In addition to component quality issues. already thoroughly covered, there is the assembly/adjustment problem with department store bikes. They are put together by contract personnel usuallly who are paid piece rates. Per posts here from someone who did it for a while the rate per bike allows about 10 minutes per bike for all unpacking, assembly and adjustment IIRC. Proper assembly and adjustment cannot be done in that amount of time and an improperly assembled and adjusted bike can be Dangerous!