45% incline? As measured how?* Where did you get such numbers? There are few cars capable of going up a hill that steep. In any case, if this is what you intend to ride you need to be concerned with only one thing: Lowest gear. No, make that two things. Lowest gear and your conditioning.. No, make that three, lowest gear, your legs, and your aerobic capacity.

* - I don't know what an "official" definition of this is. When people say this they could mean elevation gained per total distance travelled or elevation gained per horizontal distance travelled. Either way, that' steeeeep, more like a steep hiking trail than a road.