On Monday, August 5, 2019 at 8:41:29 PM UTC-4, Andre Jute wrote:
On Monday, August 5, 2019 at 9:29:26 PM UTC+1, Tom Kunich wrote:
On Monday, August 5, 2019 at 1:33:00 AM UTC-7, Andre Jute wrote:

Somebody on my ride was saying only the other day that crashes at our age are so much more consequential. Though they were talking about breaking a hip, I thought of that when a couple of days later I fell while dismounting from my bike (I hooked the mixte bar between my foot and its heel) and landed so heavily that the deep dent in my helmet looks like the most dangerous accident I've had in 30 years of cycling -- from a standstill! The helmet saved me from a gash on the head, painful stitches, and perhaps even a concussion. That's definitely worth its price.

Andre Jute
Not an old crock

Modern safety helmets reduce concussions not by softening the blow via cushioning with the Styrofoam but by fracturing and breaking via the "vent" holes in the helmet. I have a Bontrager Wavecell helmet and it has a lot less vents for two reasons - 1. Unlike Styrofoam air passes rather freely though the open core material and 2. you have to have the Wavecell material covering most of your head to have the expected effect.

So my helmet isn't wrecked by the impact-dent?

Separate question. That helmet is actually pretty old, being on its third bike. Is there a natural raging process (embrittling?) of helmet materials that requires helmets to be replaced after x time?

Andre Jute

I think that aging of the foam in a helmet depends on t he foam material itself plus incidentals such as exposure to sunlight (UVA/UVB rays)bumps it has suffered and even exposure to sweat. I have an old hard-shell Vetta helmet here that appears to be in mint condition. I guess it'd take a microscopic examination of the underlying foam section to tell if the foam has deteriorated.

Manufacturers like to sell helmets and also protect themselves from litigation and thus many helmet manufacturers tell customers to replace the helmet every five years or some other number of years and also to replace the helmet if it has suffered a hard knock or fall.

Cheers