Nicely done! I use Komoot and RidewithGPS, but this is a nice tool if you want to plan a route that relies on bike trails as much as possible.

Would be cool to also show the elevation for a given segment along with its distance (in the route trail list).

And maybe when you click on a segment in the map, it should highlight that segment in the trial list so you see the length of that segment.

I realize you're just using existing map data, but some bike routes seem to be broken up with very small (couple km) gaps (shown in grey) -- is that really the case? (see Loire a Velo 4 for example)