Does your riding position influence the chances of head injury?

[bjlabuk]

Thanks for identifying the need to look for the evidence. But I don't expect to see it appear in this thread in this forum.

But you will probably get the traditional alternatives: whataboutery, changing the question, straw man arguments, ad hominem stuff, cherrypicking the data, anecdotage, tribal affiliation...

Jonathan

PS: Thanks to the posters who do use and promote evidence-based methods. Maybe one day the numbers will increase. Things can only get better!

With the greatest respect all this does is prompt the question "What do you mean by evidence?" or "What evidence are you looking for?" - We do not always mean the same thing when we talk of evidence.

There are many different types of evidence - legal and historical being two that spring to mind besides 'scientific'. If it is only the latter type that the forum owner is looking for then that should be made clear to everyone.

This thread is under the Topic heading "Helmets & helmet discussion". I have highlighted the word 'discussion' because the characteristics of a discussion differ from those of a 'debate' . I would suggest that some people here don't know the difference between 'debate', 'discussion', dialogue', 'dictating', and 'diatribe'.

To your list of "straw man arguments, ad hominem stuff" I would add appeals to authority, false analogy and false dichotomy fallacies.

Happy days.....

PS. I could describe my own riding position and give an opinion on whether I think it had any influence on my own accident, but what is the point? It would only be 'anecdotal'......

[Blondie]

You’ve got to distinguish between the speed you were going and the vertical speed your head hits the ground. Any speed parallel to the road surface doesn’t affect the impact speed and thus deceleration force when your head hits said surface.

[pjclinch]

You’ve got to distinguish between the speed you were going and the vertical speed your head hits the ground. Any speed parallel to the road surface doesn’t affect the impact speed and thus deceleration force when your head hits said surface.

Assuming you're hitting reasonably level ground and not e.g. a tree...
Also the case that there's more to head injury potential than breaking bones and concussion with a sharp whack: losing skin off your head is a head injury too, and my guess is you stand to lose more if your head touches down in a slide at speed compared to a fall from stationary.

And, of course, it could well be the case that however hard you hit the ground you're arguably more likely to have an off if you're going faster.

Pete.

[pjclinch]

On evidence based methods...

This comes down in significant part to a summary point of "can we measure the outcomes of interventions". See, for example, https://www.badscience.net/2005/12/what ... your-wine/.

Nobody's limited the discussion to formal evidence based methods here, the forum owner, Cycling UK, moderates but not for type of evidence, and if anyone wants to state their sincerely held conviction that a St. Christopher Medallion is a significant factor in road safety nobody will stop them... But nor is anyone reading that obliged to take it as seriously as something that measurably improves outcomes (like, say, evidential breath testing).

The reason evidence based methods are taken seriously is they are (done properly) verifiable, reproducible experiments so give a level of certainty beyond other methods.

Anecdotes aren't useless but they are typically qualitative and ephemeral in nature and for actual decision making quantitative and reproducible has a track record of working better. Working better leads to be more highly valued.

Pete.

[bjlabuk]

Interesting. Every road accident I dealt with in my career happened in real time, in unique cicumstances and conditions. No two accidents are ever the same. Neither are all road accidents reproducible under controlled laboratory conditions. In fact the Police carry out their own post accident reconstructions at the locus, in order to calculate such things as the coefficient of friction of the actual road surface.

Of course helmets can be tested in the laboratory just as vehicles can be tested in the laboratory by vehicle crash test engineers who plan and analyze safety tests for the automotive industry. But lets leave helmet testing aside for a while.

Researchers have to be aware of their limitations, and academics who feed off both researchers and Police data have to aware that they are not getting a complete picture on which to base decisions or suggest policy. This is clearly stated with regard to STATS19 data:-

https://www.gov.uk/government/publicati ... ty-report

To quote "The STATS19 collection is part of a larger administrative form that is completed by the police officer for each collision (or 'accident', the words are interchageable). This larger form contains additional fields about the collision that are relevant to the decision whether or not the police will prosecute any of the people involved. It also contains the police officer’s description of the circumstances of the collision, details of any witnesses and additional variables which are not shared for statistical purposes."

Where do you think the police get the "description of circumstances of the collision" from? It is by speaking to the people involved and to passers by who witnessed it, listening to and noting their anecdotal recollection of the events leading up to the accident. Then the officer, using their own judgement, based on their own knowledge of, and experience of, applying the law, decides the most relevant circumstances to record on the form.

Now if you want to dismiss all anecdotal evidence of both police and civilian witnesses, because it can't be objectively verified, and make decisions and suggest policy based purely on laboratory controlled reproducible experiments, then go ahead. I think you will be missing out on alot of valuable information.

[Blondie]

You’ve got to distinguish between the speed you were going and the vertical speed your head hits the ground. Any speed parallel to the road surface doesn’t affect the impact speed and thus deceleration force when your head hits said surface.

Assuming you're hitting reasonably level ground and not e.g. a tree...
Also the case that there's more to head injury potential than breaking bones and concussion with a sharp whack: losing skin off your head is a head injury too, and my guess is you stand to lose more if your head touches down in a slide at speed compared to a fall from stationary.

And, of course, it could well be the case that however hard you hit the ground you're arguably more likely to have an off if you're going faster.

Pete.

853’s post didn’t indicate any such additional hazards. But they did posit hitting ground at 20 mph which would be misleading if someone tried to use that to calculate the forces involved and type of head injury. Flesh wounds are part of coming off and often look worse then they are. A case for wearing long sleeves and gloves perhaps.

[pjclinch]

Data consists of enough anecdotes to give you something that is representative.

One is typically not much use. Depending on what you want to know there will be a number that is of use (so in the link I gave above, the folks who invented the wine magnetiser think their few bits of anecdotal evidence are good, but given a suitable sample size to collect sufficient anecdotes it can be shown far more convincingly that they're not)

What needs to be measurable isn't every last bit of each anecdote that makes up the data but the overall outcome.

Evidence based methods measure outcomes: purifying drinking water for a population sends the death rate measurably down, so we do that. That kind of thing.

As has been noted, the plural of anecdote is not data, it's a couple of anecdotes. But get sufficient so that you have a properly representative sample and they're recorded in a broadly comparable manner and it is data.

You said you were a stats-sceptic, concerned about garbage in, garbage out. Stats 101, too-small samples are garbage. A single anecdote is a too small sample beyond the person having it informing their personal experience in their particular context.

You also need to realise that "we cannot be sure if your incident was representative" is not the same thing is "your anecdote is meaningless".

Pete.

[pjclinch]

853’s post didn’t indicate any such additional hazards. But they did posit hitting ground at 20 mph which would be misleading if someone tried to use that to calculate the forces involved and type of head injury. Flesh wounds are part of coming off and often look worse then they are. A case for wearing long sleeves and gloves perhaps.

With no quoted post I was answering in a general sense, not concerning 853's post as I didn't realise that was what you were specifically commenting on.

Pete.

[bjlabuk]

Who is 'we'? Again, you are determined to judge my post based on some arbitrary rules you are dictating. Please state your credentials in full and how they make you superior to me.

Alternatively just accept that people use this discussion forum for different purposes, and ignore those that don't meet your arbitrary criteria.

I will continue to post what I like.

[axel_knutt]

Where do you think the police get the "description of circumstances of the collision" from? It is by speaking to the people involved and to passers by who witnessed it, listening to and noting their anecdotal recollection of the events leading up to the accident. Then the officer, using their own judgement, based on their own knowledge of, and experience of, applying the law, decides the most relevant circumstances to record on the form.

I recall a documentary series about police crash investigators, their lack of understanding was worrying. On one occasion there was some question as to whether the brakes on a car were working, so they checked by putting a foot on the brake pedal whilst someone grabbed hold of a wheel and tried to turn it. Not a clue that the force required to stop a car is somewhat greater than you can apply with a pair of hands.

[bjlabuk]

Not every accident is attended by an Accident Investigator. However yes, not all Accident Investigators are trained mechanical engineers, in which case they should get someone with the relevant qualification to do check out the brakes properly. I have also seen colleagues test the hand brake by applying it to 2 or 3 clicks and then manually trying to push the car forward. I don't know what happens now with electric handbrakes as I am retired.

I don't know what the Police use in E&W, but in Scotland a Prohibition Notice (PG9) is a ban on the use of a vehicle on a public road. A prohibition will normally be issued where a vehicle is found by an Examiner to be, or likely to become, unfit for use or where driving of the vehicle would involve a risk of injury to any person. Not all officers are qualified to issue PG9s. But a qualified PG9 officer should know how to examine and test the brakes of various types of vehicle.

[pjclinch]

Who is 'we'? Again, you are determined to judge my post based on some arbitrary rules you are dictating. Please state your credentials in full and how they make you superior to me.

Alternatively just accept that people use this discussion forum for different purposes, and ignore those that don't meet your arbitrary criteria.

I will continue to post what I like.

Nobody's trying to stop you posting what you like as long as it's within the forum's politeness guidelines.
Whether anyone will think it's actually useful is down to them, as is whether they wish to comment on how they perceive the value of what you post.

I will judge any posts according to my own ideas, just as you will judge any posts by yours. I don't really see why that's meant to be fine for you to do but frightfully bad form for me to do

If I think your posts don't stand up I'll say so, just as you say that about mine. I have no idea why you're on about credentials or why you think anyone disagreeing with you is some nefarious attempt to control debate.

Pete.

[bjlabuk]

Read....

[drossall]

The against (compulsory) helmets tend to use arguments drawn from statistics the Germany and the Netherlands.. those for (compulsory) helmets tend to draw statistics from other countries...

Just for the record, I would question this premise. Those questioning the case for helmets do point out that casualties are low in the Netherlands and, possibly, Germany. Those arguing for compulsory helmets do not obviously look at other countries for statistics. It's not really about where the figures come from.

A more accurate statement would, I think, say that the case for helmets is itself made more strongly in the Anglophone countries, reflecting a difference of approach to cycling and safety. Also, the case for helmets more often (though far from always) assumes that the statistics are bad without actually checking into the detail. But neither side is cherry-picking by country in quite the way that you imply.

[Blondie]

853’s post didn’t indicate any such additional hazards. But they did posit hitting ground at 20 mph which would be misleading if someone tried to use that to calculate the forces involved and type of head injury. Flesh wounds are part of coming off and often look worse then they are. A case for wearing long sleeves and gloves perhaps.

With no quoted post I was answering in a general sense, not concerning 853's post as I didn't realise that was what you were specifically commenting on.

Pete.

Quoting posts is clunky in this forum unless you are quoting the full post. Clearly if you do t read posts in sequence you might miss the context.