I used to work at a shop that WOULD NOT for any reason work on Walmart/Target type bikes. They weren't being snobs. It's because the quality control on the manufacturing and components on those bikes is so bad AND they are assembled by folks that generally don't know much about bikes, that it's tough to get them dialed-in...if you can at all.

To the nay-sayers: Go to walmart, target, or toys r us and check out the bikes. The brakes work on only half of them.

Tune ups on high-end bikes are a snap and get harder as the quality of the components goes down.