Segment Search Criteria for Length and Elevation Gain
I like to vary my running routes a lot. When planning for a long run I sometimes use Strava segment explorer or activity search for an idea. One thing that I started to realize that longer segments have almost no chance to be discovered. Naturally shorter segments have much higher chance to be matched so longer segments quickly go off the radar. The only way to see them is to search for activities that are longer than say 10 miles and then look for segments within the activities.
Here a simple solution that might be effective. Just like there is a selector for the segment terrain type (e.g. flat, hilly, etc) there might be another segment for the segment size e.g. short, medium, long. If you implement this please consider the elevation gain as a parameter in determining the segment size. Something like the formula used sometimes in Europe that makes 100 meters of vertical gain equivalent to 1 flat kilometer. This would better represent the effort rather than just the distance.
Since I mentioned the vertical gain above I also wanted to mention that the average grade used to determine whether a segment is flat or hilly doesn't make much sense for running. A segment might include multiple climbs and descents and Strava would show it as having 0 degree average grade. A much better metric is total elevation gain/change or perhaps an average elevation gain/change per mile or km.