On my road bike I run a 39-53 crankset and a 11-20 straight-block in the back. Even so comming down Highway 9 from Skyline I find my self compleetly spun out some of the time. Their is no way I would ever loose that big ring. (LOL, for thoes of you that know that decent.)
Geez, how fast are you going? I was not spun out on my 50/34 12/28 coming down Hwy 9. I guess I tend toward the cowardly. To me, it is about 100 times more important to have gears that can get me up to Skyline without mashing, than it is to not have tall gears that are needed for a few seconds of 45 mph instead of 35 mph.