Figure 25 comprises two drawings demonstrating how you can use a ruler to experience the effect of stiffness when loads are applied to a beam. Lay a ruler flat on the desk in front of you. Place your hands, palms down, on each end of the ruler such that you cannot feel the ends of the ruler in your palms i.e. the ruler sticks out a little way from each hand. Now slide the ruler back towards you until you reach the edge of the table. Continue to slide the ruler off of the table whilst placing your thumbs underneath the ruler in order to hold the ruler against the palms of your hands. Pick up the ruler and raise it in front of you. Keep it horizontal. Rotate your fingers so that they grasp the ruler. Now try to bend the ruler. It should be quite easy. Now rotate your hands up so that the ruler is vertical on its edge. Place your thumbs under the edge of the ruler and now try to bend it. It should be a lot harder and you should be able to feel the ruler attempting to buckle.

 2.4 Bicycle structures