Originally Posted by
dddd
The teeth on the smallest cog can be functionally repaired in most cases by adding a short bevel to the "hooked" corner of each tooth.
The bevel should be slightly more in line with the driven face of each tooth than with the top edge of each tooth. 30 degrees or so from the driven face is ideal.
Pictured here is a slightly-worn cog. Note the small bevel on the tooth marked "ba", that's all that is needed to prevent the problem of "failure to engage" that causes the skipping, and that occurs when a tensed chain meets the sharp, hooked corner of the sprocket teeth when you apply pedaling force.
dddd - thanks for the idea. So you're saying that if I just took a grinder and nipped the corner off of each of the teeth on the small cog, it might solve the problem? If I understand your instructions correctly, it would look something like the following (the red line represents where I'd make the cut):
