Originally Posted by
Sy Reene
Obviously this system works and not disputing.. but why is it that in my head I'm imagining that after running the chain thru the RD, it would take up more than the extra 1" that was added at the end of this process?
If you look at the rear derailleur you will see it is stretched into a straight line when the chain is completely tight so it adds nothing to the required chain length. The extra 1" gives enough chain length for the chain to climb over the chainring and cog teeth during a shift. This is critical if you shift into big-big.