Austinite in Conroe — where can I ride 20–25 smooth road miles Saturday morning?

I’m an Austinite in Conroe for the weekend, and I need to squeeze in 20–25 miles tomorrow morning.

Does anyone have suggestions within about a 20-minute drive of downtown Conroe? I’m trying to avoid gravel and big bumps, so the smoother the route, the better. I’d love any local insight.