Btw-nice pic, cofty. Looks like you have some nice places to ride.
@noonehome- as cofty said, seat postion and proper fit can be critical. With myself, I'm 6'4" and for me there's a lot of prescribed notions of bike fit that get thrown out the window. I usually need a bike that would be considered much too small and then have the seatpost at around the maximum height. I have seen people that need custom made frames as stock sixes just don't fit. If you need the seat slid back or forward, that changes the cockpit room which might require a shorter or longer stem. I'd recommend having someone who knows what they're talking about to look at your fit.
Also as cofty said, keeping a higher rpm helps your legs out a lot. Racers will spend the early season spinning in lower gears for over a thousand miles before they start pushing the higher gears. I'd try doing a bunch of 15-20km rides at a higher rpm, easier pace to get your legs used to that before going longer distances.