If you're looking to build strength for skiing then I'd be looking at exercise which builds strength; whilst cycling is great for cardiovascular fitness it does very little for strength - particularly given that skiing uses a lot of twisting ranges of motion compared to cycling.
I'd suggest firstly starting with 1 session with a well-recommended sports physio - ideally one who specialises in skiing and/or running; they should be able to guide you as to what strengthening exercises will work for you given the previous surgery.
Then I'd do some sessions with an expert in free weights; for skiing I'd be thinking that squats, lunges, step-ups with a barbell would be the right kind of thing,i.e., whole body exercises. There's a decent body of evidence that strength training reduces the risk of injury.
Finally, I'd be looking to do some trail running / fell running.
None of the above will hurt the cycling (although arguably none of it will improve it much either) - For the cycling I'd suggest looking at the British Cycling (BC) plans;
https://www.britishcycling.org.uk/knowledge/training-plans probably the improver's plan. Your cadence seems very low and the BC plans tend to have a lot of cadence work in - most of them include being at 90+ for most rides with some of the cadence drills pushing 100 - 130rpm (although all at fairly low power zones) - whilst there are some people whose cadence is naturally quite low; most people are more efficient between 90-100rpm. So I'd be inclined to experiment with a much higher cadence for a few weeks; if it doesn't suite you can always go back to what you were doing.
