We could tell you to replace your seat every 10 years or 100,000 miles, but really (just like running shoes) the best way to tell when to replace your old seat is by comparing your old seat to a new one. Examine your seat for rigidity and shape. All seats wear out, especially seats with cutouts, relief areas and lots of foam, which wear out more quickly since there is less structure and surface to support your body weight. Compare your current seat to a new one at least once a season (unless it’s suffered an impact or a lot of abuse) by assessing it for damage or decreased structural integrity/ loss of padding support. You might not develop knee pain like you might with old shoes, but a comfortable bottom is no less important!