurring between my hand and the handlebars I finally figured it out. Some days are worst than others, but I finally gave up riding the route after a couple of extremely painful shocks.

    To JB who thinks it has nothing to do with the power lines — you have no idea what you are talking about. It has everything to do with them. I have asked other riders if they have experienced it and a great number of them have. (but not all) Funny I had the same reaction and “googled” it and ended up here.

  21. JB August 27, 2010 12:04 pm 

    Hi Jim,
    If you read carefully what I have written and cross reference it with any reputable physics text, you will find that my comments are in line with scientists’ understanding of electromagnetic induction.
    There are other mistakes in the article too, as it happens – the idea of an induced current being stored in the ‘loop’ of the frame, for example (charge can be stored, but not current, which is a dynamic quantity defined as the rate of FLOW of charge).
    I could go on but I suspect that you’re not interested in understanding these phenomena; I was hoping someone with a grasp of physics would reply to my post. Not to worry; I’ll go away and leave you with your pseudo-science and half-truths to enjoy.
    JB

  22. John October 26, 2011 6:47 pm 

    Hi, we experienced the same thing here in Irving Texas and the power lines that run along the portion of the trail we were on , Campion, look just like the picture. The first time we rode the route it was raining and no one got shocked. The second time we rode my wife thought she was being bitten by ants on her inner thighs. When I tried to hold her bike frame I got a continual shock. As we returned she kept getting shocks and so did I when my hand slipped off my hand grips and onto the metal of the handle bars.

Leave a comment

Your email address will not be published. Required fields are marked *