This probably won't help much of you , but here's how I warm up before any exercise.
I stretch, then I preform kata.
for those who don't know what kata is, its a set of predetermined martial arts techniques. Some say its a mock fight between imaginary assailants, but I consider it a movement and focus drill.
I start with a kata called Heian Shodan (Peaceful mind #1) and go through to Heian godan (peaceful mind #5), then I do tekki shodan (iron horse # 1). By that time, i'm loose, warm, sweating, and its far less boring than riding a bike for 5 minutes. I can do all 6 katas in about 12 minutes.