I bike every day in warm months and for some days for hours at a time. Some Saturdays I'll bike 6 hours. The rush I get and the long term affects are fantastic.
I think you'd enjoy it - and your knees thank you.
I run 2-3-4 miles, on M-W-F. More than that, my legs start telling me I’m 54 and pushing 55.
Bicycle the rest. All the gain without the pain.
Try swimming or get ready for weeks of recovery after knee replacements. Seriously.
http://running.competitor.com/2011/08/injuries/the-10-best-mobility-exercises-for-runners_36329
I recommend crossfit training and mobilitywod.com
Mobility WOD is a site offered by a very talented physical therapist who specializes in athletic performance (Kelly Starrett). He is a crossfitter who explains how to rehab common athletic injuries/problems, and how to correct underlying causes like range of motion constraints, strength imbalances, poor form/movement patterns, etc. IT band is a common problem, and rolling it on a foam roller is a common aid to many.
As a guy on the long side of 50 with a string of traumatic and overuse injuries (AIRBORNE!), I was losing a lot of function and conditioning, and experiencing progressively worse pain and early arthritis - until I started crossfit. It is a well rounded strength and conditioning program, along the lines of what olympic and professional athletes do, but geared toward general fitness and scalable to suit even the quite frail. My results have been lifechanging.
Running is so repetitive, that done too much it will eventually overwhelm the recovery capabilty of some body tissue (which declines with age). Rather than running more miles, crossfit emphasizes running shorter sprints (100-200-400-800 meters) mixed with strength and power exercises (including plyometric box jumps which emerged from East block olympic teams to revolutionize track and field training programs). A few 5Ks a year to test/benchmark capability. Cardiovascular endurance, VO2 Max, etc. are built up during constantly varied bouts of powerful functional movements like pull ups, jumps, weight exercises and sprints (on rowers as well as on tracks). Most people significantly improve their run times while running a hell of a lot fewer miles, and gaining impressive athletic physiques, power and speed. Compare how powerfully built sprinters are relative to marathoners. Just relying on distance running for overall fitness is pounding whatever the same weakest link is in your kinetic chain to its limits, while stronger elements are sub-optimized.
By varying the mode and duration of training stimulus you can develop a broad range of capability, and give each more recovery time before you pound the same thing the same way again. Crossfit is pretty time efficient as well - warm-up, hit it hard for 10 or 20 (maybe 30) minutes and hit the showers. There is more to life than just running - train to lift, carry, throw, climb, and jump as well. Be ready for anything.
crossfit.com