My chain is catching on the large front chain-ring sometimes instead of shifting to the small ring. It catches on the bottom teeth as shown.



What are some possibly reasons, cross chaining, dirt, bad teeth on ring, etc??? I noticed it happens while in a bigger cog in the back.
(Question)


Thanks,
Marty

PS, I use this as my chain lube but I'm open to changing it. Amazon.com: Dumonde Tech Lite Bicycle Chain Lubrication