dunno bout the mountain elevation , but we running two hawks w 16/45 and seems to me (ymmv) about optimal at around1k elevation, start right up with a touch of choke depending on temp, run strong, 5th pulls fine. our median main road speed is a tad over 60, secondary road easy 45- 55. one bike's chain turned to silly string at about 650 km. the other, (mine

is holding up like a champ. (the walmart dupont chain spray before any substantial travel returning its usual benefits.) most riding is a 20-30 minute secondary road sprint then some hours of trail grinding at low speed.