I couldn't get OSMA to work. I may not have been on the right website. Can someone please supply a link?
For grade off-road, I am still liking mtbproject. Also, most trails I would want to ride are marked easy, intermediate, advanced-intermediate, which helps. If there are trail that are unrated, it often means they are not suitable for bikes.
Grade is very important to me. Even though I'm in Los Angeles, some of the places I ride are not frequently traveled, and it does seem possible to get stranded in a spot where it would be very difficult to go up or go down. On one hill (fortunately, near my house and I know it very well), I can ride up, but literally could not possibly ride down. I have ridden up only once without stopping, but typically I bonk at the last turn, and have to push the bike up the last 50-75 feet.
Last night, I scoped the entrance to the Las Flores trail in Glendale. It was exactly as mtbproject had said it would be in terms of difficulty. The nasty part was just finding a route there that was scenic, on winding canyon roads, but not too steep-- I don't want to burn too many electrons until I'm on the trail. Canyon roads are sometimes NOT marked on the street the way they are on the map! ("Oh, I thought I was supposed to make a right at Oak Ridge Road, but actually, the right turn is still named for the street I'm on, and it only turns into Oak Ridge Road a couple of blocks later.")
My goal for yesterday was to make sure I didn't have to lift my bike over the gate and explore a few miles of this trail. The wrong turns delayed me so much, and navigation was so slow, that I reached the gate 10 minutes after sunset, at least a half hour later than I'd hoped. But the gate was no problem, and I road about a mile in anyway just to catch the view at dusk = stunning.
And I know how to get back from the gate, which is important: The grade is basically flat most of the way home, I can rip along in ECO at 15-16 MPH hardly burning any juice. I could be at about 1.5 out of 5 bars and still have enough power to get home and make it up the last hill before my house. So I'm pretty sure I should be able to ride the entire spine of the Verdugos on one charge, which will probably involve about 4,500 feet of vertical and about 40 miles.
It will be weird being 18-20 miles from home and having only 30% power left, but it's almost all downhill or flat for the return. Probably will be too hot to do it until the fall, but I'll be keeping my eye open for a good day.