Fuel mileage.
You should have about 2 gallons left when the light comes on, maybe 3 at a stretch. I'd expect about 30 - 40 miles TOPS before you're walking. If it's out on a trail (bad fuel mileage due to driving style required) expect a lot less.
I noticed when I first got my V-Cross that it gets enough better mileage on premium over standard that the extra cost worked out about the same as the cheaper stuff, but it GOES so much better why would you bother with the cheap stuff ?
I have seen 349 miles as the best I ever got out of a tank, and yes the little orange light had been on for awhile, about 15 miles.
That was a special period where I used cruise control a lot, travelled just on the highway to work and back... and obeyed the speed limit. B]
God is a comedian playing to an audience too afraid to laugh.