I took my Trek bike in to fix the chain missing cogs and squeeky brakes. They finished in about 10 minutes and charged $35. I rode away, realizing the bike didn't shift any better and brakes still squeeked, but assumed they knew what they were doing and I wasn't riding the bike correctly. It only got worse, so I recently took it to another bike repair person, who explained / showed how the chain has stretched and the cables needed replacing, as they also stretched. If I didn't get a chain that would meet the sprocket teeth correctly spaced, the sprocket would be ruined. I was also told, the squeek was due to the angle of the rubber pads. They needed to be angled forward for correct quiet use. A repair shop should know about chains and brakes. If they don't know, they have no business charging $35 for their ignorance.