livedarklions

It's a counter example because your forward path is almost certainly not parallel to the ground--you are going to strike the ground at an angle such that the you would, if you were sufficiently dense and/or travelling fast enough, pierce the ground. The forward path parallel to the ground is the one you left when the wheels went out from under you. Yes, it is possible that you are being flung completely parallel to the ground, and will skip like a stone over water, but that's highly unlikely. It's much more likely that your forward path is right into the ground at some angle, quite possibly driving your head directly into the ground. In any event, you've now got us planning for a crash in a perfectly flat friction free universe as being our default rule. If I'm going to hit something, I'd much rather try to affect the angle of the collision than the landing because I think I'm more likely to succeed at injury avoidance riding a bike taking a glancing blow to the front wheel than flying off the bike into God knows what's actually there. Chances are rather excellent whatever it is is neither flat nor smooth.

mr_bill

You really ought to plan how to crash if you attempt to ride a bike in a friction free universe. The good news is you'll never go faster than 0 mph. The best news is you'll only fall once, since you can't get back up.

Kind of like climbing hills on a bike in zero gravity. So easy that it can't be done. (Ignore the what do you mean hill?)

Meanwhile, back in the real world....

-mr. bill

wphamilton

You're just fooling with me aren't you? The forward path is certainly parallel to the flat ground. The vertical path is towards the Earth's center. The resultant velocity - magnitude and direction - is the vector sum of both instantaneous velocities. That's the physical reality. If one insists on thinking about an instantaneous velocity, at some angle to the ground, then you're going to multiply that momentum by sine and cosine to get the resultant orthogonal forces and it turns out exactly the same.

And no, when I said (too much already) about spreading the force experienced from friction over time, and when I noted how to include the friction term in the initial impact, I am not talking about "friction free universe".

This is unproductive. Sorry folks. I honestly didn't realize that folks would not understand this, let alone argue about it.

livedarklions

Sorry, I was busy practicing judo throws with my bike.

mr_bill

Oh, I’m sorry, in your hypothetical “super-slick” universe it is almost ideal but there is still nano-friction?

Well, then, that’s COMPLETELY different.

So, instead of modeling the real world as a point mass and a velocity vector, let’s think about a ball with a “super-super-small” “super-super-dense” core surrounded by a “super-super-undense” thick shell. Assume the radius of the thick shell is a few orders of magnitude larger than the radius of the core. Assume all this is “super-super-rigid.” And the core and outer shell is “super-super-unslick.”

Ignore relativistic effects. Just the super-supers dominate your mere super.

Drop this jawbreaker from a one meter height, in one case with zero velocity and in another case at 200 mph horizontal velocity, 1g vertical acceleration down.

What happens next?

Is my “ideal world” more or less absurd than your “ideal world?”

p.s. Physicists explained semiconductors. Mathematicians created computing. But engineers developed computers, and internet protocols, and 200 mph motorcycles, and motorcycle helmets, and motorcycle “leathers,” and motorcycle airbags....

Ever wonder why MotoGP riders wear so much more personal safety devices than Tour de France riders?

-mr. bill

FiftySix

Anyone here the creator of this video?


Or, this one?

FiftySix

Certainly, their feet were hot from the friction of the shoes on the pavement, which is why they kept standing on one foot or another. Also for certain, there aren't many roads that smooth and ripple free around here.

IMO, to matter to this thread those Saudis would have to let go of the car and see how long they could stay on their feet.

I've done similar to the Saudis antics on my motorcycles to scrape oil or grease off the soles of my shoes after getting off work from certain jobs I had back in the day. But I never did let go of the bars or get off the seat. The soles of those shoes were always short lived.

mr_bill

No, but this one:


It took me many months to recover from the road rash.

p.s. I did not roll.

-mr. bill

livedarklions

I can't get past the fact that two people wanted to video themselves on rollers.

livedarklions

OK, so the next time I see a cannonball on a ballistic trajectory, I'll be sure to tell it to sort out the forward and downward momentums before it puts a dent in the ground.

shelbyfv

Apologies if this was mentioned earlier but is wearing a helmet a good idea if planning for a crash?

FiftySix

My sympathies for you are immeasurable.

Wilfred Laurier

On a tour last year on the Route Vert ('Green Road' bicycle path network) in Quebec, there were bollards at intersections between the trail and roads, and some of the bollard were starting to lean and make a very narrow passage through. I recognized the potential to have a crash at one of these spots. We went though about six or so of these intersections when the sleeping pad I had attached to my bars, sticking out a few inches on each side, caught on one of bollards and jerked my bars to one side, but I was prepared and, I was told, did a magnificent tuck-and-roll, and actually rolled back up on to my feet.

Sadly, I did not remember until about 50 km later that I had my glasses balanced atop on my handlebar bag before the crash.

63rickert

Roller races just can't happen any longer. They were great fun while they lasted. Never saw even one person come off the rollers until those videos were posted. Danger!!! Danger!!!

NeilBurt

Wear lots of bubble wrap. Get pads like kid rollerblades have. Get a wetsuit made out of inflatable life raft material and pull that cord before impact, and you should be okay.

RC71

I've certainly crashed more times on a motorcycle than a bicycle. On the motorcycle, after 2 years of crashing, I decided I knew exactly where the edge of the envelope was and decided not to crash anymore. That was successful except in actual sanctioned racing. Some bicycle crashes are almost unavoidable. Hitting a golf ball at speed as you enter a dark tunnel on a sunny day will most certainly take you down, following to close will leave you in the pileup.


Has anyone practiced flying from their bike?

The best strategy to minimize injuries?


So the best strategy I've enacted is spreading out the distance you (and your limbs) come to a stop. We don't have crush zones like a car but you can turn a falling motion into a roll so you don't have to absorb all the energy at once. Also, be sure your helmet takes the impact not your face if you're doing a face plant tuck your head. And remember if your hands go down don't catch yourself just slow yourself with a push-up not locked elbows and consider starting into a roll.

alanf

When I was a kid we used to bike to a park where there was a path with very fine sand on it and go like crazy down the hill and wipeout/slideout on the corners. There's where I learned most of it and when I took Judo I learned how to fall face forward straight forward/down, sideways and quartering back. A very valuable thing. Same when I parachuted. Also riding with clipin shoes teaches you how to at least fall a bit gracefully when you forget to get out in time.

Practice is best, however nothing really prepared me for the time a few years ago when I left a meeting with someone, extremely upset and went roaring off, peed off and made a terrible decision to go across a bridge that was made of metal grating and was coated with a very fine amount of water from a recent rainfall. As soon as hit the metal I knew I was in big trouble with my road bike. Even in a car this bridge is like driving on ball bearings. So I just hung on for dear life hoping for a soft landing or good karma to pull me through....

Well I got about a yard from the end of the metal when my bike slid out and I wiped out on my left side. Thank heavens I had winter gloves on, as I always do. At least then I only got a broken wrist rather than also mangled fingers. I also fractured my hip.

Thankfully the head nurse threatened me that she would kick me out of the hospital if I did not take pain killers because all this did was make me more determined to get the heck out of the place. My Tai Chi training was part of the trick in getting out of bed as I knew how to move properly to escape pain as my hip was unbelievably uncomfortable when I moved. One very wonderful nurse helped me when I practiced to get out of bed onto a wheelchair.

I was back at Tai Chi in three weeks and back on the bike in 4 wks and I avoid that stretch of metal like the plague.

79pmooney

I rode one of those bridges n a face. 1/4 to 1/2 mile. Flat. Over an estuary. It had rained just before; first rain in weeks. Race sewups. I rode it like it was ice. The challenge was that we were sharing the road with traffic going a little slower than us. I was behind a rider as we approached a car to pass. I elected to go the other way. He went down (before he got to the car; just a real ouch!). My ice skills pulled me though. (An answer to a different thread, but this is where my refusal to ride studded tires in winter paid off. I used all of that experience.) I shudder think of what that grating would have felt like and done to this skinny, bony body.

Ben

bgross

Depends upon the drugs. I seem to recall a particularly vivid conversation in ‘The Teachings of Don Juan’ that involved a black dog.
In a feeble attempt to keep this on topic... if you hit a dog you’ll probably be propelled over the bars.
Protect your face.
DAMHIK.

mjd420nova

Recent studies in the UK have found that the number of head injuries of riders with helmets has gone down but the rate of neck injuries is up. Believe it or not, your reflexes are quite sharp and genetic. Most instances are for the body to protect the important parts. The hands, shoulders and knees get the damage while protecting the head and neck. Tuck and roll is almost instinctive. The real worries and damage is from the resulting trajectory of the bicycle. Like ski's, snow boards, skate boards and water ski's, bicycles always find their way back to the rider after departure to inflict even more damage.

Rides4Beer

My leg is almost completely healed from a high speed downhill crash I had a month ago. I'm sure every crash is different, but in my case, I was able to anticipate the crash, there was that moment in the curve when I felt the bike start to slide, tried to recover, then realized that I was going down, so just stayed loose, held onto the bike and tried to turn my shoulder/hip when I hit the ground. Tore up my leg pretty good, but nothing was broken, was able to get back on the bike and ride 20+ more miles to finish the race. I think the only steadfast rule for crashing is don't stick your arms out, ever. Try to turn your back/hips to the ground if you can. That's about all you can do.

Also, I always thought the road rash argument for leg shaving was bs, but now having had to bandage my leg daily for a month, I can definitely see the merit. Although, at this point, there's no hair left anyway.

indyfabz

FIFY. My bike did not find its way back during my last crash, which resulted in a broken collar bone. Someone in front of me spit a stick out of their back wheel. It got spun up in my front spokes and lodged between the right side of the rim and the inside of the brake caliper, causing the front wheel to lock up at about 16 mph. I went flying sort of right and the bike sort of left.

livedarklions

Well, I got hit in the handlebars by a car last Saturday. Don't really remember landing even though I didn't hit my head, so not quite clear on the rolling thing. Ambulance ride, no fractures, but a really sore rib and thigh.

FiftySix

Glad to hear you weren't seriously injured.

Not sure why you'd want to personally participate in bike crash theory just for this thread though.

63rickert

Hit by a car in hip, shoulder, elbow you have a chance. Have never been hit in handlebar (except by another bike) and have wondered how it would go. "Really sore" sounds like a good outcome in a bad situation.