Originally Posted by
superdex
to answer directly, 3-4mph? Below that, you'll be walking. And it'll be a 22% grade. In other words, the 52/36 and 11-32 is plenty. You could go with a 50/34 up front if you want a little lower, or go with a "mullet" setup which is a mtb derailleur and cassette with road shifters. Considering you're able to put in 225-250 watts, if there aren't other limitations to ditching the e-bike, you'll be fine.
You may be walking. I’m still pedaling. It may seem like a fools errand but pedaling at that speed is easier than walking the bike. My lowest gear is in the 15” range…and, no, I don’t think a 36/32 low is “plenty”. At 60 rpm, that not quite 3mph and I can stay upright down to zero.