Cycle helmets don't reduce head injury risk as much as it's thought, claims new analysis

Norwegian risk and cost-benefit expert says previous research flawed

by Simon_MacMichael   April 13, 2011  

White cycle helmet

At a time when minister for cycling Norman Baker is in the headlines due to his choice not to wear a helmet while cycling, an academic from Norway has poured more fuel on the long-running helmet debate by claiming that they do not reduce the incidence of head injuries by the extent suggested by a meta-analysios of previous studies. Moreover, he says that by considering head, face and neck injuries as a whole, there is "no overall effect" through wearing a helmet.

Dr Rune Elvik, an expert in risk analysis and cost benefit analysis from the Institute of Transport Economics says that wearing a meta-analysis conducted in 2001 that claimed that wearing a helmet reduced the risk of head injury by 60% was flawed as a result of publication bias – in other words, more weight was attached to positive findings from the researchers’ point of view than negative ones – and time-trend bias.

According to Dr Elvik, "When these sources of bias are controlled for, the protective effects attributed to bicycle helmets become smaller than originally estimated."

He adds: "When the analysis is updated by adding four new studies, the protective effects attributed to bicycle helmets are further reduced. According to the new studies, no overall effect of bicycle helmets could be found when injuries to head, face or neck are considered as a whole."

His conclusions, based on an analysis of previous research, have been published in the journal Accident Analysis and Prevention, in an article snappily entitled Publication bias and time-trend bias in meta-analysis of bicycle helmet efficacy: A re-analysis of Attewell, Glase and McFadden, 2001 which, in layman’s terms, points out what he believes to be flaws in that study and provides a reanalysis of its findings.

Dr Elvik employed a variety of techniques in his re-evaluation of the findings, conclusing that “the re-analysis shows smaller safety benefits associated with the use of bicycle helmets than the original study,” according to the article overview, which adds that “the findings of this meta-analysis are not consistent with a recently published Cochrane review,” published by the not-for-profit Cochrane Collaboration.

In New Zealand, where bicycle helmets are compulsory, the findings were reported by the NZ Herald, which adds that Dr Elvik also argues that an analysis of several studies published recently shows there was “no net effect” through sporting a helmet once injuries to the head, face and neck were grouped together, because helmets increase the risk of the latter.

Professor Alistair Woodward, head of the School of Population Health at the University of Auckland and a cyclist who himself wears a helmet, told the NZ Herald: "Cochrane is usually regarded as the gold standard in pooling studies and deriving a conclusion.
"It's reasonably clear to my mind that helmets do protect people's heads and on balance they do more good than harm," he continued.

However, he agreed that helmets were not intended to guard against neck injuries.
"Whether they cause the neck to bend more than otherwise, I suppose it's possible. If there is an effect [on neck injuries], it's much smaller than the protective effect from head injuries."

Professor Woodward said he was in accord with the conclusion that modern, lightweight helmets with a soft shell protected the head less than older ones with a hard shell.

"The first helmets were [made for] rock-climbing,” he explained. “Only later, people realised the energy-absorbing material inside the shell is probably what's more important ... and the surface of the helmet has become more vented and less rigid," Professor Woodward added.

 

31 user comments

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What ever the rules / results I shall continue to wear
one ... a ride recently saw a rider go down and suffer
some fairly hefty head trauma that would, imo, have
been FAR worse had he not been wearing a lid.

still on the 3rd switch-back of Bwlch !

posted by therevokid [699 posts]
14th April 2011 - 9:14

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Gerard, do you wear full downhill-style body armour when you're cycling to the shops? Or wear a full race harness, fire-proof suit and helmet when driving in town?

The use of all of those things would also reduce your injuries, after all ...

timlennon's picture

posted by timlennon [227 posts]
14th April 2011 - 10:12

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Here we go again

I would ***dearly*** love to see just one of these articles go by with a horde of people coming out the woodwork with the anecdotal evidence of why I should be forced to wear a helmet

For the record - while cycling on the roads I wear a lid, because it makes my wife relax a bit about my cycling - when on cycle paths I hang the lid on the bars.

So to make it 100% clear - I only feel unsafe while cycling around motor vehicles.

Can anyone else see the obvious safety improvement? Time to ban cars completely.

posted by mad_scot_rider [546 posts]
14th April 2011 - 10:21

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The truth is, most of these studies are a farce, be they 'pro' or 'anti' helmet.

You just can't recreate an accident on a bicycle easily. At least not the way that it's possible with cars. Any data taken from hospitals is only indicative as you can't ask the patient to go out and perform the exact same accident with/without helmet.

It's all pretty simple though. If it's law, then unless you like paying tickets, abide it. If it's optional then make your own choice- but be prepared with the potential consequences that not only you, but your family, friends and loved one will potentially have to deal with.

In other words, I'll happily strap a helmet on any day.

posted by Shiny Flu [84 posts]
14th April 2011 - 10:28

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Quote:
You just can't recreate an accident on a bicycle easily

there's no particular reason why you couldn't recreate bike accidents like car manufacturers recreate car accidents, so far as i can see. except the fact that it's a hugely involved and very, very expensive process. who's going to spend the money? car manufacturers do it because it's a high value product and safety is a major concern. if you're knocking out a million cars at twenty grand a pop then it's worth the outlay. you'd need to sell a *lot* of helmets to justify the kind of money proper crash reconstruction would cost.

and governments? well. much easier to hop down a&e and ask if anyone banged their head, and make a call on that Plain Face

Dave Atkinson's picture

posted by Dave Atkinson [7325 posts]
14th April 2011 - 10:39

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TRL has already carried out research and conculuded a 10-16% reduction in fatalities would result from wearing a helmet.

http://www.trl.co.uk/online_store/reports_publications/trl_reports/cat_r...

However... "It does not include detailed consideration of whether wearing (or not wearing) a helmet influences the likelihood of being involved in an accident, either through behaviour changes in the rider or in other road users."

it also assume the helmets are worn properly.

posted by ribena [136 posts]
14th April 2011 - 11:38

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Actually - and this is a bit of an epiphany - I've realised what's really wrong with the helmet debate: too many people don't even wear the bloody things right anyway.

Chap walked into the chemist with his daughter. She had a scooter, and a helmet which was too loose and tipped back. I politely suggested it wasn't fitted right, and he said 'yes, I know it's a bit loose - I need to sort it out'.

And I thought, why waste money on it if you're not going to then use it for its intended purpose?

timlennon's picture

posted by timlennon [227 posts]
14th April 2011 - 11:42

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As ever, news items like this ditrract attention from two key points:

1. unlike car seat belts and motorcycle helmets, there is no conclusive evidence that cycle helmets deliver material benefit at a macro level - the assertion that a helmet provides protection in "X"% of cases doesn't deal with the overall incidence of head-injury accidents (low) or the potential impact on take-up of cycling if helmets are compulsory
2. constant harping on about the dangers of cycling in order to talk up helmets gives an entirely false impression of how dangerous cycling is, which is not very, compared with DIY, walking, travelling in a car etc. Stats show that head injury per hour for cycling is slightly higher than walking, slightly lower than travelling in a car, and stats per kilometre show cycling a lot lower than walking, although higher than car travel (due to obvious speed differences)

You can all say you wear a helmet and think it is a good idea - I do too, off road or in icy winter conditions - but don't tell everyone else that they should.

posted by Paul M [309 posts]
14th April 2011 - 13:19

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I've been cycling decades and don't remember the last crash where I hit my head or helmet - and that's not because of a head injury! Legs and arms seem much more at risk and most people don't armour those.

Nevertheless, I wear a helmet unless it's awkward to store at my destination. So if you want to increase helmet use, campaign for more lockers by bike racks.

posted by a.jumper [698 posts]
14th April 2011 - 13:46

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mad_scot_rider wrote:
For the record - while cycling on the roads I wear a lid, because it makes my wife relax a bit about my cycling - when on cycle paths I hang the lid on the bars.

So to make it 100% clear - I only feel unsafe while cycling around motor vehicles.

Actually, I believe you are more likely to have an accident on a cycle path than on a road. Accidents on the road have the potential to be more serious, but collisions on bike paths are more likely, because of cyclists travelling in opposite directions on narrow paths, pedestrians, dogs, overhanging vegetation etc... So your helmet is probably more useful on the bike path.

two wheels good; four wheels bad

posted by cat1commuter [1339 posts]
14th April 2011 - 14:05

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Bike helmets are useful no matter where you ride. On road or off road. When 10 I was knocked off my bike by a lorry and hit my head on the kerb resulting in concussion and a stay in hospital. A helmet would definitely have prevented that injury.

More recently I have fell off my bike and again each time my helmet has prevented my head hitting the ground.

posted by raymondox [2 posts]
15th April 2011 - 17:08

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Sorry to hear about the accident, therevokid. But the rider sustained 'fairly hefty head trauma' despite wearing a helmet -- which suggests it didn't work very well. And you are probably wrong to say that the injuries would have been much worse without it. If the helmet breaks, it won't have helped much at all. I read somewhere that a 25 mile/hour crash without a helmet has the same energy as a 21.x or 22.x mile/hour crash with one (can't put my hand on the exact figures but that is as near as I remember).

I agree that whether to wear a helmet should be a personal choice, but the benefits of helmet wearing are frequently overstated.

posted by arowland [84 posts]
15th April 2011 - 17:45

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Definitely the case its a St Christopher talisman for many children. Very few have their helmets secured properly, ready to strangle etc.... Also risk compensation will absorb some of benefits - riders will push it more if they're wearing.

I wear one when I ride in unpredictable conditions icy and when compelled to - triathlon. A visor is great to keep snow and rain out of the eyes!

Dunbar, Scotland

posted by mjcycling [13 posts]
15th April 2011 - 17:57

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Totally agree about poorly fitting helmets.

Dunbar, Scotland

posted by mjcycling [13 posts]
15th April 2011 - 17:59

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Wellllll, the helmet worked for me when I fell off after the front wheel found a kerb edge in the dark and I was thrown down the road - I felt the foam crush as the helmet destroyed itself. The safety glasses seem to be good at keeping bugs out of my eyes and I know the little sods hurt like hell when they get IN my eyes. The reflective vest didn't stop me having to shave across the front bumper of a car in the dark in a typical SMIDSY in Switzerland, but to be fair the guy who nearly terminated me was dazzled by the lights of the line of cars on the road behind me (I was on the cycle lane in the RH gutter), and the gloves seem to keep my hands warm enough so they must help a bit. Basically, I'll do what I think works, why don't you lot just do the same and save yourselves a load of nervous energy?

ChrisS

posted by Chris S [42 posts]
15th April 2011 - 18:00

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arowland wrote:
Sorry to hear about the accident, therevokid. But the rider sustained 'fairly hefty head trauma' despite wearing a helmet -- which suggests it didn't work very well. And you are probably wrong to say that the injuries would have been much worse without it. If the helmet breaks, it won't have helped much at all. I read somewhere that a 25 mile/hour crash without a helmet has the same energy as a 21.x or 22.x mile/hour crash with one (can't put my hand on the exact figures but that is as near as I remember).

I agree that whether to wear a helmet should be a personal choice, but the benefits of helmet wearing are frequently overstated.

I used to work for a bike manufacturer, and one of our sponsored riders had a pretty big 'off' where his helmet was smashed into many small pieces, only held together by the internal lattice. According to him, he landed head first whilst travelling around 50 odd km/h. He only had a mild concussion. Blows your argument to pieces now, dunnit?

Helmets are a simple way to reduce the likelihood of trauma to the brain which, unlike other body-parts, cannot be transplanted, sowed back on, or grow back without major implications, and it's no more awkward than a seatbelt.

posted by Ciclismo [19 posts]
15th April 2011 - 20:05

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Ciclismo wrote:

I used to work for a bike manufacturer, and one of our sponsored riders had a pretty big 'off' where his helmet was smashed into many small pieces, only held together by the internal lattice. According to him, he landed head first whilst travelling around 50 odd km/h. He only had a mild concussion. Blows your argument to pieces now, dunnit?

No it doesn't. One argument is based on science the other is based on what some bloke told you of an incident you have no first hand knowledge of, the outcome of which may have been affected by any number of variables – it certainly can't be extrapolated up in to a population wide argument for helmet wearing.

In the Dutch we have an example of a population that cycles in vast numbers and wears helmets in miniscule numbers - they don't seem to suffer a greater incidence of head trauma amongst cyclists as a result, quite the opposite in fact.

Helmets are only designed to be effective in an impact up 12mph, I can't remember seeing any helmet manufacturer shouting about their helmets being safer at any higher speeds - in fact they don't seem to shout about the safety benefits at all. There sole contribution in recent years has been to water down safety standards or undermine those they regarded as too stringent - most seem to market their products based on comfort, ventilation and looks, not their safety.

Denzil Dexter's picture

posted by Denzil Dexter [140 posts]
15th April 2011 - 20:25

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To provide a contrast to the very first post which came from a Kiwi, let's look at the NZ bicycle helmet law:

It is an overwhelmingly political success, and even has widespread support among the bicycling community.

However it is also a health, safety and financial disaster which has not reduced the injury or death rates by one iota.

Other countries choose not to pass these laws based on the results in NZ and Oz.

So why do so many Kiwi's still support the law? Well it's called the placebo effect - hand out sugar pills and a significant number of people will feel they are of benefit. It works great for bicycling:

  1. first take a relatively safe activity which is an overall health benefit and make it into a dangerous one - its called creating the market
  2. now promote a "solution" to the "problem" you've just created - you've a product to sell after all
  3. persuade some idiots to make your "solution" law - laws are hard to rescind (politicians, even more so than most of us, don't like admitting mistakes) and give you a liability out - "we just supply the legal requirement, don't blame us when fails"
  4. wait for the accidents, people will believe they've been saved by the placebo on their heads. You'll also probably get more accidents, as people feel "protected" or when motorists assume bicyclists are, which helps keep the belief in the danger. You'll also get a lot of parents refusing to let their kids bike anymore, its "too dangerous due to the traffic" - even though your "solution" doesn't actually work in traffic at all...

Neat, tidy, stupid, dangerous, lethal - welcome to bicycle helmet laws.

There are far more people in NZ post-law who've been "saved" by their helmet then were ever injured/killed pre-law!

Of course some will tell you the above is just rubbish.

Let's agree with them for a moment. The Australians, who the Kiwis just copied, have done the maths - if bicycle helmet laws work then there are much bigger gains ripe for the picking. Drivers wearing seatbelts in air-bagged equipped cars still get injured and killed, would bicycle style helmets help? Of course, to the tune of A$350M/year or 17 times as many lives saved... Wow!!!

So why don't the bicycle helmet law promoters wear them in their cars?

One or two do, the vast majority don't - it's not the law you see...

But wouldn't they if they really believed?

So maybe the above wasn't rubbish after all.

posted by Another Kiwi [1 posts]
16th April 2011 - 1:07

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Has anyone at road.cc actually read the paper (even the conclusions)? It's hard to understand how you could have come up with the headline you have if so.

For the benefit of those who won't even read a paper that you can access free online, there are four conclusions. None of them state that "wearing a helmet reduces the risk of head injury by 43%".

In fact, this figure is only mentioned in the Elvik paper you're reporting on in the introduction, where it is observed that the number is not reliable because of publication bias (amongst other issues).

The interesting conclusion of the paper is "no overall effect of bicycle helmets could be found when injuries to head, face or neck are considered as a whole."

Honestly guys, this is embarrassing. The paper is freely available and in plain English, you can just read it for yourself. Professor Woodward must have been leaping for joy that someone was asking him to comment on something as mundane as "only 40% effective" when the paper actually says "no overall effect"....

(Please feel free to email me if you need help with this, genuinely - I'm guessing you can see the address I registered with.)

posted by EdinburghFixed [2 posts]
18th April 2011 - 20:42

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Hi Edinburgh Fixed, thanks for the input. Yes, the "no overall effect..." finding for head, face & neck injuries is newsworthy and we did mention it, but then like most cyclists we wouldn't expect a cycle helmet to afford much, if any extra protection to the face or neck anyway. Even so you make a fair point and we've given that more prominence now.

We've also rewritten the reference to 60% and deleted the one to 43% - those were cited in the NZ Herald report that drew our attention to Elvik's study, and it turns out, appears to have misreported it.

As for the headline, we're happy with that - as the conclusion says, "When these sources of bias [in Attewell] are controlled for, the protective effects attributed to bicycle helmets become smaller than originally estimated."

As for the paper being "freely available on the internet," it didn't appear to be when we first wrote the story, but it was available on Elsevier Science Direct, where it cost $41.95 to access.

However, we've found the full paper online now - it's at www.cycle-helmets.com/elvik.pdf if anyone is interested (this appears to be the January 2011 version rather than the final published version).

Apologies if we missed that first time round - but if we go to the source in good faith and the article is locked, then a website whose home page suggests it focuses on "Mandatory bicycle helmet law in Western Australia" is not an obvious next port of call. That's ignoring whether or not the paper was reproduced with Elsevier's permission.

The cautious approach from our point of view would of course have been to ignore the story full stop without having access to the report itself - but then of course we wouldn't have had the benefit of the debate in the comments above on a subject that clearly continues to inflame passions on both sides.

Simon_MacMichael's picture

posted by Simon_MacMichael [8036 posts]
19th April 2011 - 0:24

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arowland wrote:
tIf the helmet breaks, it won't have helped much at all.

Helmets are designed to break in a crash - by doing so they absorb an awful lot of energy that would otherwise crack your head. It's a similar strategy to "crumple zones" on cars.

posted by lovelyali [1 posts]
19th April 2011 - 8:18

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Road CC, I'm impressed with your objectivity and willingness to publish corrections (and to defend and explain your postion when readers object).

I'm surprised that some of your readers are so opposed to wearing helmets. They seem willing enough to don tinfoil hats.

http://en.wikipedia.org/wiki/Tin_foil_hat

Viro

posted by Viro Indovina [79 posts]
19th April 2011 - 12:24

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"Helmets are a simple way to reduce the likelihood of trauma to the brain which, unlike other body-parts, cannot be transplanted, sowed back on, or grow back without major implications, and it's no more awkward than a seatbelt."

Why is that logic applied almost exclusively to cyclists?

I don't know the New Zealand statistics, but I know that in most other developed countries, over 98% of serious brain injuries are to non-cyclists. Pedestrians are at far more risk per km than cyclists, and completely overwhelm cyclists in the total HI count. Surely, if we could just get helmets on pedestrians, we'd have five times as many "My helmet saved my life!" stories. Ditto for motorists.

As with bike helmets, most of those stories would be false. An oversized, easily dented hat is bound to get lots more bumps than a bare head, and scare the wearer every time it happens. And the resulting tale adds more fuel to the "biking is really dangerous!" hysteria.

DS

posted by DS [1 posts]
20th April 2011 - 19:08

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dave_atkinson wrote:
there's no particular reason why you couldn't recreate bike accidents like car manufacturers recreate car accidents, so far as i can see.

The difference is that in a car, the driver doesn't effect the outcome very much. Especially when a seatbelt is worn, there is relatively little difference between a heavy, light, tall or short person.

On a bike, the rider provides most of the weight. The difference in body position is also far greater when compared to a car. The rider position differs hugely between a Dutch bike and a pro race bike.

posted by Aapje [167 posts]
21st April 2011 - 9:55

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in car crash testing you narrow down the infinite range of possible crash scenarios into something you can actually test, and the outcome is a set of standard tests that mimic the most common collisions. I don't see why you couldn't do that for helmets: no you can't test for everything, but that doesn't mean you can't test for anything. car manufacturers already test for collisions with pedestrians, where bodyweight and position at impact affect the outcome just as much as they would with a rider and bike.

Dave Atkinson's picture

posted by Dave Atkinson [7325 posts]
21st April 2011 - 10:10

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Fine, I guess we shouldn't wear helmets. Screw it, we shouldn't have brakes on bikes either because the absolute majority of vehicles involved in fatal accidents have brakes. And while we're at it, why don't we stop breathing, because 100% of people injured also inhaled oxygen at some point.

posted by Ciclismo [19 posts]
21st April 2011 - 23:09

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Learn to break fall. As martial arts instructor I can recommend it will help. lol

oh yes while i on one - take a motor bike - great way to learn road awareness, road position and better ability to read the road.

I wonder how the accident incidents would be improved more if there was better skills from those that get hit by cars.

Point is question - I have been taught that when turning left you look down tour left hand side to make sure nothing as come down the side and well as the other side to make sure nothing is coming round the outside.

In fact you should be aware of all around you and scanning to signs of possibly problems ahead.

Now while riding round London. Watch cyclists. There is really no awareness of what is going on a round you. Every single close scraps I have had was due to me taking my scanner off line for a second, maybe a nice pair of pins sauntering down the road. But I have never had an accident.

I am sure better riding practise is more practical and produce better results than just wearing a helmet. Me I can never concerntrate with one of this things plonked on my head. I would rather give up cycling if I had to wear a helmet.

posted by Ciaran Patrick [117 posts]
10th June 2011 - 20:25

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I have come off, a mates have come off, we were both wearing helmets, if we werent, I wouldnt be typing this now.

Simple as.

posted by PhilWalker [31 posts]
27th June 2011 - 12:25

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raymondox wrote:
Bike helmets are useful no matter where you ride. On road or off road. When 10 I was knocked off my bike by a lorry and hit my head on the kerb resulting in concussion and a stay in hospital. A helmet would definitely have prevented that injury.

No, sorry, not necessarily. Helmets are tested to protect against falling off (a quarter-kilo free-fall IIRC). If you are knocked off, you will probably exceed the protection of many legal helmets.

raymondox wrote:
More recently I have fell off my bike and again each time my helmet has prevented my head hitting the ground.

Yikes! Why do you keep falling off?

PhilWalker wrote:
I have come off, a mates have come off, we were both wearing helmets, if we werent, I wouldnt be typing this now.

Err, prove it? I wonder how much difference helmets made. Again, why do you keep falling off?

PhilWalker wrote:
Simple as.

That sounds a bit kiwi...

posted by a.jumper [698 posts]
27th June 2011 - 13:57

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a.jumper wrote:

raymondox wrote:
More recently I have fell off my bike and again each time my helmet has prevented my head hitting the ground.

Yikes! Why do you keep falling off?

Raymondox is really Denis Menchov AICMFP Wink

Simon_MacMichael's picture

posted by Simon_MacMichael [8036 posts]
27th June 2011 - 14:33

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