On Google Maps if you choose bicycle routing, it will show a plot of the elevation changes.
330 and 18 climbs from 1000ft to 7000 in about 30 miles, in a what appears to be a steady climb.
18 from the north starts higher, about 3000 ft, but does most of that climb in 15 miles. But then there's the 2000+ ft climb to Cajon Pass.
Years ago when I was in college in Pasadena, I attended a number of retreats around Big Bear. I don't recall the school buses having any problems with the direct route up from San Bernardino, even in the winter.
