Hi All
I am / was a very keen road cyclist and a couple of years ago, before the hip pain got too much, I was averaging 150-200 miles per week. I continued riding a gym bike right up to 3 months before surgery but then transferred onto the cross trainer. In my experience 'serious' cycling in a racing position puts a great deal of strain on the hip flexors and can over-develop the quads at the expense of all the other muscles around the hip. The PT in my local gym pointed this out to me and I got much less OA pain and discomfort when I transferred to on the cross trainer. I also worked on adduction/abduction machines, to balance the muscle development.
I would personally not contemplate going back onto the bike until +10 weeks from surgery, and then taking it easy (which is really hard if you've been keen!!). I am more or less resigned to missing the rest of this year from an outdoor cycling viewpoint, and will let myself in gently in the gym in due course.
Also I raised the 'what happens if I fall off?' question with my surgeon. He said first, he would swear at me, second I'm unlikely to break the new hip but third, I could break my femur - bone tends to break before metal. To be honest, that makes me quite apprehensive about continuing with road cycling. I fell off very heavily 3 years ago at 23 mph on my right hip and shoulder and I'm pretty sure that, more than anything else, was responsible for accelerating the decline in the right hip joint. I'd be very sad to hang up or sell my road bike, but the longevity of my new hip comes first.
Hope that helps.