so i'm fairly new to cycling (May 27) I bought a Trek 7500Fx hybrid and I'm having a little troubles with it. Besides the chain constantly wanting to wrap itself around my chain stay, sometimes when I ride at a fairly high rate (18-20mph) on the second chain ring the force of my pedaling will cause the chain to "skip" almost a half rotation every now at then. This wouldn't be such a big deal but it throws my body all out of wack. It is like pedalling and missing. Now I understand that I might need to be on the largest chain ring when reaching these speeds but it doesn't seem to want to run smoothly unless i'm above the 22mph range. It sounds like it is dragging the chain through the derailleur below 22mph. Can anyone suggest anything? I've taken it to my LBS twice and they just adjust the derailleur and send me on my way. I'm starting to dislike them since I took my bike in last time on a thursday and Monday they still hadn't called. I got there and they said "oh well it has been sitting here all weekend because we didn't know what to do with it since the mechanic on duty the day I took it in didn't leave a note explaining what was wrong. Anyways..opinions and advice are much appreciated.