Originally Posted by Mr_Super_Socks
a few ways:
someone tells you who has measured the route (i.e. for events or well travelled routes);
you use an inclinometer which gives you the grade right at the spot you are standing;
you see a road sign that warns you of an impending 10% grade and you pee yourself cuz you're toting 100lbs of crap on a tour through italy . . .
One more. Call your local Public Works or state transportation department.
How tough is it to change a flat on a Nexus equipped bike? I've had an Electra Sunny Garcia for a couple of years and haven't had a flat yet. I guess I should give it a close look one of these days.