From what I know, it's pretty useless to "stretch" before a workout. Essentially, you're stretching when you follow that muscles normal range of motion anyways. The important thing to do before a workout is to get the blood in the muscle pumping. This is what essentially lessens the chance of injury. (Your biking, for example, is great) Another great thing to do before lifting heavy is to lift light. Before you go for the heavy weight, go for the easy weight, and do a few reps so that you get a nice blood pump going, and then overload...
Stretching is best done after exercising, since muscles tend to cap off unless stretched after a workout. Stretching will ensure better flexibility and increased muscle growth.
Oh, and just to clarify as many did above, soreness is normal, and always a good thing when experienced the day after, as long as it doesn't borderline pain...
