My commute is 7.5 miles up and down hilly areas. I seem to go around 5-8mph up some extreme hills, but won't come down very fast; I guess that can be improved. Still, my flat ground speed and my speed off the road isn't great either.

What's the nominal for an 8 mile commute? I'm trying to do it bike-to-check-in in under 40 minutes--my time in the car when speeding (43 minutes when not speeding, why bother) car-to-check-in. Mind you in the car the parking is a third of a mile away, down a hill I have to walk up; the bike goes up in under one minute.

My cadence is pretty low, by the way, probably around 60 or 50 usually. I've seen mention of what appears to be using an exercise bike to improve that, but I'd rather stick to transportation for bike use; maybe I can use the high resistance on the mountain paths for a purpose (they're relatively flat and a mile or two long). Would an upgraded bike computer with a cadence monitor be a worthy upgrade if I'm trying to target this particularly? I think stamina may be an issue in any case.