"The CE BACK PROTECTOR standard is labeled EN1621-2. The test is performed with a 5kg “kerbstone” dropped from one meter to create the test impact energy of 50 Joules. The standard contains two levels of force transmission performance. 18kN passes LEVEL 1 "basic" compliance and 9kN passes LEVEL 2 "high performance" compliance. So LEVEL 2 protectors allow 50% less force to reach the spine/ribs."
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"There has been criticism of the standard from medical experts who consider the transmitted force levels too severe; citing decades of automotive research which indicates 4 kN is the maximum force the brittle bones which form the human ribcage can withstand before they fracture. Four kiloNewtons is the requirement adopted in standards covering, for example, horse riders' body protectors and martial arts equipment."
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"Back Protection for Motorcyclists--Only a few motorcyclists receive a direct blow to the spine causing serious injury; more spine injuries are probably due to direct blows to the shoulders and hips. The products commonly known as motorcyclists back protectors, if correctly designed and constructed may alleviate some minor direct impacts on the back, but will not prevent skeletal or neurological injuries to the spine in motorcycle accidents."
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"It appears that most riders’ assumptions about the use and effectiveness of back protection is more than even the highest rated protectors can live-up to in actual performance. This information won’t stop me from purchasing a back protector, but it certainly gives me a better understanding of what to expect at current levels, so as not to be fooled by stories or sales pitches to the contrary."
