He ran some DOT impact certification tests on some 10+ year old helmets and they passed tests to the standards they were built to with no problem.
The polystyrene may shrink a bit but I've never seen old Styrofoam significantly degrade unless left in the direct sun day in and day out. I understand Brent's POV, just not sold that it degrades significantly in 10 years if care is taken to not expose the helmet to persistent heat or sunlight.
I think helmet fitment is a better rationale to change it out. Or when the fashion starts looking dorky.
I remember reading an article in one of the moto magazines about five years ago either written by, or referencing, James Ouellet who was one of the authors of the original Hurt report and is now the president of Motorcycle Accident Analysis Inc. He said that the five year life of a helmet is not necessarily true. He said that if the shell is intact (hasn't been dropped and has no visible cracks) and the chin strap is still properly attached and not weakened, the helmet still has plenty of life left in it. He ran some DOT impact certification tests on some 10+ year old helmets and they passed tests to the standards they were built to with no problem.Sorry but I can't produce the actual article.I still replace my helmets about every five years anyhow as the chin strap is usually pretty frayed and even if I haven't dropped the helmet it's still been banged around enough that I figure that I need to get a new one.Dale B
Quote from: pkpk on April 04, 2013, 04:12:38 PMThe polystyrene may shrink a bit but I've never seen old Styrofoam significantly degrade unless left in the direct sun day in and day out. I understand Brent's POV, just not sold that it degrades significantly in 10 years if care is taken to not expose the helmet to persistent heat or sunlight. I've never measured the degradation of polystyrene in any objective way, so I can only guess, but if it shrinks, then it has become more dense and therefore less protective. (Unless some of its mass has evaporated or something. I really don't know why it would shrink other than from being pressed between the shell and the rider's head.)Quote from: pkpk on April 04, 2013, 04:12:38 PMI think helmet fitment is a better rationale to change it out. Or when the fashion starts looking dorky.Or when the Snell standard changes. M2010 was a significant change from M2005. Otherwise, I think Dale's rationale of a frayed chin strap is as as good as any.