My gadget geek side found a neat way to interface with Strava (using CycleMeter on my iPhone), and my Garmin Edge 800, with speed/cadence sensor and HR monitor.
I bought a RFLKT+ (Wahoo Fitness), which acts as a readout for the iPhone, so the phone can stay in the handlebar bag, and actually bridges the Ant+ data from my Garmin sensors with the Phone by BT.
I could have bought an Ant+ dongle for the phone and a waterproof phone holder, but I like the clearly readable LCD screen on the RFLKT+ device and the large readout, etc. Also, any dongle purchased for my iPhone 4S would be obsolete for my next phone (thanks, Apple!
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The RFLKT+ runs on a small button battery which is meant to last over a year with daily use. I had some issues with it early on refusing to automatically shut off and running down the battery, but a firmware update appears to have sorted out the problem.
I still carry a Cateye speedo, which backs up my other devices and maintains the true odometer for the bike (front wheel sensor). Tragic, huh?
I'll post a picture of the setup ASAP.