If I was towing that much weight, I'd be using the full range of gears. I spend a lot of time in granny gear (which still isn't low enough).
My neighborhood ride is just a 9 mile loop through the subdivision, but has cumulative elevation gain of about 1300 feet. It takes me almost an hour to ride those 9 miles. I need everything from the smallest combination to the biggest. (My max speed last week was 40.1 mph, but for 2.5 miles I didn't get out of granny gear.)
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