OK, I don't have experience with the fighting with other dog problem, but I do with the bicycle, motorcycl thing.
I have a large 130 pound dog so I know how tough it can be when they decides to take out after something. I started to expose him to more traffic, and I also started to say "bicycle" when i saw one coming, so he wouldn't be surprised. Then when the bike went by I would yank him back with the leash and say "NO", the instant he showed any interest. At first it was a battle of strengths, you might even have to wrestle him to the ground and hold him in a dominant manner. But he gets the message, and began reacting less and less. It got to where he would only look in their direction, but I corrected him for this too. Timing is crucial here, you must react the second that he reacts. Now when a bike goes by he just glances with mild curiosity. Or if he hears the word "bicycle" he begins looking around in a calm manner. (if you say "rabbit" or "squirrel", he starts looking around with more intensity, haha)
If we are away form traffic for a while, he sometimes needs a little refresher course, but it usually only takes one or two reminders. Also when walking, be sure that he's not allowed to walk ahead of you, this makes a big differece in how my dog behaves, alphas are always in the lead!
If this doesn't work for your dog, you may have to reinforce your dominance in other ways too.
I agree with Cesar, give exercise, disipline and affection, but only in that order.
Also, sometimes dogs just need a reminder, they see something, get excited, and forget what they have just learned. With my dog I use what I call a pokey stick. A small short stick thats long enough to give your dog a light poke in the ribs or butt. When his instincts take over his training he gets a little poke, not in a painful way, just a surprise, and it snaps his mind right back to you and him instead of what he sees coming down the road.
