What are the key characteristics of a chain that make it well-suited for road bike hill climbing with a compact crankset, and how do different chain materials, such as stainless steel, nickel-plated, and titanium, affect performance in terms of durability, weight, and shifting efficiency. Are there any specific chain designs, such as hollow pins or DLC coatings, that offer advantages in these areas, and how do they compare to more traditional chain designs. Additionally, how do different chain widths, such as 11-speed and 12-speed, impact performance on a compact crankset, and are there any compatibility issues to be aware of when selecting a chain for this type of setup.