I mix all three, bike, run, weights, but biking is my main goal so I make sure my legs are fresh for my two important bike workouts:
*Monday-upper body weights
*Tuesday-VO2max efforts on the bike (important workout)
*Wednesday-easy 3 to 4 mile run followed by deadlifts and squats
*Thursday-easy zone 2 bike workout
*Friday-upper body weights
*Saturday-bike threshold workout or spirited group ride (important workout)
*Sunday-easy 3 to 4 mile run followed by deadlifts and squats.
All this equals 3 bikes, 2 runs, and 2 strength training session(muscle group) per week.