Typically for me, I need to replace my sneakers anywhere between 250 – 350 miles.  I try to keep a date in my sports software like Endomondo or Gamin.  But sometimes my sneakers tell me it is time to replace them.  When they are getting old, I sometimes feel it in my knees, shins or calves.  Lately I was having calf cramps and then realized I think it was time to replace my sneakers Taking a look at the bottom of my sneakers also tells me when/if it is time for a new pair. When you get a new pair of sneakers, Nike in my case, they have little knobs on the bottom tread.  Those begin to wear down with use.  As you can see, the pair on the left have some good wear on them.  They have about 275 miles on them.   It’s never a good idea to try something new on race day, but I knew that breaking in a new pair of shoes isn’t an issue for me, especially when I am wearing the same brand, so I used my new pair for the Heartbreak Hill Half Marathon on Sunday and got a PR (for a hilly half marathon – a category of my own I made up!)  I won’t say it was because of the shoes, but they do help! How do you know when it is time to get a new pair of sneakers?