A 19T front sprocket with a 42T in the general area where I live would result in a lot of shifting 'tween 4th and 5th gear and inadvertent lugging (not good) of the engine. A combo of 17T-41T (my fav for OEM tires) or 18T-43T is all the taller final ratio I would go in hill or mountain country. I'm not willing to give up the power/torque to the back tire you need for passing SMVs or touring loaded down for a little real or perceived smoothness. But to each their own to suit the topography you may encounter and the load you haul.
