Originally Posted by
cyccommute
Those
are the lift pins. Maybe not as elegant as those found on more expensive chainrings but they serve the same purpose. If they were “yawning cracks”, why are there 3 identical ones in the picture? They are also positioned where you would find pins in the more expensive chainrings
Here’s two other chainrings with similar structures but of a higher quality. A bit more refined but they are there for the same purpose…to lift the chain and aid in shifting. Removing them by grinding them off would be a huge mistake.
did you notice the LACK of gap on the big ring's cheap stamped shift aid "pin" ? (top picture, top red circle).
so, i dug around thru my collection of old MTB cranksets, and found one similar to Kmeyer's... it has the same thing showing, minus some wear... it is an old Alivio crankset, the adjacent teeth are the same height to the right, not worn lower, as pictured by Kmeyer.
Shimano Alivios of that age have Replaceable steel rings, but in a ridiculously tiny BCD size, and
all three rings are held in place at that 67mm(?)BCD. (Sheldon's math says it's 67.66mm, so may be 68mm too... )
Sheldon's cribsheet doesn't list that BCD...
https://sheldonbrown.com/cribsheet-bcd.html
if an old crankset has replaceable rings, and measures about 39.8mm between adjacent bolts..... when it is decided you need to replace rings, replace the entire crankset, and enjoy modern shifting.