Chondromalacia patellae & patellar tracking issues due to VMO weakness are, indeed, very common. Unfortunately, it appears to be magnified in the (enthusiast) cycling population. Functionally, the VMO really only "kicks in" for roughly the last 30 deg. of knee extension. When seated, can you guess how much knee extension is "blocked off" at the bottom of each pedal stroke? If your fit & seat height are correct, it should be about 30 degrees. The terminal 30 deg. of knee extension isn't seen much on a properly fitted bike. Obviously, not everyone will have RTC's unfortunate experience, but there are steps you can take to help prevent or correct the "strength imbalance". My favorite are:

1. Short arc quad sets in the form of (body weight) wall squats or (weighted) leg extensions. I prefer the wall squats, but just remember to keep the range of motion small- a 30 deg. arc is pretty short. Return to the start position in a slow & controlled manner.

2. Step-ups & Step-downs are nice because you can do them almost anywhere. When you step up, make a conscious effort to keep "squeezing" the VMO throughout the range. Hold it, still "squeezing", for a 3-count and return to the starting position slowly, still "squeezing" the VMO to control your speed. Relax & repeat.

3. Lunges are a nice way to strengthen the entire quad complex without neglecting the VMO. Just don't do them in public while wearing running shorts. Please.

Naturally, for those not coming back from injury or already possessing a high level of fitness, those exercises may seem quite easy. Those folks just need to be creative in increasing the intensity via more sets/reps, added weight, etc.

As always, YMMV & be sure to see a doc for any chronic or lingering problems.