Have you heard of the mino? It's a new device that was designed to measure compressions in your shoe to provide for worry-free running. This little insert is placed in the heel of your gym shoe under your sockliner or custom orthotic (and a spacer is placed in the other shoe) and measures your mileage by compressions. There are LED's that light up to indicate when the shoe is safe for running, when you need to start looking for new shoes, and when your shoes are worn out to a point that could lead to injury.
The general rule of thumb is that shoes should be replaced between 300 and 500 miles. The mino was designed to have the last LED light up when you hit the 400 mile mark. This could prove to be a great tool in preventing injuries related to over-worn shoes.
This little device measures in at 2" wide, 4" long and approximately 2.5mm thick. This means that it can fit into a wide range of shoe sizes and even be used in kids' shoes (though sometimes foot growth will determine need for new shoes over the wear of the shoe itself).
This device is designed for one-time use and the company relates that this is to keep production cost down. This is a great investment to protect against timely and costly injuries related to shoes which have lost their integrity.
Give them a try and tell us what you think!