This is just the beginnings of this article, which will discuss how various aspect of bicycle geometry affect the ride of the bike. I will gradually be adding to it from time to time.
Other bike articlesThe longer the wheelbase of your bike, the less you will feel bumps. Your weight is mainly on your bottom. Since your bottom is closer to the rear wheel, it is mainly the rear wheel bumps that you feel. Think of it this way. If the front wheel goes over a 1cm bump, then a point halfway between the front and rear wheels will rise then fall by 1/2 cm, and a point just over the rear wheel will feel little movement (since the bike will be rotated slightly about the rear wheel, a location just above the rear wheel will feel a slight movement backwards, then forwards. In general, the longer the wheelbase, the longer the chainstays, and your bum will be more towards the center of the bike rather than over the rear wheel, thus making the bumbs seem less extreme.
Similarly, if your hands are right above the contact patch of the tire on the ground, you will feel front wheel bumps the most. If you can get your hands behind (or even in front of) the contact patch, the effect will be lessened. However given any particular frame, getting the right riding position is far more important than where your hands end up at with respect to the tire, so this isn't a very useful bit of information.