If the MTB is going to have an urban life, its original gearing is inappropriate anyhow. It's too low and the upper ring shift is right in the cruise range. The 3:1 range of the cassette seems like plenty for the street if matched to the right ring. And front shifting is finicky.
__________________
Genesis 49:16-17
"Well, well!" said Holmes, impatiently. "A good cyclist does not need a high road. The moor is intersected with paths and the moon is at the full."