LZ's Tech FAQ: Technical FAQ: Di2’s fail-safe for short chain stays; more on hoop stress - Lennard answers a reader's question about his Shimano Di2 shifting and explains why hoop stress can damage rims. Read the full article at Technical FAQ: Di2’s fail-safe for short chain stays; more on hoop stress on VeloNews.com. http://ow.ly/5T5X50hjmpk