Originally Posted by legalize
This is a picture. The chain is on the smallest chainring. The wear is noticable (already!!!! after 1 hour of use) on the middle ring.
Should those areas that are worn on the middle chain ring be that way ALREADY?
Do you see the "little bugger" on the middle chain ring? This is what the chain gets hung up on
Even when I move the derailer so it does not rub on the chain (by hand) and pedal, the middle chain ring's "little bugger" STILL will pick up the chain (if you are pedaling in reverse, or forwards).
If pedaling forward, and you dont apply torque, things are arent bad and you dont notice
when you apply torque, the chain will hang up much more to the point where it skips and I look down thinking I'm going to see a snapped chain (thankfully I that did not happen)
Do you think my local bike shop put on a bad-fitting middle ring!?
Wow. That's a lot of wear, there's clearly an alignment problem here. Those "little buggers" are intended to assist the shifting process, and in your case, they are causing shifts that you don't want. It's hard to tell if it's because this chainring is too thick or is sitting too far inboard for your setup, or if there's some adjustment that can be made to make it work.
The bottom line is this. Your drivetrain, as they gave it to you, does not work, and they need to make it right. That premature middle chainring wear probably has nothing to do with the derailleur adjustment, it's an alignment issue or a wrong type of chainring. You didn't need a chainring with shifting pins (those "buggers"), but with or without them, this middle chainring just does not work in your setup. Did they even test this bike before they gave it back to you? I don't think so.
They also replaced your small chainring, is that right? I see that it's an SG-X, and the middle ring is an LX? That may have something to do with why they are not working well together, and no, there should not be that visible wear on that middle chainring like that. Something is very wrong here, and they should fix that at no charge to you. Measure your chain, and if it's in decent shape, the rest is their responsibility for the mess they made. It worked well before, now it doesn't work at all.