I started this thread earlier this week - I might be a flatlander ... - it got me thinking about a challenge: What's your flatest route? I'm gonna say the route should to be roughly 40 miles or more and should be a loop or out-and-back (avoid doing short laps on repeat or a one-way route going down the side of a mountain).

For me, it's the Dakota Trail, it's 50+ miles (out and back) with a total of ~615 ft of climbing, or 12 ft/mile. The Dakota is a paved rail-trail running west of Minneapolis. https://www.strava.com/activities/315912883 I've liked it for constant effort rides, in addition to being flat, there are limited road crossings on the west end of this route.