Cycling helmets

I have heard all sorts of reasons why cycling helmets are unnecessary, undesirable or counter-productive. This article is a rebuttal of some of these extraordinary views.

Cushioning an impact

RATE of energy transfer is closely related to acceleration (hit by car) or deceleration (as car occupant); a change in velocity over a shorter distance is higher accel/decel. (Measured over time this would equivalently be a change in momentum, and so the impact is IMPULSIVE over time. Impulse analysis tends to be used for things like billiard ball collisions (you can draw the analogies yourself!) because the impact is pretty much instantaneous, at a point on the table, not over a distance. In such impacts, kinetic energy is not transferred perfectly (e.g. heat and sound consume some) but momentum is transferred.)

Grand Prix drivers like to have run off areas, and/or something equivalent to rubber tyres beyond that at the side of the track to increase the distance over which energy is transferred, thus reducing deceleration. But they still wear helmets for all the reasons argued in this article. Yes, the helmets are bigger and more robust, but the speeds are correspondingly much higher, and in general, helmets at the extreme are still designed to act like crumple zones (a painful analogy in this case) to increase that distance over which energy is transferred to the head.

Crumple zones and road rash

No helmet, and the crumple zone is one’s skull, at best, whether more or less than 11mph at impact. If the head hits the road, there is NO vertical distance over which energy is transferred other then the human crumple zone.

In terms of the horizontal “component of impact”, quite apart from all the abrasive “road rash” effects, there may well be rotational effects induced, and for this reason there is research into new helmet designs that are double layered to allow the helmet to rotate without rotating the brain stem, as, to some extent, human skin does!

Helmets for pedestrians?

Pedestrians are supposed to be separated by pavement kerbs and pedestrian crossings, and to a great extent are protected in that way by the law. Erefore to argue that cycling helmet wear is as ridiculous as asking pedestrians to adopt specialist walking wear is fallacious logic. Compare the protected pedestrian situation with the extraordinarily bad design of many bicycle lanes! Bike riders share the road much more intimately with vehicles than pedestrians as a matter of routine, so there is a compelling argument for SOME protection for riders as opposed to walkers.

Helmet wear might deter other improvements?

I of course agree cycling policy is due a major review with regard to making our roads and behaviour bike friendly, but this is not an either-or argument. To say that prudent cyclist behaviour will tend to transfer blame perceptions and reduce the willingness for other policy changes might or might not be the case, but why ask people to take more personal risks – might this be in the expectation that this might help the business case for change through higher cyclist injuries and deaths?!

Do we really need to go through the seat-belt controversy on bike helmets?

On the matter of organs hitting the human shell, skull or ribs or whatever, this is also a feature of seatbelt use, but no-one would argue nowadays we shouldn’t use seatbelts to ameliorate that effect as compared with hitting the interior of the car or its controls.

But a the time seat belts were being introduced, and being made compulsory, there were all sorts of arguments made against wearing em. People even pretended to wear them by draping them across the chest without fastening gem. Incidentally, this is why large cars are safer than small cars, irrespective of make; you are less likely to come into contact with roof or doors or other parts of the adjacent car shell, assuming seatbelt use. I guess airbags help reduce that differential.

Speaking of seatbelts and air bags, there is an argument made by some that safer drivers means less safe pedestrians (and presumably cyclists) because the driver suffers less consequences of an accident and so tends to drive more recklessly. Are we to argue seatbelts and airbags should not have been introduced owing to this psychological effect? I don’t think so. Ditto the argument re helmets and bike lanes etc.

Helmets are a sacrificial protection

A family friend’s child wearing a helmet ran into a tree on his bike and severely damaged his face and base of skull resulting to two consecutive maxilla-facial operations totalling 12 hours (and thankfully he made a good recovery minus an olfactory nerve). The surgeon was relatively elderly, commenting that this was lucky for the boy, because younger surgeons get much less practice at such injuries now that everyone wears seatbelts in cars – less windscreen / face impacts. In that incident, the helmet came off worst, but it was felt that it saved even further damage by absorbing some energy while being destroyed. This was a 12 year-old going downhill – somewhere in the region of 20mph maybe?

Helmets only work below 11 mph, so why bother?

I have heard this argument a few times. An analogy is with car accidents – most happen writhing 10 miles of the driver’s home. Not because the roads are more dangerous there (a logical nonsense to think so, think about it!) but because most drivers spend most time within that distance of their home.

Similarly for helmet use – in towns, and possibly elsewhere, most cyclists spend most of their time below 11 mph. So the argument that it’s not worth wearing helmets because of higher collision speeds is fallacious from that point of view. I would also argue that even if it is tru that helmets are unlikely to save injury above 11 mph, there are many collateral abrasions that can be ameliorated by a helmet. But any reasonable view is that the helmet is always likely to be of some benefit.

Helmets and the law

This article isn’t necessarily to argue for compulsory helmet use, but to argue that helmets (and light coloured visibility wear) should be used by all cyclists as a matter of common sense.

But common sense ain’t so common, and I would argue that if people can’t respond wi reasonable actions to protect themselves,mthe law has to step in. It’s just too disastrous for the individual and too expensive for society for people to cycle unprotected in contradiction to such common sense. So let’s encourage helmets to our friends and avoid the need for legislation.


Corrupted Garmin file and correction

After many rides with both my Garmin and also Strava on my iPhone, I had stopped recording rides on Strava on the phone as it eats the battery.

But I was caught out at the weekend as one of my Garmin files was corrupted, and wouldn’t upload to Garmin’s site or to Strava. Disaster! 😉

I thought I would follow up on my idea that the tcx (xml) file, which I looked at in Dreamweaver (I’m a part-time and very old-age web developer!) was corrupted, but probably very slightly.

The Dreamweaver diagnosis is full of unrecognised tags, but then it would be because it is set up to look for html tags, not exercise application tags. It did throw up some syntax points, but hard to spot the wood for the trees.

So I researched the web for a dedicated xml file validator / editor, and found one which did both (most only validate). The one I used was Altova, on a 30 day free licence.

Unfortunately, most applications are Windows based, and I use a Macbook, but I have a Windows partition on it (Bootcamp) for just this kind of situation, and so sent the corrupt Garmin file to myself to open in email there (for obvious security reasons you can’t write to Bootcamp partition from the OSX partition) and went to work for what I thought might be a lot of wasted time.


There was ONE error in the file, an extra tag between an ending and a beginning tag.

I tried simply deleting the tag thinking it couldn’t be that simple, but IT WAS! The file then saved with no errors (ALTOVA warns you if you try to save an invalid xml file) and I immediately tried and upload to Strava, and that WORKED.

Click here to see that ride. It looks exactly what I was expecting, and completes my Spring Classic challenge (hence my urgency! – how childish…).

Looking back, I think the reason for this has been pausing and un-pausing the Garmin too quickly – when it is off-course, you gat a visual waring of that, but lose the screen space for warnings that you have paused or unpaused it; there is only a slightly different audible tone for pausing vs. unpausing, and I did it a few times at one point on the ride just to make sure it was on. I can’t be certain, but I think something like that must have happened. I guess the Garmin starts a new track every time it pauses or auto-pauses? And it opened a but didn’t have time to close it? Maybe…

Anyway, I attach the corrected text for your delectation!

If I can be of any help to anyone else who gets this issue, let me know (I’m sure an exported .fit file, as a binary file, even if I could have corrected it, would not have responded to such easy treatment. Flat, text-based xml files (tcx in this case) are a lot easier to handle.

I’d be interested in your comments and any further light anyone can throw on it.

PS Here is the offending piece of file, with the orphan tag in bold:

Corrupt Garmin code segment
Corrupt Garmin code segment