Mark Bulgier wrote:
>
>Re: block chain - there's no real advantage, other than correctness for a
>certain restoration, right? Isn't it just heavier, with more friction and
>wear when compared to roller?
I have a 1916 Mead Ranger with the original chainring and (probably) chain. I also have a repro of the catalogue. Mead was a multinational manufacturer, and the catalogue makes a big deal about the (American) bike having the newfangled, superior, English-made 1/2" chain, but mine has 1". My theory is that they planned to use the English chain, but the demands of the war on British industry made this unavailable for export.
Actually, there is a superiority to 1" chain, it can be much longer wearing than 1/2" chain! Here's the deal:
The usual mechanism of chain/sprocket wear is that the chain pivots wear, causing a slight elongation of the distance between the rollers. The "stretched" chain no longer matches the pitch of the sprocket, so the sprocket teeth wear to accommodate the worn chain. If you then install a new chain on the worn sprockets, the mismatch will cause the chain to wear rapidly until it matches the worn sprocket teeth.
Here's the kicker: the chain elongation only happens on the half-links connected by outer plates; the center-to-center distance of the rollers connected by inner plates is still exactly 1/2". Thus, once the chain begins to wear, every other sprocket tooth is running on an off-pitch roller, while the alternate teeth are dealing with chain that's essentially "new." For this reason, I'm always careful in servicing tandem synch chains that have even-sized chainrings (as most do) to maintain the phase relationship betwen the teeth and the inner/outer chain links.
It is not practical to maintain this phase relationship on a multi-speed drive train, and it is impossible if one of the sprockets has an odd number of teeth.
With 1" chain, however, there's on tooth per _complete_ link, so as the chain and sprocket wear, they constantly match one another perfectly. I believe this considerably reduces system wear, and I've never seen a worn out 1" chain, though most of the ones I've seen have been very old.
Sheldon "Inch Pitch" Brown
Newtonville, Massachusetts
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