I went down from 48/19 to 46/19, or, from about 68 to 65, and I made it up the hill. It was hard, but I made it. One thing I notice, though, is that it seems a little harder to slow the bike down when descending with the lower gear, unless I'm going fairly slow to begin with. On the flats, its easier to slow the bike down with the lower gear. But, going downhill I seem to pick up more spinning momentum, which seems to make it a little harder - or at least no easier - to slow down. I'm not sure if I'm imagining this, or its a real phenomenon. Anyway, I think I like the lower gear for now, because of the hills, but I'd like to go back a little higher otherwise.