>>1314108Okay, I have some time to explain. There are a number of differences between a wal-mart bike and a "real" bike.
Let's start with the pedals, specifically the crank. A wal-mart bike will have the chain rings attached to the crank arm via a single bolt. Picture is related. These cranks are both heavy and weak. All of the torque of the rider has to go through that single attachment which is a sever weak point and can break under load or if the mileage gets too high. I have broken that bolt myself back when I was riding wal-mart bikes. In addition the arms are often steel and solid making them very heavy and they tend to have some flex, robbing you of your power. Conversely a modern mid to high end crank will be made of light alloys, will be stiffer and will be much stronger. This is going to help you transfer power, be lighter to help you on hills and is going to be far more durable among other advantages. The nicer ones also have lower friction bearing designs.
Next we'll discuss the frame. The frame of a wal-mart bike will be made out of cheap straight gauge tubing. This is heavy and does not flex in the right ways but does flex in bad ways. It may have poor lateral stiffness or not be vertically compliant. That means that in addition to being heavy (which is bad for hills), it will rob you of your power by not transferring energy efficiently and will be less comfortable on longer rides. A mid to high end frame will have fancy tubing butted to be thinner in the middle saving weight and designed to be stiff in all the right ways and flex in others to make them more comfortable. The nicer frame will generate much less fatigue over long rides.
Next wheels:
