Are there any proof that a $300 helmet would provide twice the protection level as a $150 helmet? or what about a $600 helmet? Would it provide 4x the protection or guaranteed at least 4x better impact resistant? :D

Just wondering...

No.

Ok well this may be lengthy..

My personal opinion is no. Other people have a different opinion but this one is mine. Bottom line is if you are only riding on the street then all you need is a DOT helmet. If it has a DOT sticker it meets spec. So basically I don't care if you $20 for a helmet if it's DOT and it feels good on your head then it's a good helmet.. I have lots of helmets ranging Z2R to Icon. My favorite is my scorpion not because it was $300 helmet but because it feel comfy and flows air well. I also have a Icon that I paid close to $400 dollars for and I think it's the biggest pile of sh!t I own.
Ok now my wife just picked up a 7zero7 not to long ago and they are inexpensive and IMO very well put together. It's comfy and she loves it. It is DOT and SNELL rated all for like $140 bucks.

My HJC helmet that retails for $100ish is DOT approved. My Scorpion helmet was closer to $200 and is DOT and Snell approved. The price difference comes from build quality (materials used, shell composition, durability). Price doesn't indicate inherent crash performance. A caveat though: manufacturers pay the Snell foundation to test their helmets to get Snell approval and this cost is passed on to the consumer in the price to some degree.

My 2 SparX helmets were $100 a piece and are DOT and ECE approved. ECE being European equivalent to USA's Snell rating.

/moved to motorcycle gear

http://midliferider.com/blog/2008/03/24/whats-the-best-helmet-treading-bravely-across-a-minefield-of-personal-preference/

Kind of a long read, but worth while I think.

Fit is THE most important thing and trumps ALL other considerations. A helmet should fit like your scalp. You should not be able to move it around easily. You don't want your noggin bouncing around in there.

It should press on your cheeks. Look at close-up photos of auto and bike racers. See how their face is squished a bit? There's a reason for that.

At the same time, it should be completely comfortable. No pressure points.

Different helmets have different shapes inside. Some brands will not fit your head... they'll be too big side-to-side or front-to-rear. You simply have to try a bunch on. I went to the local dealership and tried on half a dozen helmets. I did buy something while I was there to be a good citizen, but I bought my helmet online.

Webbikeworld.com has a vast amount of information about helmets.

My head happens to fit inside a Joe Rocket RKT101 as if the helmet was custom-made for me. And I got a closeout for only $110 or so. It's DOT AND Snell approved. You can get GREAT deals if you go with closeouts. New Enough has the carbon version of my helmet right now for under $150, which is a steal.

Speaking of standards... they're controversial. It is a complex subject. There are those of the opinion that building a helmet to meet certain standards actually reduces its effectiveness. I don't really buy that because I understand the complex nature of the issue... you can design tests to prove points in a certain way. How that translates to the real world is a different issue. Google is your friend if you want to learn more.

Most of what a helmet is going to do in a real-world crash is protect you from abrasion. And most of the damage is going to take place on the front and sides. Look at photos of crashed helmets and this is obvious. Lesson: Full face only, thanks.

Another thing to consider is the availability of shields. Your shield is going to get scratched before the helmet wears out, and you may want to get a tinted shield to supplement the clear one that the helmet will come with. Good luck finding a shield for some no-name brand. My Rocket was made by HJC, so shields are easy to find.

Also take a look at how the shield fastens. I had an old Nolan years ago that was a real pain. My new helmet is great.

CLICK HERE FOR A GOOD READ ON HELMET TESTING/some science involved!!! (http://www.motorcyclistonline.com/gearbox/motorcycle_helmet_review/index.html)

As another interesting note, the current crop of carbon helmets DO have a shelf and service life! While not talked about much, the plastic shell helmets have a service life, too. Esposure to UV rays from the sun breaks down the chemicals that act as binders in the resin that holds carbon fiber helmets together.

UV also leaches the elasticizers from polycarbonates, which is why plastic parts get brittle over time. The same applies for the plastic shells and foam padding in our helmets.

If you've ever had the misfortune to test a helmet, you will find that there is a big difference between good and absolute trash.

There isnt a half face helmet on this planet that is worth diddly in a crash. At the most they will keep your hair on, but that's not much comfort when your jaw is crushed and you need reconstructive surgery to piece your chin back together. You will never see a track racer wearing such garbage, and they've been banned in motorsport racing for this very reason.

As far as the full face helmets go...not all are created equal. And its not just in how much protection they offer. There are a lot of other factors too.

The real key is getting a helmet that fits properly. A loose helmet will feel like it wants to lift off your head at highway speeds. Poor quality results in whistling, or wind noise. If the vents are lousy, it gets hot. If the padding is shoddy it can leave pressure points that will give you headaches.

And of course, no helmet is good unless its on your head.

I don't know why I feel the need to comment.. as most of this has been covered by folks who know more about it than me already.
but some helmets are better than others.

Materials and design can make a difference in a crash. Also they can make a difference in wind noise and airflow.
(what's better I have no clue as I don't crash helmets for a living)

I think every helmet has an expiration date.. Get a new one if you even think you need a new one. I think it's the single most important piece of gear we ride with.

That said, make sure it fits you well, and you like it. Most important.
It has to fit snug as everyone else already said.

If you feel it's made of funky/cheap materials, save up a few more bucks and go with your gut instinct. It can never hurt to put more $$$ into better materials on your helmet.

While in the shop, I still felt CF helmets were much more flimsy than a basic painted shoei. (trsut me I wanted to buy a spiffy carbon fiber helmet to look good on me) You can actually squeeze the sides of the helmets and flex them a bit. I went with the less flexible helmet. (Shoei Rf1100) It feels like a solid bowling ball. Size medium fit my huge head perfectly and snug. If I move my chin left and right (grind my teeth left and right), helmet does too.
It is hard to get in and out of when I put it on or remove it.

Wind noise, airflow and comfort are all changed (for the most part) for the better with a nicer helmet. Certain head shapes fit well into certain brands of lids. I see this question with bicycle (non-full face) helmets all the time-the $30 helmet provides the same protection as the $350 helmet, but it weighs 3 times more and has half the ventilation.

Not hot:

http://cdn2.ioffer.com/img/item/114/347/472/0wb0.jpg


Hot:

http://www.trialtir-usa.com/las/supreme/images/supreme-anthracite-lar.jpg

Fit is THE most important thing and trumps ALL other considerations.

I totally agree.

If it is't comfy you WILL regret it.

The two things I look for in a helmet are #1 Fit and #2 Ventilation. (Along with the DOT / Snell sticker)

I actually like my KBC V2R better than the Shoei TZR helmet I also own. KBC is a Fiberglass shell and was about $100.00 cheaper than the Shoei which is a poly shell (KBC was lighter and has a better aero profile from my experience).

Im sure either one will hold up fine in a crash but I was surprised by the quality and fit of the KBC other than its a tad noisier.

but I just want it so bad!

http://www.grandprixlegends.com/Images/Products/Large_Images/XLT940_1.jpg

+1 for fit
my cousin got t-boned while riding and his injury was a broken jaw due to the helmet being a tad loose, he had given his helmet to my other cousin which was the passenger and she walked away with a mild concussion. ever since then i make sure that my helmet is nice and snug regardless of the price.