Originally Posted by cyccommute

We could probably quibble on whether or not an 8 speed chain is the same width as a 6 or 7 speed chain. The difference is quite small although the cog spacing is slightly different.

However, a large part of the reason that you haven't broken a chain in over a decade is because of the way that chain are made and why you can't reuse pins on chains anymore. Peening, or mushrooming, the pins of the chain let them take more side force without slipping off like they could in the 5, 6 and 7 speed days. But the peening means that pushing the pin out widens out the hole in the plate and it won't hold if the pin is just pushed back into place.

Cleaning and lubrication does little to keep the chain from breaking and the peening means that the chain can be shifted under load. Add in the shift ramps on cassettes and chainrings and shifting under load is a worry of the distant past. Good riddance too.