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.
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
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)
"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.
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.