I ask because I just got a POC Tectal to replace the Trebec I've had since '14.  Nice helmet!  Mounted the mirror, then started reading the instructions.  Of interest - when do I replace it.  Well, and I quote "It is recommended to replace the helmet every tree years at least."

If a tree year is like a dog year, this could get expensive.  The Doug Firs in my front yard are probably good for 2-300 years.  So 90 years ( human life expectancy) / 300 = 0.3 "tree" years or a little under 4 months.

And a little more serious - the Trabec I am replacing is the best helmet I've had by far.  It has held up very well.  I have not repaired or replaced anything, even pads.  I do use a skull cap always as I have for the past several helmets.  Leave the house wearing a clean one.  I haven't tested either it's impact behavior or the MIPS, but comfort-wise it simply disappears.  And that is despite the considerably more coverage and weight than any recent helmet I've worn.  (My old Bell Biker was probably the Trabec's weight or more.)  Trabec - 357g.  This Tectal is 37g heavier with the mirror mounted so I'm guessing 10-30g lighter.

So here's hoping this new one is just as comfortable and it has a life just as boring.