Today was rainy in Palo Alto and I was driving home in bike lane. My bike slipped and I felt off my bike in a part of bike lane that was made of concrete instead of asphalt(here). I didn't injured and I am fine.

When I was falling down I didn't know how to shape my body to protect myself and prevent serious injuries. What should I do in situations like this?

  • 9
    Although answers on Stack Exchange tend to be quick, they're still not quick enough to appear between falling and hitting the ground (unless you're Felix Baumgartner).
    – gerrit
    Commented Jan 10, 2013 at 10:24
  • If you're about to crash into something, rather than fall, then you have a choice. Leave your hand on the handlebar and break your collarbone. Or put your hand out to try and save yourself, and break your wrist. I'm only being half-flippant when I say this, since judging by the people I've spoken to over the years, one or the other is likely to happen.
    – PeteH
    Commented Jan 10, 2013 at 14:43
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    @PeteH Wear cycling gloves with a padded "heel". I've fallen more than once without breaking anything. For example landing on earth is easier than landing on hard concrete: even a little padding is a better than none at all.
    – ChrisW
    Commented Jan 10, 2013 at 17:13
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    @ChrisW I've only fallen the once. At 30mph. It was onto (or rather into) an earth bank by the side of the road and I was wearing mitts. Fortunately it was not concrete but I still broke my collar bone ;-) But seriously if ever I needed convincing of the value of a helmet.... I try not to evangelise about whether people should wear a helmet or not... to each their own.... but I firmly believe that the fact I was wearing one that day saved my life.
    – PeteH
    Commented Jan 11, 2013 at 16:47

11 Answers 11


I'm going to assume you're a bright Stanford kid, and that your brain will remember this.

Work = F * d

Work = Force * distance

Try punching your arch nemesis for an instant. Just hit him for a second and as soon as you touch him, pull your hand back. Nothing happens.

Now when you punch, punch behind him. Keep pushing, all the way through, pushing pushing pushing. Whoa. Can you believe your own strength? That guy just flew across the room. You can try this with a punching bag, too. Whatever you like.

So when you punched your grandma or whoever, you had a lot of force but you didn't keep applying it over a distance. When you push push push then you do a lot of work to your poor grandma.

So basically the ground/fire-hydrant/tree is going to do a lot of work to you. That amount of work isn't changing, no matter what.

So you've got

WORK = force * distance

Notice how work is bold here. Imagine work is written 10 feet tall on a chalkboard to represent how big work is here.

Now if your distance is small, the force is going to need to be... (guess)

very big.

WORK = FORCE * dist

Now if you can find a way to extend your distance.... the force you experience will shrink.

So if you can extend your legs, extend your hands, do a parkour/Ta Kwon Do roll, something, that will dampen your fall.

Another example. Someone hits a baseball super deep into back field. You're playing without a baseball mit. Say you just hold your hand steady and catch it all at once. SMACK. That really hurts your hand. Now say you extend your hand all the way out, and as the ball lands in your hand, your arm moves back until your hand is at your chest, absorbing the blow. Ahhhh. No sweat!


work is going to be same-same

Force needs to be small

so make distance big


The guys comments make a very good point. A lot of people get injured by extending their limbs. What's happening is they don't give their limbs room to bend. They brace for the fall by extending their arms/legs too far out, to protect their body/head. Instead they get locked. OUCH. Extend your arms/legs, but don't lock them forward. That's just going to make the distance very small again, and it's really going to hurt your joints.

So extend, but don't lock your elbows/knees.

Good point guys.

Think of it like falling. Don't lock your legs all the way forward. That's... really going to hurt. But if you extend the toes of your foot, bend your knees a little, and give that ground a good SLAP with your hands when you're landing, that fall is going to feel like butter. You can practice absorbing falls on a set of stairs. Go up one step, jump off, extend your feet/legs, and practice absorbing the whole fall. Then go up another step. Keep working at it until you can run off the top of the stairs and land on the bottom (if you're intense like that). You'll notice that the difference between the 10th step and the 11th step is HUGE. And the difference between the 11th step and the 12th step is INSANE. But that's another physics lesson.


The physics does not apply exclusively to spherical bodies. If you can extend your slide to 35 feet instead of 30 feet, you will SIGNIFICANTLY decrease the trauma you experience.

"Kinetic" energy = moving energy = (mass * velocity^2)/2

velocity = distance/time

That means with any change in velocity will SQUARE the energy.

When you talk about collisions, you're talking about momentum. Specifically the change in momentum ("impulse of momentum") or change in mass * velocity

mass * velocity = Momentum

Mass is staying same-same.

Velocity is changing from 20MPH to 0.

That's a huge CHANGE in momentum.

If you increase the distance of that change in speed 5 ft (16% of 30ft), you decrease the change in momentum.

So remember to find a way to roll if it's safe. Don't add more energy to the impact by rolling into the collision, unless you're going to get substantially more distance. For example, if you're falling and you know how to land on your feet and instead of SLAPPing the ground, you roll forward over your shoulder, that's going to be even better. It takes a little training to learn how to forward roll like that, and I'm assuming that the best way to think of this is simply. I like my models to be simpler than the actual thing I'm describing.

So just think: how can I increase the distance of this collision? I don't want to BOOM hit the pavement all at once. I want to soften the blow by sliding more, absorbing some of the impact, whatever.

I'm not a medical doctor and I don't know very much anatomy. Something tells me we evolved to protect our heads and bodies for a reason. That's where all the really important organ stuff is. The problem with people who crash a lot, like skateboarders, is they tend to fuck up their limbs before they become experts at falling. Just don't lock your elbows/knees by over extending them.

  • Second, and probably most important advice: try to brake before the accident. Changing the speed before your collision will reduce the energy SQUARED. Again, try jumping off your stairs. Falling from 13ft is way way harder than falling from 10ft. That's because the little extra speed you have when landing gets squared as kinetic energy. Think of energy as the potential to do work. Like the floor having the potential to work your body into jello.
  • Wow, telling people to brake is probably the first advice I should have given.
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    This is a decent answer - but it needs to be a little less sensational. The repetition is fine if you're in a lecture delivering the answer, but as a written piece it could be made shorter and snappier - and better laid out. Worth a +1 but it really needs tightening up.
    – Unsliced
    Commented Jan 11, 2013 at 9:45
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    I think the actual advice in this answer is dangerous. First, I remain unconvinced that anything you can do during a wreck will significantly increase or decrease d. But worse, what actually causes serious (non-head) injury in a bike wreck is usually having limbs broken while tumbling. Extending your arms and legs is an extremely bad idea, and will more likely than not contribute to broken limbs. Commented Jan 11, 2013 at 20:00
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    Stated differently, the physics provided considers your body as a singular mass, and recommends an approach that may marginally decrease overall force experienced by your body while significantly increasing the risk substantially higher forces on localized parts of your body (e.g., limbs). Unless you are a perfectly spherical mass (hey, I'm not judging here), this advice gets the physics (mostly) right but completely ignores context. Commented Jan 11, 2013 at 20:04
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    Even given the update, I believe that this advice is dangerous and misses the point. When you are involved in a crash, the number one priority is to protect your head. The number two priority is to protect your limbs. Period. Considering the physics of a fall assuming you are a spherical body is irrelevant to the forces experienced in an actual crash, and any reduction in force you experience from extending your deceleration is immaterial unless you are crashing into a solid obstacle like a wall. Your body does not experience significantly more trauma in a 30ft slide versus a 35ft slide. Commented Jan 25, 2013 at 0:20
  • Actually, the last thing you should worry about protecting is your limbs. Head is obviously the first, but before the limbs, there's a lot of other things you should protect. I think the order goes head, neck, spine, torso, then limbs. While you may think that a broken arm hurts, it's way better than getting a broken rib, or even worse, a broken neck. It's usually not a huge problem to fix a broken arm, even though it may put a dent in your cycling season. Also, I've known people would rode with broken arms.
    – Kibbee
    Commented Mar 26, 2013 at 13:28

I suggest following a short course in some martial arts class where you can learn to fall correctly (Judo would be my suggestion)

there is nothing you can read that will prepare you for a fall and that will suppress the reflex to stick out your arm to catch yourself (and possibly break it); only practice will have you instead tuck in that arm provide a convex surface to the ground and roll it out

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    +1 for martial arts training. I know its totally impractical to say do this kind of training just so you can have better reflexes for falling off your bike. Having said that my jujitsu training (also like judo has a lot of breakfalls) probably saved my life, or at least some broken bones when I hit a car who pulled out in front of me. I went over the handle bars and landed flat on the windscreen with bend arms protecting my body and head. Years of training to land face down safely. Otherwise learn how to skateboard, falling down will train you to fall properly.
    – robthewolf
    Commented Jan 10, 2013 at 8:48
  • Rugby will also get you there.
    – Jaime
    Commented Jan 10, 2013 at 15:21
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    Actually, given the severity of accidents I had with a bike compared to the injuries I had to some Judo training that I had at the age of 7-8. You cannot plan accidents, so your reflexes have to be adjusted todo the "right thing"
    – StefG
    Commented Jan 16, 2013 at 7:20
  • Is there any way other than martial arts classes to get such training?
    – amcnabb
    Commented Mar 26, 2013 at 20:48

There's not much more to say than: tuck your head, protect your face with your arms, relax, and wait for it to be over.

Realistically, though, you're not going to remember the contents of this post the next time shit hits the fan and you find yourself tumbling on the asphalt. But if you can manage any of these things, you'll hopefully minimize the chance of breaking an arm or scraping the hell out of your face.

  • +1 for “tuck your head”. Lowering the chin as a reflex is simple enough to learn quickly, but could save a life in this kind of situation.
    – Agos
    Commented Jan 11, 2013 at 22:19

To some extent, you can actually "learn" to fall. The problem is that the learning has to be "motor learning" and not just thinking about it.

In other words, you have to train your nervous system to do it through practice.

Some of the best bike handling I've ever seen has been from people who ride single track (mountain biking). This type of riding involves lots of wipe-outs. As a result these riders develop very good body-english skills. And these skills translate to road-riding as well.

On the other hand, there are conditions where no amount of preparation can help you because everything occurs so fast you don't have time to move your body even if reaction response is instant.

  • Yes the "motor thing" is the problem and only comes with tons of practice.
    – Javier
    Commented Jan 10, 2013 at 19:16
  • Beyond mountain biking, do you have any recommendations about how to learn to fall?
    – amcnabb
    Commented Mar 26, 2013 at 20:49
  • Not really. It is a motor skill. You just have to practice it, and that means actually falling. It is just much safer to do it at slow speed on relatively soft ground! Freestyle riders do practice on concrete but these are typically people in their teens to early 20's with virtually unbreakable bodies!
    – Angelo
    Commented Mar 27, 2013 at 14:14

In my experience, things happen so fast it is practically impossible to react with some kind of plan. I have fallen over when I couldn't unclip fast enough (in other words, when the bike was stopped at a light or similar), and those were the only times where I knew I was falling and could actually spend a fraction of a second looking for something to grab, or trying to figure out how to land.

All the other times-- in other words, when my bike was moving-- it happened so fast that it seemed I was on the ground looking up before I could really do something intensional.

I suppose if you live on the bike, you may become skilled enough to where you can recover from some crashes (see Peter Sagan right around 4:50 in this video for an example), but even if you're very skilled, there isn't much you can do in many circumstances, except perhaps try to learn from them so you don't repeat mistakes.

I'll give you an example. A few weeks ago I was riding behind a friend-- a skilled rider, many years of experience-- and in a bike tunnel which goes under a road, there was some sand in our lane. He did not see the sand, and when his bike went over it, his hands were jarred from the bars, and he went down, right in front of me. It was all I could do to slow down and try to avoid hitting him and his bike. What did he do right? He wore his helmet. What did he do wrong? His grip on the bars was too loose. Hopefully he will relearn that lesson (I'm sure he knew it already). All it takes is a moment of inattention. But what could he do? He was on the ground in a fraction of a second.

BTW, you might be well-advised to carry some basic first-aid stuff. Something to clean patches of road-rash, and that kind of thing. Riding in an urban environment, you probably don't need an extensive kit like mountain bikers often carry, but you might get a good idea of what you might want to select from looking at such kits.

  • +1 for a small first-aid kit on longer rides. Outdoorsy shops often have readymade ones that do fine as long as you religiously replace whatever you use out of them.
    – D.Salo
    Commented Jan 10, 2013 at 13:09
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    One first aid item that many people have but don't think of is your water bottle. If it's reasonably pure water (and not energy drink or whatever) it is excellent for first-aid treatment of road rash -- cleans the wound and stops the sting. Add in a small bottle/tube of antiseptic and some gauze pads and tape and you have most of what you need. Commented Jan 10, 2013 at 13:17
  • @DanielRHicks +1 for using your water bottle. Having to remove a fresh scab to clean the wound underneath was more painful than the initial shredding on coarse sand. Commented Jan 10, 2013 at 18:01

My instinct is to put my arms out in the hope of protecting my head and face. Good quality gloves will help your hands from getting cut up. Also needless to say, wear a helmet.

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    That's a great way of breaking your wrist. Not very good advice.
    – Jaime
    Commented Jan 10, 2013 at 15:21
  • @Jaime probably, but better than breaking your skull/face/jaw. At least the elbows can bend absorbing some of the impact.
    – Mark W
    Commented Jan 10, 2013 at 15:32
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    after which you hit yourself in the face; your arms aren't meant to have you land on them, best thing is to roll out someway Commented Jan 10, 2013 at 17:43
  • when your going over the bars there's not much option.
    – Mark W
    Commented Jan 10, 2013 at 17:49
  • It's pretty difficult to stop your hands from coming out; there is great footage of professional motorcycle racers' hands coming out at speeds over 100mph. I'm told that's the reason the wrist area of their gloves is reinforced, for what little good it does. Commented Mar 27, 2014 at 11:34

As an ex BMX rider I feel quite confident to fall (you crash alot when you try things). But that's not the case for commuting/road bike, in fact you can't do anything, maybe beside falling on mats (and still it sounds weird to practise it). What really could be good is building muscles that will hold your bones in place, when you flip over. Anyway, the best thing to do is to ride with care and not to fall at all :-)


Yes, martial arts is the way to go and I am talking from experience. I am a black belt in ju jutsu and I have my brain "fully programmed" for falling correctly. Once I had a frontal collision with another biker and was uninjured because I fell correctly. But all this is easily said than done.

Start here: http://judoinfo.com/ukemi.htm The first one, the rolling technique is what I did.


Ride a mountain bike and fall a bunch. Usually less chance of getting hurt on trails and it does train you to fall right without thinking about it. Probably not practical if you don't own or care to own a mountain bike, or you have no trails nearby. That said, if you go down on pavement at speed your going to get hurt at least a little, and sometimes it happens so fast that no amount of muscle memory is going to help you. That's where proper gear comes in.
Appropriate gear goes a long ways when you crash. At the minimum you need a helmet... always. Gloves are also fantastic for getting chewed up in place of your palms as you will inevitably put your hands out to catch yourself if you can.


Fortunately I haven't had much practical experience with falling, but I'd always been told to stay clipped in, hold on to the handlebars and land on your side. In my single bike accident I did this and came out mostly unscathed, with a few minor scrapes.

If I were willing to put in the practice and teach my body to fall, there are probably more effective things to do, but without lots of practice and some muscle memory using the right form, I don't think I'm going to be able to do anything fancy. WHen I had my bike accident, I didn't have time to think about what to do, I just fell and I don't recall making any conscious effort to hold on and fall, it just came naturally.

Here's an article that advocates the hold on and fall technique:


  • The only time I ever fall is when I realize, too late, that I forgot to unclip. Commented Mar 27, 2013 at 20:39
  • Ahh, then you're already half way there to the "hold on and don't unclip" technique :-) My fall was caused by a child that swerved into me on a bike path, I ran off the path to avoid him and ended up on my side. No conscious effort went into the fall.
    – Johnny
    Commented Mar 27, 2013 at 20:43
  • This works if you care about the bike less than you ;) Commented Mar 27, 2014 at 11:35

This cannot be taught. No matter how much theoretical advice you seek and how much you think about it, you'll never learn how to fall if you don't fall often, especially at a young age.

After years of BMXing I think that one needs 10-100 falls to start becoming better at it.

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