I have a Tiagra triple, 50-39-30 also, except I've replaced the 30T with a 26 tooth. I've lowered gearing further by inserting a 30t in the cassette for very low gearing. Don't need it often but when I do, I'm very glad it is there. Best wishes for the ride and with rehab of the knee. I've brought my downhill ski career to a close before wrecking the knees. Now I play in the snow with cross-country skis and look forward to sliding through through the woods at a much slower speed.