Having a lot of difficulties here. I changed my chain (Shimano IG for a 7-speed Deore DX system) about a month ago and everything seemed fine. There might have been a skip or two but nothing that I thought I would worry about.
I'm currently taking a bike repair course and the instructor said that my rear shifters were really "stiff" so he adjusted something (sorry, can't remember what) and on the ride home the chain was starting to skip. On a ride later on in the week, it seemed to downshift in the rear to the next higher cog/wheel or would try to but it would also seem to skip in place and at times it would upshift too. It seems to just randomly do this whether I am just pedaling along or pushing hard.
So, the instructor had another look at it and suggested to oil/lube the cable guide around the rear derailleur which I did (used Tenacious Oil) and took it out for a spin. What a disaster! It's all over the place.
I had a look at Sheldon Brown's site and one solution was to lube the cable guide. Now, I don't know what else to do...class is tomorrow night by the way.
Any suggestions appreciated. Thanks!