In days gone by, motorcycle riders needed to be half-competent mechanics to reliably get where they were going. That's changed a lot in the last few decades, to the point where a lot of riders get by without ever laying a spanner on their own machines. But there are still chains.
Chains still need the occasional clean and lube, and as they wear and stretch, you still need to adjust the rear axle back to take up some slack. If you ignore these basic bits of maintenance, you end up having a chain that flops around, jumps off the teeth on the rear sprocket and becomes a safety issue – not to mention making your bike noisy, clattery and sloppy in the gearbox.
BMW now says it's solved these problems with the introduction of a "maintenance-free chain" that doesn't need any lube, and never needs to be re-tensioned.
The BMW M Endurance chain, as it's known, uses an industrial diamond coating on the chain rollers for "extreme hardness and resistance." It doesn't wear off, BMW says, and it "drastically" reduces the friction coefficient where the roller interfaces with the sprocket teeth, and with the bushing surrounding the pin that holds the chain links together, which also gets the "tetrahedrally amorphous carbon (ta-C)," or industrial diamond coating.