I have developed a strange rhythmic click when I pedal up hills. Not sure what is causing it. I find these little mechanical problems to be irritating, and also a great chance to learn about how to fix a bike. I started my bike repair skills backwards. Learned how to build a wheel before I could do much of anything else. My goal then is to get to the point where I can handle the more basic things like putting air in my tires in the next several years.