My son bought me the Nike+ sensor for ipod for Christmas. I am wondering if any of you have used this and what you think of it. I calibrated it today so haven't used it properly yet. My biggest challenge appears to be how to attach it to my running shoes. It is made for Nike + shoes where the sensor fits into the sole of the shoe My shoes are not Nike + and have velcro fastenings. I tied the sensor case onto the straps and it fell off near the end of the run Any suggestions? Yes, I know, get Nike + shoes, but I would rather the ones I have.