The CycleChat Helmet Debate Thread

[Fab Foodie]

They go well together. I know more people that got head injuries following gin than involving cycling.

I'm thinking of buying @Hill Wimp a thudguard.....

 

[mjr]

One reason for that might be publication bias. Someone's done the same sort of back-of-the-fag-packet calculations as I've just done, and realised that however hard they work the data nothing will come of it, so it will be a "boring" paper (from the perspective of a publisher).

There's two big things here: firstly, if we broadened it to injuries, might something come of it? The injury rates are likely to be many times greater than the death rates. I'd hope that in-race injuries have to be reported to the UCI somehow, possibly by the race commissaire or doctor.

Secondly, if the UCI cares about safety, shouldn't they be funding such a study and publishing it as Open Access? That they haven't seems like a sign that they're still more interested in sponsorships from helmet-pushers than rider safety or the popularity of cycling in general.

 

[srw]

There's two big things here: firstly, if we broadened it to injuries, might something come of it? The injury rates are likely to be many times greater than the death rates. I'd hope that in-race injuries have to be reported to the UCI somehow, possibly by the race commissaire or doctor.

Secondly, if the UCI cares about safety, shouldn't they be funding such a study and publishing it as Open Access? That they haven't seems like a sign that they're still more interested in sponsorships from helmet-pushers than rider safety or the popularity of cycling in general.

To your first point - if the answer (as I suspect it will be) is "no difference", then in the world of academic research that feels like a dull answer.

To the second - I agree that the UCI should do it, like the boxing organisation did. But they don't exactly seem to be the most with-it organisation, and safety considerations seem secondary to spectacle, and limited to making sure that motorbikes mostly don't run over riders. I suspect the helmet firm sponsorship is immaterial - compared with the profit available from a plastic hat, the profit from a bike or a bit of replica kit tat is much more exciting.

 

[swansonj]

The long answer is that you can draw some conclusions from the data, with a lot of caveats.

The first is that pro-racing cycling is a lot riskier than what the rest of us do. I haven't checked @mjr's data, but 150 days of UCI world tour cycling looks about right from their website. Let's say an average peloton of 150 riders, for 22,500 racing days per year. Fourteen years gives you 315,000 racing days, for a death risk of about 1 in 30,000 per day's racing. Compare that with the roughly 1 in 10,000,000 journeys in my most-often-cited paper, and even allowing for the increased journey time when you're racing over 150km or more compared with pootling through London the pros expose themselves to a significantly greater risk of death. Even though they're riding over largely closed roads, with police escorts and supposedly predictable motor traffic.

So drawing a conclusion from pro racing for the rest of us is always going to be iffy.

Now I'm beginning to get into harder maths at which I'm rather rusty, so someone might need to correct me. On the face of it, the death risk on any day pre-helmets was about 1 in 40,000; post-helmets it's (roughly) twice as much.

The appropriate model to use is probably the Poisson distribution, with a mean of 0.3 deaths per year. If I've looked up the right statistic, the standard deviation of the Poisson distribution is the square root of the mean, or 0.5 deaths per year. So the post-helmet observed mean of 0.6 deaths per year is less than even one standard deviation from the pre-helmet observed mean, and you'd have to make some really heroic assumptions to deduce any difference.

That's even before thinking about normalising for different numbers of race days, different peloton sizes, different racing conditions (more motorbikes and commissaire cars), different race lengths, and so on and so forth.

So it's certainly not possible to say that helmets have improved death risk. It's also not possible to say that helmets have worsened death risk. And death isn't the only risk to which pro bike riders are exposed.

I'm not sure that the best approach is to do the Poisson statistics on a single year (mu=0.3) as that overestimates the variance, given that we actually have 14 years available. But we could test whether n=4 is significantly different to n=7 as a 14-year average. It feels like fruitful territory for a t-test or possibly a chi-squared with one degree of freedom. I'd suggest the P value will come out at 0.3-something (two sided) or 0.1-something (one-sided), depending on the chosen test and assumptions.

So there's a 30-something-% chance that the change (as it happened, an increase) in fatalities would have happened just by chance, or a 60-something-% chance it's more than would have happened just by chance.

Someone will no doubt pop along to quote that P>0.05, but I'm sure you and I and all right-minded CC-ers can agree on the arbitrariness of 0.05. On the other hand, there are few contexts indeed where P=0.3 could legitimately be regarded as significant. But it's not a million miles off, suggesting that improving the power by including non-fatalities, or more categories of racing, might well produce something interesting.

As you point out, though, statistics can at most only tell us whether the change is statistically significant, not whether it was caused by helmets or any of the multitudinous things that also changed over a similar period.

Disclaimer: I will happily defer to anyone whose formal training in statistics is more recent than 22 years ago and who actually knows what they are talking about.

Why bother if it would be weak?

I'm taking a punt here, but I'm going to guess that you are not an academic researcher with an interest in statistics ....

 

[benb]

Someone told me I should wear a helmet the other day, because she knew someone who fell down the stairs when pissed and suffered permanent brain damage.
I suggested that being pissed was a much higher risk activity than cycling, and why wasn't she suggesting helmets for pissheads? Why do people feel the need to impart unwanted and patronising advice on a subject they clearly know FA about?

 

[Dave Davenport]

Someone told me I should wear a helmet the other day, because she knew someone who fell down the stairs when pissed and suffered permanent brain damage.
I suggested that being pissed was a much higher risk activity than cycling, and why wasn't she suggesting helmets for pissheads? Why do people feel the need to impart unwanted and patronising advice on a subject they clearly know FA about?

I once tried to cycle down some stairs when pissed which ended in rather spectacular failure (I think trying to do it whilst carrying a child's bike across the handlebars was too ambitious), luckily I was wasn't wearing a helmet so was unharmed.

 

[ufkacbln]

Someone told me I should wear a helmet the other day, because she knew someone who fell down the stairs when pissed and suffered permanent brain damage.
I suggested that being pissed was a much higher risk activity than cycling, and why wasn't she suggesting helmets for pissheads? Why do people feel the need to impart unwanted and patronising advice on a subject they clearly know FA about?

Been posted before, but probably worth repeating

Cohort studies that look at the whole problem of head injuries are interesting

The most common factor is alcohol and assaults following, then comes trips and falls

Cycling rarely features in these studies as a factor


Therein lies the real question we could save many more lives and prevent many more disabling injuries if all these groups wore helmets

Yet suggesting that these groups wear a helmet is immediately dismissed as very very silly

 

[ufkacbln]

New one for me, helmets prevent you from being drunk!!!!!!

From a classic "helmet saved my life" article in the sun

“
The 27-year-old was rushed to hospital – where he was treated by his colleagues at A&E – and went on to have 12 hours of surgery.

And had it not been for his £38 Giro road helmet from Halfords, Jose, of Yarnton, Oxon, says he is certain he would have died.

Spanish-born Jose, who works at Oxford’s John Radcliffe Hospital, said: “I shouldn’t be alive. That is what every surgeon that saw me told me.

“I broke my neck and it injured the nerve which controls the heart and lungs.

“When the surgeon came to see me my wife was there. He said it was a big possibility that I would wake up paralytic or I wouldn’t wake up at at all.

So the helmet not only saved his life, but sobered him up!!!!

 

[Racing roadkill]

Just a random question for those of us that actually do wear helmets...

Do any of you own more than one helmet and swap them around depending on your mood or the bike youre riding? Maybe you want to match the colors up with your bike etc etc.

Just curious as i bought a Kask Mojito in White/Black that ive worn for quite a few rides and i have to say that im so impressed with it im actually considering getting another in a different colour just to use on the commute or on days when theres going to be a chance of rain.

Generally speaking I know the whole concept sounds a little vain. but there are people in the world with more than 20 pairs of shoes

Yes. It's nothing to do with vanity either. I had 3 lids, one very aero, one aero, and one more conventional. The very aero one was 'used up' in a crash, and ( in the opinion of a medical expert) "did it's job admirably", the less aero one is the lid I use most often, as it saves me POWWWWWAHHHHH ( a few watts at least), and keeps water out of my eyes when it's raining, and the visor doesn't fog up, or slip about like glasses do,the other one is a spare.

 

[mjr]

Portugal steps away from the helmet crackpipe - https://ecf.com/news-and-events/news/important-victory-bicycle-users-portugal

Unlike the UK which did basically NOTHING for cycling in the 2015 revision of the Highway Code, Portugal seems to have helped cycling in its 2013 Road Code update.

 

[ufkacbln]

The very aero one was 'used up' in a crash, and ( in the opinion of a medical expert) "did it's job admirably"

So much for evidence based practice?

These are the same guys who applaud the efficiency of helmets in knee injuries!!!

 

[tommaguzzi]

When i fell on black ice and broke my hip the first question i was asked a hospital was were you wearing a helmet !!!!!?.

 

[Venod]

It was very nice this afternoon so I decided to leave the helmet off as I was riding alone, I was waiting to pull out at a busy junction when a full Sky Kit overweight individual on a bike passed in front of me, he said hi, then said you need a helmet, I was very tempted to say you need to lose weight and higher your ridiculously low seat but in the end I just ignored him, whats wrong with these people.

 

[ufkacbln]

When i fell on black ice and broke my hip the first question i was asked a hospital was were you wearing a helmet !!!!!?.

This is the hypocrisy and poor practice of some medical staff

If you were a pensioner with the same injury the question would not even be asked

 

[Justinslow]

Richie Porte and Dan Martins TDF crash.