Friday, August 28, 2009

43 The "Dominant Left Theory" In Bicycling Crashes

This blog brings you new perspectives and interesting ideas in cycling, without any charge. You may pay me back through your continued interest.

Some months back while visiting a good friend of mine, I happened to grab a vintage cycling book off his shelf and flip across its pages. I like the smell of old books. Its like battery acid for the mind of a book enthusiast, just stimulating. In one of its uneventful pages simply titled Appendix, I came across the following words. Read carefully, as the author comes across as completely assured of what he's about to theorize. I'll tell you who wrote this at the end of the quote.

"If you been riding long enough to have some falls, I'll bet that almost every injury has been on the left side of your body. How do I know this? Because its the same for me and many other riders. If you want to find an old bike racer, look for a guy with scars on his left elbow. There seems to be a physiological reason for this and it is very interesting, though it hasn't been formally documented as far as I know. It has to do with the location of the heart, the body's primary organ.

As we know, the heart is to the left of the center in the chest. When the body loses equilibrium, it has a strong tendency to fall toward the heart side. This also explains why most riders find it easier to corner to the left than to the right. And it's why track races go counterclockwise so that all turning is to the left. The reason it feels more natural is that the distance from the heart to the ground is less when turning left than when turning right. Even though track riders often do fall on their right side, this doesn't disprove the theory. It just points out the bike's tendency to slide down the banking.

Cozy Beehive edition of original illustration by Grid Designs

What is the practical value of all this? For one thing it means you may need more practice cornering to the right before it feels as natural as cornering to the left. It may also be wise to wear a protective pad on your left elbow in criteriums, especially if you've injured it before. Should you crash there is a better than even chance you'll land on it again. Keep this "left side" theory in mind and you may find other ways to use it for your benefit. "

The author of those words, documented in the 1985 classic Bicycle Road Racing, was none other than the Polish coach, Eddie B (also known as the father of modern American cycling). Being one of the most respected coaches in history, you'd think he'd make sense with his ideas.

This one is particularly interesting as he's stating that "almost every" injury is to the left side of the body because the body (if you consider it to be an inverted pendulum while on a bike) has a directional falling bias. It is also stated that because this "falling" is easier to the left than the right, cornering towards the left side is as well. Therefore, velodromes are run anticlockwise.

Today, you readers can be fellow mythbusters. I did my part, analyzing some 10-15 real world videos of bicycle crashes. I found no correlations with the statement above and all crashes highly depended on riding conditions. I also counted all my scars and there are more to the right side than the left. I don't believe gravity has a preference for this side or that side.....unless you can take a fresh cadaver, cut the flesh into two equal halves and find out that one side weighs more than the other. Are any of you active in criminal investigations? This whole thing begs me to ask : what side is a dead body more likely to fall towards? (If you have murdered someone, are in jail and use an iPhone to read my blog, let me know....)

So today's question : Is there biologically any reason behind the supposed tendencies to fall towards the left side, or is it just a subconscious reflex action to protect your derailleur and chainring from getting damaged? Ah. Think about that one for the weekend.


We Might As Well Crash

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  1. This is motivating me to go out there on the track and analyze my energy expenditure riding both ways. If one direction is more difficult than the other, it might also mean I'm consuming more energy to do it.

  2. Anonymous1:36 AM

    Good question! I think most of us are right dominated. We can unclip our right legs off from the pedal more easily in perceived danger, atleast I can. Perhaps the un-weighing of the right pedal has something to do with shifting equilibrium towards the left.

  3. Hmmm. Normal riding I am more comfortable turning left. On US roads you usually get a wider radius.

    At race speed I always felt better going right. Probably because most the races I did the most (Wells Ave, dozens of times, and others) all went clockwise.

  4. Smells like total BS to me. I don't any logical reason why this would be true nor any shred of evidence to back up the "theory". Which side you crash on is highly dependent upon the conditions at the time of the crash. Since track riders are always turning left, there is probably a higher percentage of left side crashes on the track.

  5. I agree that handedness/footedness needs to be addressed. I feel like more people are right-dominant, as the second commenter mentions. It might be the ability to keep from falling right as he/she suggests, but it might be more primal than that. It's possible that evolutionarily, we're wired to protect our dominant side as much as possible. I'd guess that a caveman who had to throw a spear wrong-handed was less likely to survive than one who injured their other side in a fall.

  6. Then there is always the fall back of the Coriolis effect. :) Maybe the author has a northern hemisphere bias in his experience. What about riders in Brazil, Australia, etc? Do they tend to fall right?

  7. Anonymous10:13 AM

    what about the drivetrain of the bike being on the right side? how does that affect balance and/or turning?

    I think the talk of clipping out is baloney. I am right-handed but I clip out with my left foot. When I played soccer as a kid I used to kick with my left foot too. It's what feels natural.

  8. I agree with Anon above. This sure smells like baloney.

  9. What about the fact that roads are crowned? That would mean that old american and european bike racers would have scars on their left - but old british/australian/japanese riders would have scars on their *right*.

  10. Eddie B was not the only author of that book. Ed Pavelka was the co-author. Any way to find out who exactly gave the theory?

  11. At the moment the ring finger on my left hand has been injured in a fall three weeks ago and my left leg has more cuts and scars that I can count.

  12. I don't know if there is a science behind this but to me, it sort of makes sense. The heart is the hub of blood pumping so if its beating fast and is offcenter to the body, seems to me like more weight of blood is concentrated on the left side. Don't hold me responsible for that.

  13. Phil - If Pavelka wrote it, surely Eddie came across the statement and stamped an approval on it. He was the main author.

  14. Most of my scars on on the right side.

  15. Hmm, if memory serves me, I've crashed way more times on the left than right. However, the second worse crash ever happened on my right side. I cut up my head something fierce. I've tried it both ways, and I don't like either of them. I met Eddie B. in the 80s. He was pretty opinionated.

  16. Yes, but what about all the right-handed, right dominant people that still unclip their left foot...and let me tell you, I ride with a LOT of them. They think I'm the weird one and have even asked me if I'm "left handed" since I unclip with my right foot... what?! lol

    My recent crash as well as my early crash in the beginning days of learning to clip in/unclip were on the left. PS... even when turning RIGHT. :)

    Thanks for the post cozy...I've been watching for it!

  17. PS.. On a different note, I do NOT find it easier to corner to the left :)

  18. I don't know about the heart theory. I had a collision a month ago and damaged my right shoulder because I was turning away from the impact. On top of that I am right handed and unclip my left foot. Personally I think I am more comfortable on hard left turns cycling (and skiing) because I am right dominant. Perhaps its having my better hand/foot on the outside as I lean inside a turn.

  19. Thanks for sharing this incredible piece of BS. One could just as easily argue that we prefer to fall to the *right*, in order to better protect the heart. The truth is that a cyclist (or anyone else, for that matter,) is
    not conscious of the heart as a critical organ unless it is giving trouble.

    Have you ever been told that you should elevate an injured body part above the heart? Another piece of crap, distributed even by doctors and nurses. As a mechanical engineer, I know the circulatory system is a closed
    loop--blood will flow around this loop whether you are standing up, hanging up-side-down, or floating in zero gravity in space.

    I personally think we fall to the left to protect the right middle finger, which is frequently needed as a signaling device during moments of stress.

  20. Alejandro5:24 PM

    If the "greatest cycling coach" can write nonsense like this, what about the lesser ones. This is one reason I don't buy guru books off the shelf.

  21. First thing I thought when I read this, "He's got his cart before the horse". The reason most falls are to the left is because most turns are to the left. There's nothing really physiological about it. Unless it's a handedness issue. Look at every major racing event (non bike related) turns are traditionally to the left. But to attribute this to heart offset? No. You find just as much organ tissue offset to the right as to the left.

  22. Anonymous9:11 PM

    i took a poll and most riders in the states fall more regularly to the right. where most eastern europeans fall more to the left.

    i can theorize that this is to counter balance the worlds energy and our natural tendencies to fall.

    its true i have way more old and new scars on my right side.

  23. Oilcan : Thank you for the comment, and like all others, is interesting. May I ask if you can link to this "poll" you took? As part of what program was this poll?

  24. @ Heltones, 9:34 am :

    You said : Then there is always the fall back of the Coriolis effect. :) Maybe the author has a northern hemisphere bias in his experience. What about riders in Brazil, Australia, etc? Do they tend to fall right?

    You see, the Coriolis effect would make sense for something traveling at large velocities. The Coriolis Force equation is :

    Fc = -2mω X Vr


    Fc = Coriolis force
    m = object's mass
    ω = Earth's angular velocity (of spin)
    X = vectorial product
    Vr = object's velocity

    As you see, the force would have a very tiny effect on a cyclist traveling at 20 mph. Do it for a bullet, a missile or an warplane and you come up with something measurable. I can't believe that this effect has a measurable role to play, atleast I can find no documented cases of such "falling bias" between northern and southern hemispheres due to the Coriolis. Feel free to correct me.

  25. I'm left-handed, kick with my left foot, jump off with my left foot, smell better with my left nostril (crazy but true), see better with my left eye (even crazier but true), and hear better with my left ear... And always seem to instinctively twist my body around when I fall, so that I fall on my RIGHT side.

    I have a theory that it's a subconscious reaction that my body has to protect my 'good' (i.e., left) side from injury.

    Needless to say, most of my major scars are on the right side of my body, because of this.

  26. Hey Ron, thanks for adding the technical merit to my joking about the Coriolis effect.

    Sorry if the snarkiness wasn't obvious. Clearly, I was wrong with the Coriolis comment and should have suggested it's a consequence of the right-handed spiral of our DNA. :)

    Btw, I love the blog and the engineering perspective on things.

  27. @Heltones : Ha, I'm containing much sarcasm and laughter about this topic as a whole, just to discuss if its true or not. See Leo's comment above for the funny :

    I personally think we fall to the left to protect the right middle finger, which is frequently needed as a signaling device during moments of stress.

  28. From both riding and martial arts experience, I have to support the "protect the dominant right side" theory. My first instinct is always to face my left side to danger.

  29. Most of my scars happen to be on the left side. I always attributed this to the fact that all crit courses that I've raced on turn counterclockwise (probably to keep consistent with velodromes?). Most of my crashes that warrant scars have been on crit corners. I live in Australia BTW.

    When I lived in Canada I was more into mountain biking. However most of my falls were still on the left. I always tried to fall on the left if I ever had a choice about it because it could potentially save my derailleur.

    Great post Ron. I'm continuously impressed by the interesting material you come up with!

  30. Anonymous4:26 PM

    Didn't Eddie B also say cyclists should not drink much water on the bike? Great coaches don't necessarily have to be rational in every thing.

  31. I just found your blog. As a 4th year mech E student I really enjoy your perspective and writing style. Keep it up!

  32. Thank you Crispy and welcome. You can find me in facebook and become a fan of the site as well. Keep reading.

  33. Long before I began riding bikes, I rode a skateboard or a snowboard every day of my life. I am goofy footed (right foot forward)and have a tendency to fall to my right side no matter if I am riding a bike, a skateboard, or am just running down a trail.

    If you watch a cyclist coast down a steep hill, look at which foot he puts forward when he stands on the pedals and I guarantee that most of his scars will also be on the same side of his body.

  34. Might as well jump on the bandwagon and join in calling bullshit.

    There is no way the offset of the heart is going to have any effect. Its not that big or heavy of a part of your body.

    Most people have significant side dominance related musculature differences (bigger, more muscled arms, shoulders and legs) and those weight differences are going to be at least as significant (if the are significant at all)

    If there is any truth to left turn vs right turn comfort and similar things its due to neurological dominance stuff IMO.

  35. check out pic number 45 in carlton reid's euro bike '09 pics. sort of dum, but ingenious ad for lazer helmets. ha!

  36. The only thing I can come up with to support this theory is that in much of the world traffic drives/rides to the right side of a road. This means that if a rider is on the right side of the road, spots an impending disaster ahead, brakes for all they're worth and accidentally locks up only the rear wheel (we all know that if you lock the front your ride is over) the rear wheel should tend to follow the crowning of the road downhill to the right as the front retains some control. If traction is not regained at the rear wheel the bicycle will lay down on its left side.

    In practice, I do find that my rear end usually does tend to slide to the right during panic stops. However, my worst example of this that I can think of happened one drizzly spring morning this year as a woman in a minivan pulled out in front of me on a long downhill. My real wheel locked and I began to switch ends (rear wheel to the right) BUT I was able to regain traction by feathering the brakes and was nearly flung off the bike to the right as it straightened out (and stood back up.)

    Another incident, this time only involving my bicycle and I, did result in a crash. It was another rainy morning on fast uphill, right-hand curve with an unexpected crosswalk. You can guess what happened when my front tire hit the paint. Much blood was shed. My left side was unscathed.

    Add one vote for BS, though.

  37. I've always unclipped left foot first, I thought due to being right handed, but then realized- when we were young- where was the kickstand-left side of course!

    I always fall to my right. Due to a recent crash, I can now attest that it's in everyones best interest to wear the temples of your glasses on the OUTSIDE of your helmet straps- less you loose a piece of nose skin......

  38. (coming late to the party...) As for me, my scars are all on the right. I've got some pretty good gouges on my right leg and around my right elbow.

  39. Stuff about falling to the left is rubbish BUT I do prefer to corner to the left.
    Good stuff to think about though, sometimes you just accept stuff in life and never thinking about it, it's good to stop every now and then to question things

  40. The comment about old racers and scared left elbows is very true for me, looking at mine. Most of my worst injuries have been to my left side, but I'm not going to subscribe to any theory just seems to be that way for me.

  41. Anonymous12:51 PM

    what the coach said may be true. the following excerpt is taken from an article on "The Dominant Leg"

    "...This left twist effect seems to be generally apparent in animals. Circus horses enter traditionally the arena on the right and circle left wards. Foresters know that a wounded deer will always run away left wards, even if the closest forest is to its right. Even bees tend to circle leftwards when they spiral upwards to gain height in the air.

    The basic driver behind this phenomenon seems to be the fact that all cells in nature are composed of amino acids which have a left spin. Chemists can manufacture amino acids with a right spin, yet we can't use them. Apparently both types of amino acids existed in the primordial soup at the beginning of life hundreds of million years ago. Yet life developed only from those with a left spin. The favorite theory is that at that time - when the earth did not yet have the protective ozone shield - radioactive rays from the cosmos did more harm to the amino acids with a right spin. Yet why those with a left spin would be more protected - if at all - is still a mystery."

  42. Anonymous1:01 PM

    "...People who are lost in the desert tend to walk in circles with a left spin, i.e. counter-clockwise.

    Most or our supermarkets are organized the same way: entrance is on the right, the cashier on the left. Studies have shown that customers tend to feel slightly stressed - increased cardiac pulse, elevated blood pressure, slightly faster walking pace - and buy less when they have to walk in the opposite direction.

    Same on the sports field: most track and field sports - from the 400 meter distance runner to the hurdle racer, they all run towards their left. Even the everyday jogger tends to run counter clockwise around the field or lake if he has free choice..." fromk an article By Simone Kosog in the science section of the 'Süddeutsche Zeitung Magazin' 1999.

  43. Anonymous7:48 PM

    I am not a cyclist, but have taken tunes down the stairs, on roller skates, etc. Four different falls and all were to the left. Interesting, huh?


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