Hi Rob39, the blue trail is quite easy but have you put your seat high enough, I know a lot of MTB use requires the seat to be low but on non technical routes set it like a road bike, you could also be using your knees as shock absorbers which is new to them. The final thing is gear chioce, on the Mtb you have to be lightning fast getting the right gear otherwise you can find yourself grinding up a hill in the wrong cog. If you're local try the Glentrool big country run, it's about 36miles but all on forest roads so gradient changes a bit slower with some nice climbs around Loch Dee and Black Loch. I am mainly a road cyclist but do that route to strengthen legs. If your around the Newton Stewart area give me a shout and I will go round the big country route with you. Small adjustments to the bike and practice should fix you.