Well. You'll never believe this. So the manager checked it out again and he had another manager check it out. They say nothing is wrong with it. Then I tried a spare tire from where I thought it was happening and I didn't notice a difference. We came to the conclusion it was in my head. I never in a million years thought that could be the case. But I guess it is. When I don't focus on it, the bike feels fine. But when I focus on the bumpiness, I notice it. The manager said, ''Don't worry. We've all been there.''