bike skateboard helmet Two Removable Liners Ventilation Multi-Sport Youth Adults

Product Specification

bike skateboard helmet Two Removable Liners Ventilation Multi-Sport Youth Adults​   ​   

DETAILS:

INFORMATION:

Thicker foam is better, giving your head more room and milliseconds to stop.

If the foam is 15mm thick it obviously has to stop you in half the distance of a 30mm thick foam. Basic laws of physics result in more force to the brain if the stopping distance is shorter, whatever the "miracle" foam may be. Less dense foam can be better as well, since it can crush in a lesser impact, but it has to be thicker in order to avoid crushing down and "bottoming out" in a harder impact. The ideal "rate sensitive" foam would tune itself for the impact, stiffening up for a hard one and yielding more in a more moderate hit.

If the helmet is very thick, the outer circumference of the head is in effect extended. If the helmet then does not skid on the crash surface, that will wrench the head more, contributing to strain on the neck and possibly to rotational forces on the brain. In short, there are always tradeoffs, and a super-thick helmet will probably not be optimal. It will also fail on consumer acceptance.

If there are squishy fitting pads inside the helmet they are there for comfort, not impact. The impact is so hard and sharp that squishy foam just bottoms out immediately. In most helmets a smooth plastic skin holds the helmet's foam together as it crushes and helps it skid easily on the crash surface, rather than jerking your head to a stop. In activities that involve forward speed on rough pavement, rounder helmets are safer, since they skid more easily. The straps keep the helmet on your head during the crash sequence. A helmet must fit well and be level on your head for the whole head to remain covered after that first impact.

Helmets designed for lesser impacts do not necessarily have foam inside. Some are just hard shells with a suspension headband that provides the fit and keeps some space inside for air to circulate. Construction helmets are of this type, and do a fine job when somebody drops a brick on your head or you bump hard against an overhanging steel beam. Just don't fall off a bicycle with one, since they will not handle the impact of falling on pavement.

The foams in some helmets are crushable but do not ever recover. If you crash a bike helmet made with the usual expanded polystyrene foam, the foam is trashed and you can't use it again. If the helmet is made for hockey or skateboarding it has a slow-rebound squishy foam called butyl nitrate foam, or perhaps expanded polypropylene foam. Either will recover slowly after a blow and can be reused. Construction helmets are ok as long as the shell is not cracked and the suspension is not damaged.

Different types of helmets seem indistinguishable to most consumers, and you can't test the impact protection unless you have a lab and are willing to destroy the helmet. So the industry uses standards to designate performance levels.

What are helmet standards?

Standards define laboratory tests for helmets that are matched to the use intended. If a helmet can pass the tests for a sport or activity, it provides adequate impact protection. A construction helmet will not pass the more severe bicycle helmet tests. A bicycle helmet will not pass the more severe motorcycle helmet tests. None of them provides the protection against shrapnel that is required of a military helmet.
Standards also define other tests for such parameters as strap strength, shell configuration, visor attachments, and the head coverage that must be provided, depending on the activity.

Standards are developed and published by various standards-setting organizations. We work with ASTM, the American Society for Testing and Materials, an organization that publishes a wide range of sports helmet standards. Helmets for US football must meet the standard of the National Operating Committee for Sports and Athletic Equipment (NOCSAE). The American National Standards Institute (ANSI) was formerly active in publishing helmet standards, but is less so today. There are military specifications for helmets for infantry, pilots and lots of others.

There is a NASA standard for astronaut helmets. There are standards from a number of sports organizations for helmets related to their sport. And there are standards for other countries, including European CEN standards and those from Australia/New Zealand, Canada, Japan and others.

A typical standard specifies impact tests, strap tests, characteristics of materials to be used, required coverage, labeling and other requirements. Some have tests to simulate low temperature performance, hot performance, wet performance and sunlight ageing. Test equipment is described as well as the severity of the testing. For a look at a complete helmet standard, check out the Snell Memorial Foundation site, where their standards are all available. Or you can read the US CPSC bicycle helmet standard, probably the most-used standard in the world. For a look at a point-by-point comparison of bicycle helmet standards, check out our short comparison or our more detailed long comparison.

FAQ:

Q: How should I submit artwork and what format?

A: You can submit artwork to us by Email or upload your artwork to our FTP.

We accept: COREL DRAW, ILLUSTRATOR, COREL PHOTO PAINT, PHOTOSHOP,

TIFF,. JPEG,. GIF (tiff at 300dpi, jpeg at 300dpi, gif at 600dpi 100%size)

PDF (vectors in PDF, if using raster program make sure you have high res at 100%size.)

Q: What are setup costs?

A: Set up costs most often apply to new graphics. The first time you order and have a two color print to it, we charge a one time

fee for two screen charges. If you are an existing customer and you want to a NEW graphic the same rules apply. Set up fee for

normal deck heat transfer graphic: USD160 unlimited colors. For longboard transferr graphic USD320 unlimited colors.

Q: Can I order samples?

A: Absolutely, we send requested samples at a minimum charge. You will have to pay shipping cost and samples fee,

the samples fee will return back to you after you place your order. New customers must email us the following information.

Company or shop name, Address, telephone No. specific boards.

Q:When is your delivery time?

A:It depends on product and order QTY.

Normally,it takes us 25 days after receiving the deposit,Repeat order only need 15-20 days.

Q: What is the loading port?

A: Regularlly Ningbo or Shanghai

Q: Do you provide OEM developing services?

A: Yes,we have plenty experience in OEM developing, aslo for famous brands,