Admittedly, I've got a decade plus of racing experience, but unless you're talking residential streets with lots of cross traffic, 12% isn't THAT steep. I routinely ride up and down 15+% hills around here, usually topping 40mph and occasionally 50+. The main thing is to relax, have confidence in your equipment and skills, and focus WAY ahead. Keep your hands near the brake levers, just in case.

Not everybody has as high a "zoom factor" as I do, but it behooves you to develop your skills and confidence to the point where you can handle whatever road conditions you find. I'm not talking machismo, but safety.

SP
Bend, OR
...and yes, I like to get my "gravity's worth", but I won't go (too far) beyond my skill level.