Is helmet size really such a big issue?

[bert_is_evil]

Most people agree it's dangerous to wear a helmet that is too big, on the face of it this seems like good advice - you don't want your head rattling round in there right? But I got to thinking about it the other day..... say you have two riders (let's call them Bert and Ernie) who are wearing the same helmet except Bert's helmet fits perfectly and Ernie's helmet is a couple of sizes too big. Bert and Ernie are out for a ride and (shock horror) are not riding in staggered formation but instead precisely side by side. At the same moment Bert and Ernie T bone a cage that has driven through a stop sign and both go flying over the bonnet at precisely the same tragectory. Both land head first on the road the same distance from the cage. So what's the difference? They both receive the same benefits of the couple of cm of cusioning goodness from the helmet interior etc, the only difference being that the Ernie's helmet impacts the road a couple of mm's before his head hit's the inside of the helmet.
Is it really enough to make a difference? Or is the correct size issue more to do with other stuff such as strap fitting? Am I missing the point completely?

[yod]

it can come off

[Nagash]

And as Ernie's head slides down the road the back of the helmet rises and slips off Ernie's head leaving his face to fend for itself.

There's also other things.. I got a helmet as a gift and it was too big for me and when riding it would slip down blocking my view and i'd have to push it up again so I just use it for pillions now.. and it's better than my normal helmet! But yeah.. Visibility would be another thing.

[ManDownUnder]

Ernie's helmet is a LOT more likely to come off leaving a trail of "Ernie's High Protein Cranial Pate" to assist the investigators as they try to find the initial point of impact, and answer the question "where did his head go?"

[Sidewinder]

if you cant find one that fits dont wear one

[Sully60]

the only difference being that the Ernie's helmet impacts the road a couple of mm's before his head hit's the inside of the helmet.
Is it really enough to make a difference? Or is the correct size issue more to do with other stuff such as strap fitting? Am I missing the point completely?

The couple of mm that's needed for the impact momentum to increase so it's not a controlled deceleration anymore. Hmmm, no thanks!
Head injuries suck!

[Shaun]

To big a hemet, can also twist and break your neck very easy

[James Deuce]

Yes. The lining needs to be in contact with as much of your skull as possible to absorb the energy in an impact. If it isn't touching your head and the helmet will move relative to each other and the velocity difference between head and helmet will add to the force that your skull will be absorbing. This differential may be enough to kill you. If it turns on your head you may suffer facial damage. If it comes off you may not survive the next impact your head takes.

[bert_is_evil]

The couple of mm that's needed for the impact momentum to increase so it's not a controlled deceleration anymore. Hmmm, no thanks!
Head injuries suck!

But he's not travelling 2mm further. What if he was 1 foot shorter than Bert - his head would travel 1 foot further so is a couple of mm's really relevant?

[bert_is_evil]

Yes. The lining needs to be in contact with as much of your skull as possible to absorb the energy in an impact. If it isn't touching your head and the helmet will move relative to each other and the velocity difference between head and helmet will add to the force that skull will be absorbing. This differential may be enough to kill you. If it turns on your head you may suffer facial damage. If it comes off you may not survive the next impact your head takes.

So if a helmet is a few mm too big would adding a liner like a balaclava for example remedy the problem? I'm asking in theory - my head is snug as a bug in my helmet :yes:

[CookMySock]

I bought a helmet two months ago, and now it doesn't fit. It wobbles around and I constantly have to grab it and push it back into place. Not nice.

It might be something to do with the 1kg of fat I lost off my head, or whatever, but the thing is, it must fit or it will be very distracting and you don't need this shit while ur riding.

DB

[James Deuce]

So if a helmet is a few mm too big would adding a liner like a balaclava for example remedy the problem? I'm asking in theory - my head is snug as a bug in my helmet :yes:
No. A balaclava will only add microns, if silk or polyester, or maybe 0.5mm if wool.

A "few" mm sounds insignificant. It's not.

[James Deuce]

But he's not travelling 2mm further. What if he was 1 foot shorter than Bert - his head would travel 1 foot further so is a couple of mm's really relevant?
Yes. F=ma. Your head is accelerating relative to the helmet after the helmet has hit something. Nasty. Instead of absorbing the impact and spreading the load over the helmet shell and compressing the lining to protect your skull, the helmet potentially smashes on impact because there's nothing supporting the shell from inside, leaving it unable to spread the impact shock when your head catches up. Probably better off with no helmet than one too big. Too small is infintely preferable in the short term. Just right is best.

[bert_is_evil]

Yes. F=ma. Your head is accelerating relative to the helmet after the helmet has hit something. Nasty. Instead of absorbing the impact and spreading the load over the helmet shell and compressing the lining to protect your skull, the helmet potentially smashes on impact because there's nothing supporting the shell from inside, leaving it unable to spread the impact shock when your head catches up. Probably better off with no helmet than one too big. Too small is infintely preferable in the short term. Just right is best.

Ah right, now I see the difference - thanks! :sunny: < We need a smiley with a lightbulb going on over its head

[007XX]

Heck yes!

Having had an off as a teenager, with a head contact with the rear bumper of a car, I cannot stress enough how important a well fitting helmet is.

It's one of these things where trying to cut corners will cut your lifespan real short, real quick.

[F5 Dave]

I think Shaun's reply is largely relevant & often overlooked.

Especially by the turkeys that wear those hinged fronted helmets & ride around with the front sticking open. Gee, like that isn't going to break your neck even at 30kph.

[bungbung]

The ladies like my big helmet

[Mikkel]

To summarise.

Yes, it matters! Quite a lot.

I'd still go for a too large helmet over no helmet any day of the week though - as long as you bear in mind it doesn't offer the protection it ought to!

[ManDownUnder]

The ladies like my big helmet

Does that make you a piss head?

[Soul.Trader]

I bought a helmet two months ago, and now it doesn't fit. It wobbles around and I constantly have to grab it and push it back into place. Not nice.

Same thing happened to me - does the foam settle after a few weeks? When I first tried it on, it was quite snug - the next size down felt way too tight :angry2:

[James Deuce]

Way too tight is right to start with. The lining does compress. Me 'ead is 59cm Guv. I buy a 58cm helmet, I does.

HJC, Nolan, and Arai give me the best fit. Shark, Shoei, and AGV will not go on my 'ead in a way that could be described as anything other than mega-painful.

[Zoolander]

A new helmet should push your cheeks in and make you do the goldfish expression. The cheek pads shape to your face after a bit of wear and give the helmet a good snug fit. The upper lining should always feel firm but not squeeze your temples in and give you a headache, if so the lids too small. Some people can never get a certain brand to fit right because of the variety of head shapes (i cant wear AGV's for example) so if you're struggling to get the right size, rather than buy a wrong size helmet it would be better to try another brand.

[Soul.Trader]

Damn I wish I'd had some better advice before buying my helmet. I bought a smokey visor with my HJC helmet - if I buy the next size down, is the visor the same size?

[James Deuce]

Yes. Typically there are 2 or 3 outer shell sizes (S,M,L but covering everything from 50cm to 70cm heads) in a range but the aperture for the visor is the same. Size is determined more by the internal lining and pads than the outward physical dimensions of a helmet.

[Shaun]

A new helmet should push your cheeks in and make you do the goldfish expression. The cheek pads shape to your face after a bit of wear and give the helmet a good snug fit. The upper lining should always feel firm but not squeeze your temples in and give you a headache, if so the lids too small. Some people can never get a certain brand to fit right because of the variety of head shapes (i cant wear AGV's for example) so if you're struggling to get the right size, rather than buy a wrong size helmet it would be better to try another brand.




Exellent description

[livee]

Way too tight is right to start with. The lining does compress.

Thankyou Hellzie for starting the query on this or I would not have found it.... & this answer explains my query too! I've had my helmet for prob 9 years now, from my scooter days, so prob explains why when (now that I'm allowed) I get up to 100km it starts to lift! time to go shopping! Yay :woohoo:

[Hellzie]

Thankyou Hellzie for starting the query on this or I would not have found it.... & this answer explains my query too! I've had my helmet for prob 9 years now, from my scooter days, so prob explains why when (now that I'm allowed) I get up to 100km it starts to lift! time to go shopping! Yay :woohoo:

That's ok! Turns out if I had typed in "helmet size" instead of : helmet size
I would have found this thread! Ah well, you live and learn.

I had a helmet that was way too big for me for ages, and only recently got a new one. The dude at the shop (Holeshot) was very helpful and explained the importance of right size. Also, witnessed a seemingly minor crash the other day that has now resulted in the biker passing away due to a brain injury, and I have a sneaky suspicion the size of his helmet had something to do with it.

[nodrog]

Muppets dont need to wear helmets.

Fanny.

[Hellzie]

P.Dath's blog on motorcycle helmets (http://www.kiwibiker.co.nz/forums/entry.php/1562-Choosing-a-Motorcycle-Helmet)

[livee]

P.Dath's blog on motorcycle helmets (http://www.kiwibiker.co.nz/forums/entry.php/1562-Choosing-a-Motorcycle-Helmet)

Good blog! Nice find :D I've armed myself with useful info for when I go shopping!
Hellzie, Are you new to biking or just to Kiwi Biker?? I'm ish-new to biking (4 yrs, not long til I sit my full) but quite new to the forums :)

[Mystic13]

I bought a helmet two months ago, and now it doesn't fit. It wobbles around and I constantly have to grab it and push it back into place. Not nice.

It might be something to do with the 1kg of fat I lost off my head, or whatever, but the thing is, it must fit or it will be very distracting and you don't need this shit while ur riding.

DB

The unspoken rule of buying a helmet.

1/ Get your haircut just before you buy a helmet. Especially if you tend to take off lots.

________

People have mentioned on here about the lining compressing and in my experience some helmets go through more compression than others. I tend to check the lining now and take an educated guess at how much it will compress. You can generally feel the difference in lining from helmet to helmet.

I'm looking forward to the day when they scan your head then produce a lining to insert in the shell for the best fit.

[Hellzie]

Good blog! Nice find :D I've armed myself with useful info for when I go shopping!
Hellzie, Are you new to biking or just to Kiwi Biker?? I'm ish-new to biking (4 yrs, not long til I sit my full) but quite new to the forums :)

Both new to biking and new to KB. :niceone: I've been learning for a few months, but my partner has had a bike on and off for a few years so have been pillion lots. I actually got my learners back in 2005 but only been riding the last few months.

Good luck with sitting your full - you got it booked in? I haven't even started thinking about sitting my restricted.. got a long way to go yet.. hehe

[livee]

Both new to biking and new to KB. :niceone: I've been learning for a few months, but my partner has had a bike on and off for a few years so have been pillion lots. I actually got my learners back in 2005 but only been riding the last few months.

Good luck with sitting your full - you got it booked in? I haven't even started thinking about sitting my restricted.. got a long way to go yet.. hehe

Way to go! Pootle round on your learners as long as it takes! The more you ride, the more confident you will be, and comfortable, sitting the test.

Think it was early 2007 I got my learners, finally sat my restricted in November 2010, can go for the full end of May, will book it closer to the time :) My first bike got stolen so I've future-proofed while I had the financial opportunity and got a slightly bigger bike, so I'll have to borrow a bike to sit the test, new bike will be locked up & rego on hold in the meantime. Gonna be hard not riding until then!