In my experience, it's only know as "block chain" if it has solid links between teeth. Otherwise it's a "roller chain," as are all half-inch pitch chains.
Pete Rutledge
Woodbridge, VA
> Greetings, this answer is probably way too esoteric, but I've just had my
> first coffee so here goes. That type of chain, also known as block chain
> goes back to the 18th century, possibly earlier, some early trucks and
> automobiles used a chain as part of the connection from the transmission
> to the rear wheels. It's only natural that it was used on bicycles, how
> else you gona do it. As manufacturing and the want to have more gears
> evolved the half inch pitch evolved, easier to go up and down a freewheel.
>
> Oscar Juner always said that half inch pitch chain did not belong on the
> track, not strong enough, although I did break one in a sprint.
>
> Take care
>
> Jim McCoin
> Fremont Ca.