How long will unworn running shoes last?

I finally found some running shoes I really like, which of course means the company discontinued them. They are still available on clearance, so I can buy some extra pairs now.

How long will they last stored in a cool, dry, dark closet before the soles start to break down (or something else happens)? I usually get 400-500 miles out of my shoes, which is probably about 6-10 months. How many extra pairs should I get? Opinions and anecdotes welcome.

I loved Adidas Osweegos for running and bought a second pair at a BOGO sale, promptly forgetting I had the second pair which sat in the back of my linen closet, still in their box, until 8 years later. They seemed fine at first, but I did notice that they didn’t last as long as my running shoes usually did. I noticed deterioration at about month 4 when I usually didn’t see it until about month 6 or 7. That was really the only issue I had with them.

I’ve always heard that the foams used for cushioning break down over time regardless of how well you store them. Certainly, direct UV rays will accelerate the process, but you can’t keep them too long without compromising the materials. I’ve stored a pair for about a year without noticing any significant change in wear. What I’ve seen online seems to indicate that this was a concern to some degree in the past, but less of a concern today. I wouldn’t hesitate to store shoes for up to 2 years. Beyond that I think you’re in less clear water.

Thanks, I was thinking a year or two as well.

The article you linked to was 13 years old…I wonder if foam technology has continued to improve since then or if the materials have gotten cheaper. Oh well, the shoes are now half price, so still a good deal even if they last only half as long.