Strava is new to the endurance training world. Like many others before it, Strava exists as a tool to aid you in accomplishing new goals and heights in fitness. The reason I love it, is that it works. Many tools you can buy for measuring and gauging fitness are expensive. Power meters, heart rate monitors, gps tracking, it all fits a particular niche and provides you data. But in the most fundamental and raw sense, Strava tells you the truth: how fast you are.
There are close to a million users on Strava. As a result, you're never the fastest person on there and someone will always steal a KOM from you. But the beauty of Strava, is that it has created a way for you to not only directly compare yourself with others, but also against yourself in a measurable, repeatable nature. For a century, cyclists have been going out and doing their "training route" as fast as they can in an effort to best themselves. Tim Krabbe wrote about that in his book The Rider. Strava has simply captured that for you, and given you thousands of new "training routes" to choose from by which to measure your progress.
Every once in a while, I'll go out and hit a few segments hard. I do it to see how I'm improving. I'll look at heart rate and power data if I can, but at the end of the day, the time is the time.
The First Single Track: this is a short and windy single track that I use to see how I'm improving technically. Its 1.6 miles long, no climbing, with lots of places for bursts of power.
I've ridden this section dozens of times. My fastest time is 7:39 with an average heart rate of 170bpm from a ride on 9/21/13. Back in 11/8/12, I did that segment at 170bpm average and went 9:48. So over the course of 10 months, I've managed to find 2 minutes and 10 seconds for the same effort level.
Another segment I go to for longer, more endurance focused efforts is, ironically, the Second Single Track. This one is 3.2 miles with a few rolling hills. My best effort here is 15:03 at 172 bpm from 9/21/13. A similar effort from 3/15/13 at 173 bpm netted me an 18:36. So over 6 months, I've seen 3 and a half minutes of improvement at similar effort levels!
Now, there are many variables that can effect heart rate, and I understand that. But the point is, that Strava has created a fantastic tool that allows for immediate analysis of a given ride against all of your historical data. Admittedly, its value grows the longer you use it, but for the cost, it seems worth it even in the beginning.
So there you have it. I love Strava because it tells me the truth; again and again and again.