YBeecher:
Welcome to the forums. I had a THR 13 years ago and do not have any issues riding my bike, just hit 3,100 miles for the year. I also worked as a firefighter for 9 years after the surgery.
Best advice I received is follow the physical therapists plan for your recovery and don't push yourself too hard.
Wishing you well on the surgery, I'm glad I had mine at the relatively young age of 45. The physical limits and pain I had prior to surgery had a major negative impact on my life. The THR greatly improved my quality of life.