I regularly do 50-75mile runs on my Giant Warp DS2 MTB!!

Tightened up the forks, road tyres & Ergon grips, & off I go.

I can't use road bikes because of a lower back problem, but do OK with the DS2. Not aerodynamically great, but can do a 50mile run at about 18mph.

I haven't tried a hybrid, do you think I could improve my times??