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Bicycle Helmets

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A cyclist's bicycle helmet

Bicycle helmets have been around for a while - indeed, early riders of high wheelers often used to wear bowler hats1 to protect their heads in case of spills. Recently there have been moves to make helmets compulsory when riding on the road. Here are some of the facts you need to form a balanced view.

Many of the facts below seem, on the face of it, to suggest that helmets are not worthwhile. This could not be further from the truth; helmets are an excellent idea. Children in particular should wear them every time they get on a bike. The point is, although there is no guarantee that a helmet will save your life if you come off, it's 100% certain that your helmet won't save your life if you're not wearing it.

How They Work

Old fashioned helmets were an arrangement of padded bars, the gaps designed to allow air to flow. They were OK to wear, you could pull a balaclava over the top on a cold day, and they offered some protection.

For the last decade and more the standard helmet has been made of polystyrene with some kind of abrasion-resistant cover. The helmet works by collapsing in a controlled way, rather like crumple zones in cars. Collision energy is absorbed by the destruction of the helmet.

This leads to one of the absolute fundamentals of modern cycle helmets: if your helmet has been in an accident throw it away immediately. The chances are it will have been fatally damaged, even if you can't see the damage.

Choosing and Fitting

There have been several conflicting standards for helmets, varying from the useful to pure marketing hype.

The first reliable standards were probably those from the Snell Foundation, although in the early days they modelled rather unrealistic circumstances, they have since improved. In the US these helmets will also have to pass a Consumer Product Safety Commission (CPSC) standard, and for most competitions, an ANSI certification is required. European standards bodies BSI, ISO and DIN do not currently list any applicable standards. Any helmet sold in the EU will be CE marked - this means nothing, as CE marking does not imply any kind of fitness for purpose, only a licence to sell in the EU.

Your helmet must fit properly without slipping about (as this report shows). Better models have an adjustable cradle at the back of the head which allows very precise fitting. Make sure that the helmet doesn't press against your skull, as this rapidly becomes uncomfortable. Adjust the chinstrap so it's as close to your neck as possible - you need to be able to open your mouth to yell at motorists. Remember: if your helmet slips on impact, it won't protect you.

There are cheap helmets on the market. One or two of these might be good, but it is fair to say that most are not. A good helmet might cost between £50 and £100 (2002 prices) - the more you pay, the lighter, more comfortable and better ventilated it is likely to be. Detachable visors are a good idea in the summer (and they keep some of the rain off in winter).

The helmet will probably come with various foam pads which can be stuck or velcroed in place to improve fit. If the helmet does not fit reasonably well without these, it doesn't fit. The pads are just to fine-tune for comfort, not to rely on for fit. Distrust immediately any helmet which only comes in 'Large' and 'Small' - or, worse still, one size with a plethora of various thickness pads.

What Helmets Are Good For

Helmets are primarily designed to protect against injury in the event of a single-vehicle accident at speeds up to around 12mph. A single vehicle accident is one where there is no other vehicle involved - ie, you fall off. These limitations are primarily due to weight and ventilation considerations: motorcycle helmets are better, but far too bulky, heavy and restrictive for use on bicycles.

Only 8% of reported injury accidents involving bicycles are single-vehicle accidents2, and 50% of head injuries sustained are on areas which are not, or would not have been, covered by a helmet.


These figures do not apply to children. Inexperience, and the use of bicycles for play, increases the risk of the kinds of accidents for which helmets are designed. 80% of these accidents take place off the road, so would not be covered by any helmet legislation. Compulsory helmet wearing by children when riding on the road would result in an estimated two lives saved per annum compared with a situation where no children used helmets. It is noticeable that levels of helmet wearing amongst children are higher than for adults.

It seems that education and promotion is already effective in the area of helmets for children, and in areas which could not be covered by road traffic legislation, which necessarily cannot cover private off-road areas such as BMX ramps.


Despite the fact that they do not protect against the most common types of accident, helmet wearing is becoming more common among adults - again, with no compulsion exercised.

This is partly due to the feeling of safety which helmets provide(although this is to an extent illusory), partly because modern lightweight helmets are not too intrusive and may have a sun visor which is handy in bright sunlight (ie, twice per year in the UK) and partly because if you go over the handlebars of a safety bicycle, the first thing to hit the ground is your head. However unlikely such an accident might be, the consequences are so severe as to make wearing a helmet attractive.

Sports Events

Many sporting events require the use of helmets. This especially includes Audax events (long-distance time trials) and mountain bike events. The reasons for this are specific and sound: in sporting events people ride closer to the limits, and spills are more common.

The Case For Compulsion

Cyclists are vulnerable, but giving them separate space on the roads is expensive. Compulsory helmet wearing is a 'safety measure' whose costs fall entirely on the cyclist; no government is spending required. It is an attractive quick fix.

An obvious comparison is with motorcycle helmets. Compulsory wearing of helmets has reduced deaths of motorcyclists due to head injury by a significant amount, but the comparison doesn't stand up. Cyclists are killed in Britain at a rate of 53 per hundred million passenger hours3, but the rate for motorcyclists is 382 fatalities per hundred million passenger hours - seven times higher.

The Case Against Compulsion

The case against compulsion rests on two main facts: first, compulsory helmet wearing leads to a reduction in cycling, which is profoundly undesirable in a society where obesity is rapidly approaching epidemic proportions. Second, the kinds of accidents which worry the politicians, cyclists being knocked off by cars, are not the kinds of accidents against which helmets provide any protection.

Subliminal Messages

Helmet promotion (without compulsion) would seem on the face of it to be sound, but even here there is a risk: the promotional materials create an unwarranted perception of cycling as a risky activity. It isn't. Yes, cyclists do occasionally get knocked off and killed, but on average they live around ten years longer because they get regular cardiovascular exercise. You will live longer - provided you live.

There is also a question as to whether it is ethical to suggest that wearing a helmet will protect a cyclist in an accident. The range of accidents in which a helmet is of use is narrow and specific, so unless there is a large amount of small print there is a danger of false reassurance, leading to potential risk-taking. The best protection, after all, is to avoid the crash in the first place.

Risk Factors

Lorries in particular are dangerous to cyclists, there being a 25 times greater likelihood of death in a cyclist versus-lorry-crash than in cyclist-versus-car. In accidents involving motor vehicles and cyclists, the motor vehicle is to blame in two thirds of cases - but the cyclist is, unsurprisingly, 37 times more likely to be killed or seriously injured than the motorist. Even then, cyclists are statistically less at risk than motorcyclists. This suggests that driver education would be a good place to focus attention.

The best protection against cyclist vs. lorry crashes is the provision of advance stop lines and cycle lanes on the approaches to junctions. Studies show that this simple and relatively inexpensive measure is approaching 100% effective in preventing the worst lorry-versus-cyclist accidents. Thus, cyclists are out of the danger zone to the left of the lorry (where they may be out of the field of vision of the driver's mirrors, and where the road can suddenly vanish as the lorry turns left). Education is also an important factor, both for cyclists and lorry drivers. Deaths are generally due to crushing injuries, and helmets play no significant part.

Factors Increasing Safety

Figures for cyclist deaths and injuries decrease with increasing prevalence of cycling. The UK death rate of 53 per hundred million passenger hours is on a base of an average 62km cycled per person per year. In Holland the death rate is 23 per hundred million on a base of 850km per person per year, and in Denmark the rate is even lower - 18 deaths per hundred million hours on a base of 1,050km per person per year.

These figures have been reasonably consistent over time, and indicate that the very best way to improve road safety for cyclists is to encourage more people to cycle. The reasons are obvious: more drivers will also be cyclists, and therefore be aware of the existence and needs of bikes on the roads; and the more bikes there are, the more drivers will expect to see them.

There is also good evidence that cycle lanes at least 2m wide, advanced stop lines, cycle-only phases at traffic lights, and good junction and roundabout design, are effective in increasing safety. Once again, the most survivable crash is the one that doesn't happen in the first place.

Helmets Reducing Road Safety

The most quoted example of the effect of compulsory helmet wearing is that of Australia, which passed legislation in 1991. The effect was immediate and dramatic: a 36% decline in cycling in the year after enactment. Research shows that recovery is slow. In Perth, in 2000 the reduction was still 15% against 1991 levels, although population had increased by 140,000 over the same period.

And, as the figures above suggest, fewer bikes on the road meant that cyclist injuries rose to their highest recorded levels. As a road safety measure it was - and remains - an own goal.

The Case for Wearing a Helmet, Even Though You Don't Have to

All the above makes it look as if cycle helmets have a negative impact on road safety. This is not so, it is just that the accidents against which they protect are not the kinds of accidents which are increasing due to declining driving standards, lack of compliance by drivers with road safety laws, and heavier traffic density.

They can offer protection in one important class of cycle crash: those due to poor road surfaces (these are a leading cause of injury to cyclists in the UK at present). Any cyclist who has bounced along the road on his or her head following a pothole-related wheel circularity modification incident will probably become a dedicated helmet evangelist.

Most club cyclists, especially those riding of road wear helmets. The helmet wearing rate in London is over 40% and rising. A helmet doesn't weigh much, doesn't interfere with your enjoyment of your ride, and is not seen as a big deal by most younger riders especially.

One Researcher's Story

I have worn a helmet since I was knocked off on a busy roundabout and rendered unconscious for over twenty minutes. One day in the summer of 1985 I was riding along wearing my helmet when an object became lodged in my front wheel. I went over the bars and crashed head first into the road. Although concussed I remained conscious and essentially unharmed. The bike, my prized Dawes Super Galaxy, was destroyed - frame, forks and front wheel all had to be replaced. But my head survived.

You will not find me on a bike without a helmet.


  • The DETR is now called the DTLR (don't forget to check out the current Highway Code while you're there).
  • For information on helmets and cycling in general, the CTC is the place to go - note this page.
  • You can buy helmets from the CTC or from high street stores such as St John Street Cycles, who should be able to help you choose the right one.
  • CycleSafe is a cycle safety initiative supported by all the usual suspects.
1A Derby for American readers.2Statistics are hard to gather; it is thought that there is significant under-reporting of these incidents although any accident involving hospitalisation will be counted.3DETR, Consultation on Transport Safety, 1999.

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