First off, I'm not familiar with bike terminology so pardon my descriptions and please, if you answer, use simple wording.
My Trek 820 fell on the right side and bent the "hanging down gear arm" out-of-line with the rest of the drive train. I took it to the bike shop. They said it was a simple fix. I didn't watch what they did but wish I had. I assume they just bent it back.
Has anyone experienced this? I never realized bikes could be so fragile if they get knocked over. Can you tell me what to do next time to fix it? BTW, I am fairly accomplished with tools. I'm just not familiar with the drive train on a bicycle.
Thanks in advance.