Forum: bicycles.stackexchange.com
Tags: <road-bike><speed><injury>
Title: Do higher speed crashes result in less serious injuries.
Question: I have heard that the severity of injuries tend to decrease while riding a road bike at high speed. An instance of high speed would be like those in the Tour de France.  The reasoning behind this idea is "enough" speed allows the cyclist to "roll" upon landing thus decreasing the chance of breaking bones for example.   This seems contrary to my basic knowledge of physics and momentum, so, is it true?

Answers:
sents: text: In " Epidemiology of bicycle injuries and risk factors for serious injury " by Frederick P Rivara, Diane C Thompson, and Robert S Thompson, the authors gave a questionnaire to 3,390 bicycle riders who had attended a hospital emergency department in the Seattle area.
text: They found that cyclists involved in a crash at a speed greater than 15 miles per hour were 1.4 times as likely to have a "severe" injury (defined as an injury severity score greater than 8) as cyclists involved in a crash at a speed of 15 miles per hour or less.
text: The 95% confidence interval was 1.0 to 1.9.
text: (Caveats: 1.
text: It seems strange to me that the authors only reported odds ratios, when they apparently had the data to compute effect sizes too.
text: 2.
text: The fast cyclists differ systematically from the slower cyclists: the odds ratio fell to 1.2 when other factors in the study were controlled for.
text: 3.
text: It's Rivara, Thompson and Thompson.)
answer_details: author: bicycles.stackexchange.com/users/756/Gareth Rees
score: 19
sents: text: As far as I know, in any vehicle, there is a direct relationship between speed and severity, statistically speaking, with "lots" of studies showing that.
text: This also applies to being hit, or front-to-front crashes.
text: There's even the term "high-energy-trauma", applied by health professionals to injuries involving high energies, for example high kinetic energies.
text: Of course there are confounding factors: are fast riders (professional riders?)
text: more skilled?
text: Are fast racing events the place for a more "focused" riding?
text: Do they fall less, or are someow more prepared to fall?
text: Anyway, I cannot see how a SLOWER fall could hurt MORE than a fast one.
text: It's a matter of kinetic energy, speed of response of human motor coordination, even common sense.
text: Although I have not evidence to bring about, I hope this helps someway.
answer_details: author: bicycles.stackexchange.com/users/2355/heltonbiker
score: 6
sents: text: It is totally dependent on the impact.
text: If you run into a wall you want to be going slower.
text: If you hit a bump and are launched off your bike or jump off a cliff you want to be going faster.
text: I don't know physics well enough to explain it that way
text: but I do ride a lot of street (jumping down stairs, off roofs, etc.)
text: so I will explain it how I know you want to land in that sense.
text: Think about the angle of impact jumping off a loading dock, if you drop going at a slow speed you will impact the ground almost at a 90 degree angle, your body will need to absorb almost all the impact (on a non-suspension bike).
text: If you go faster you will impact the ground at say 45 degrees, you will feel a lot less impact on your body.
text: Taking that to the tour de france (or crashing in general, even on a jump), if you roll rather than slide, your impact on the ground will be a lot less at higher speeds, your chance of twisting a leg or whatever is less because your limb doesn't have time to get planted.
text: It might help to watch some parkour, they will roll out of a jump because they are trying to transfer the impact at an angle against the ground rather than absorbing an impact perpendicular to the ground.
answer_details: author: bicycles.stackexchange.com/users/3949/BillyNair
score: 3
sents: text: I think there is likely no clear answer.
text: The points go both ways.
text: Yes at speed there is the ability to roll.
text: But also the risk of trauma with a stationary object.
text: Be it an object or the ground.
text: Humans are soft and squishy with fragile bones compared to concrete and asphalt, rocks or trees.
answer_details: author: bicycles.stackexchange.com/users/3124/Matt Adams
score: 1
sents: text: Those who can and do ride at higher speeds are generally fitter, often younger, and more able to bounce back from an injury.
text: These speedy types have learned to be situationally aware, and are more alert to their surroundings and the proximity of obstacles.
text: When I noticed this when riding quite fast on an ebike...
text: I was looking around a lot more and riding much more defensively so
text: if an obstruction were to appear, I already knew where my runout spaces were.
text: Having had one significant-speed whoopsie myself that was caught on camera, I can say that perception of time really does slow down when its all going badly.
text: Perhaps thinking "this is gonna hurt" is the key.
answer_details: author: bicycles.stackexchange.com/users/19705/Criggie
score: 1

Summary of the answers:
Studies show that cyclists involved in crashes at high speed are more likely to have serious injuries than those involved in crashes at a slower speed. However, people who ride at higher speed tend to be fitter and more able to bounce back from an injury. Moreover, the type of impact makes a differenceç if you hit a wall, you want to be going slowerò if you hit a bump and get launched off the bike you want to be going faster as you will hit the ground at a better angle.
Academic studies have shown a positive correlation between speed and severity of injury on bikes, and this is true with other vehicles too. However, faster accidents may be correlated with fitter and younger riders who are more aware of their surroundings and able to respond to risks and falls, as well as being able to recover quicker. Hitting a stationary object will be worse at speed, while falling off at speed might deflect the force sideways.