I thought the same thing as well. Try to tighten it tight enough to where you can't move it, see if you can seat the bearings and then loosen it up. The end cap on mine does flex some although not without a tire on it. I asked Terry about the flex and his explanation was that because of where they are, ie end caps, they were designed to be flexiable and give some so that your frame wasn't damaged in a collision with something, but that your bumper would absorb it. So either you have a super stiff arm or you have a cracked frame from impacts. Oh well, you'll learn to live with the flex. I have been pleased with it but I think the tire could be lowered a bit and i'd be just as happy.