When I got my Edge 500 about two months ago, I also ordered the cadence sensor and deluxe HRM separately. Less expensive that way than getting the bundle. First time I used the Garmin HRM, thought it was defective and couldn't see how it unhooked. Silly me ... I "stepped" into the thing and pulled it up over my hips. Only the second time using it did I see how it unhooked. However, I don't like the thing very well. My Bontrager HRM is a lot more accurate and records data a lot sooner than the Garmin HRM. I'd send it back if I could. The Edge 500 records the Bontrager HRM data just fine.