I have both the Wahoo blue tooth heart rate monitor and the speed and cadence sensor. I have an Iphone 5 and use an Otterbox Defender case. I took the holster that comes with the Otterbox and used two zip ties to secure it to the stem. Works perfect and looks good. I have an external battery pack that I keep in a pack that is mounted on the top tube behind the stem. Makes everything very easy. Pop the phone in the mount, plug it in and I am off.