40 miles is the maximum possible with the EXR, when I ride a relaxed Endurotour along a river with a 20-30mph average an grass, gravel and sandy trails at 20 °C temperature.
Same with my '18 MXR, and that is really milking it, last few miles wondering if its going to get me home.
I was pretty disappointed to get about 26 miles up in the mountains, I probably could have gotten 30 or so out of it, but didn't want to run out of juice and have to walk miles back to my truck. I was hoping to get 30 - 35 worry free miles out of it in the mountains, but if its only going to be 25 miles or so, I don't think it will work for what I had in mind.
At this point I'm considering it a training bike that I can rip on locally, its not really worth it to me to haul it an hour or two up into the mountains and start having range anxiety at around 20 miles.
I may give it another try or two next summer, but I'm not optimistic. Its a shame, its really close to being a killer mountain trail bike.