I am 44, 160lbs. When I ride at 80% of my HR max, my power output is only 155 - 165 watts.
I guess it is low...
I wonder what other people of my age average at this HR percentage..
I did this test on a powemeter (CycloOps Electronics), on a road this HR gives me
15 - 16 mp/h
If riding 40km time trial at or near LT I can average 19 mp/h
I would guess switching to a road bike (I ride Trek 7.5FX hybrid) maybe give me something,
but I am not sure how much..