One chain is slightly used and I bought it for a fair price via Marktplaats.nl. Unfortunately, this chain is a bit too short for the gear combination I'm planning (and the parts I have), but I got a few spare links from a nice chap in U.K.
The second chain is brand new and in the original box. I obtained it straight from Shimano's bike museum in Sakai, Japan.
The chain is the heart of the unique Dura Ace 10 mm pitch track series. Regular bike chains have a 1/2 inch (12.7 mm) pitch: the distance from pin to pin. The 10 mm pitch chain has a 10 mm pitch, of course.
The pictures below show the difference between a 10 mm pitch chain (top) and a regular 1/2" pitch chain (bottom).
Due to this special 10 mm pitch chain, all parts involved, as well as the tools, are different.
The distance from tooth to tooth of the chain rings and sprockets is also reduced from 12.7 to 10 mm and als the overall diameters have decreased. This requires crank arms with a smaller BCD (bolt circle diameter) and a rear hub with a smaller thread size.
