I am 6'1" 240, my wife is 5'2" 110lbs - she has no problem keeping up with me on the flats as long as I don't put the hammer down. Sometimes she can out-climb me, sometimes she can't. On downhills I pretty much have to wait for her...even coasting. Gravity is a wonderful thing for us big guys going down...not so much going up.
those 8 gears on her bike will cover pretty much the same range as your 27, just not as granular (bigger jumps in between gears), but if you are going to be doing a wider variety of rides you might want to ensure her bike is geared similar to yours.
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"Let us hope our weapons are never needed --but do not forget what the common people knew when they demanded the Bill of Rights: An armed citizenry is the first defense, the best defense, and the final defense against tyranny. If guns are outlawed, only the government will have guns. Only the police, the secret police, the military, the hired servants of our rulers. Only the government -- and a few outlaws. I intend to be among the outlaws" - Edward Abbey