Welcome Cyclic...I'm new here myself. 85% of max sounds pretty good to me. One of the better things to look for how fast your heart rate drops after you stop. Check it after a hard section and wait one minute and check it again. I forget the percentage that its supposed to drop. One of the better indicators is how you feel the day after. If your really tired and groggy you might have pushed it too much.

keep on ridin"!