Thanks for the warm welcome!
The reason I wanted to use a road bike is because they are so much more efficient. Smaller tires, lighter frame, less power to go faster. Etc.
But, I can now see how a smaller frame would only amplify the amount of vibration caused by the engine, being as they are probably more rigid.
The bike I now have in mind is called a fixie, its a walmart special for 99 bucks. Seems like a cross between a road bike and a hybrid, and have seen online a couple people who have motorized with great success, and not much complaining. One guy , my size (5'8", 150 lbs or so) said he was able to hit 38 on flat ground with stock everything, right from the factory.pretty impressive on a walmart special, and also pretty freaking ballsy!
I have cruised this site for a long time, but never really searched too hard. has anyone tried using any vibration dampeners. Maybe pieces of rubber where the engine mounts to calm down the vibrations?