The Giant site says the cranks are : FSA Gossamer Mega Exo, 34/50 T. So I'd basically be missing the biggest & the smallest gears.

Grade : It looks like an average of 5.5% - up to 6.7% for the hard parts. Not quite sure what this means, but that's what google gave me. Also, the Marin Century has 6250 feet of hills.

I'm far more concerned about finishing than about finishing fast. But it would be nice to be able to keep up with the rest of the girls.