Bought a new 12-27 and a subsequent crash
 

Today I went out and replaced my 11-23 (which I love...on the flats) with a new 12-27. After I bought it the LBS install it. After they were done, I knew I should have taken it for a test ride, but didn't.

Later that day, I hit my first signifigant hill. I start climbing up and drop into my 39x27. About 15 spins into that gear my front crank just locks up. I can't move it forward or back. This threw off my balance and down I went. It wasn't too bad as I was going slow and was able to unclip in time to partially break the fall.

I check the bike and notice the chain is stuck between the frame and crank and wont move. I then was able to get it to fall to the crank shaft but I noticed a huge gash on the frame. Its not cracked, but it doesn't look good either.

I finally get it fixed and it happens again. I went to another LBS to have them fix it. Now, was this the fault of the LBS that installed it? What would cause the front chain to pop off like that?

Chain suck!

Don't you need to put on a longer chain to go from 11-23 to 12-27?

sounds like a poorly tuned front derailer.

FD could need tuning. I threw my chain twice yesterday going to my big chain ring climbing Mount Pisgah. I need to adjust it. What can I say. If you had just a new cassette put in and they did not touch your FD, then they are not to blame.

This is a FD adjustment issue, not a cassette. It's possible your FD is loose enough that something jarred it.

Yeah that sucks and has happened to me before (especially when I first started riding). Basically when you get jammed at low speed your screwed because you are clipped in.