"Even Steven"

Slaloming through construction on the roadways, I ended up limping home, out of the saddle, trying to force my weight onto the front wheel so as not to shred my rear wheel. While I don't normally ride on a flat, the rest of the way was smooth, and I just didn't feel like walking the last bit. Besides, I needed to let the dog out.

The cause of the flat turned out to be a large staple, probably courtesy of one of the industrial packages of equipment which accompanied the construction. But, if that's the worst of my troubles, it's a blessing...

Upon pulling the rear wheel to change the tire, I saw a definite pattern on my rear sprocket, shown in the photo at left. It seemed like wear, but was actually a thin layer of road grunge on the darker teeth. As I pondered the sprocket "flower", it struck me that this was perfect example of why you hear not to run "even" gearing. In this case, the drivetrain in question was from my Dawes, running a 42 x 16T. (My Panasonic fixed sports a 42 x 15T)

The "inner" plates of the chain brushed just that much more on every other tooth, while less contact occurred from the "outer" plates. (if the image isn't quite clear, you can click on it to see a larger version.) There you have it, the "two-tone" sprocket! Other cyclists had metioned that you "shouldn't" run even tooth sprockets on front and rear, but here is the actual result of such behavior.

For what it's worth, the sprocket scrubbed up just fine and there didn't seem to be excessive wear on any set of the teeth. Upon replacing the rear wheel with its repaired tire/tube, I set the cog teeth forward one, so that the inner plates were contacting new teeth.