This question is related to my search for a road bike. I currently use a mountain bike these past few years.

Where I live, I am bounded by a river to the south and hills to the north. I can’t avoid the hills if I need to get anywhere. If I can climb up these hills on my mountain bike using a gear of 28T front (granny) and 19T rear, will I be okay on a road bike with a regular crank (54/39), or do I need a compact crank (50/34) or maybe even a triple? Is there some mathematical calculation about gearing that says such-and-such gear on mountain bike is equivalent to such-and-such gear on a road bike?

I just hate the thought of bringing home a road bike I can’t climb up with! I’ll never be able to get out of the house!! On the other hand, I don’t want to purchase gears I’m never going to use…