By adding a heart rate monitor, speed sensor, and cadence sensor to the already revolutionary functionality of its newest Edge head unit, Garmin's Edge 520 Bike Computer Bundle comes ready to take advantage of metrics, measurements, and features that aren't supported by any other Garmin Edge model. The direct connectivity with Strava is even more exclusive: the Edge 520 is the first head unit in the industry to interface directly with Strava segments. We like the 510's ability to auto sync with Garmin Connect segments, but let's face it: when it comes to competing for segments, Strava's the real battle ground. The 520's direct connection to Strava gives you an edge in that battle because the segments update live as you ride, simultaneously displaying the stats of your present performance against the current KQOM and your own personal record in order to help you more effectively portion your efforts. In addition to just being a lot of fun, live Strava connectivity also provides more structure to training and race prep by keeping you constantly linked to an external referent, allowing for data parsing and adjustments during the rides themselves, not just in between them. The list of parse able, power related metrics has also expanded compared to the 510, so the data nerds get as much of a win as the Strava junkies. For us, the big star here is that, when paired with Garmin's Vector or Vector 2 power meter pedals, the 520 calculates your functional threshold power FTP. Once equipped with an FTP, you'll be able to calculate ideally timed and measured efforts for intervals tailored to your own fitness level. Instead of burning out trying to hit arbitrary output numbers, knowing your FTP helps you stay at a level that's more effective for increasing your present level of fitness. After all, the real point of intervals isn't punishment it's improving. The Edge 520Vector combo makes that improvement even more efficient. When it's paired with any other ANT compat...