Originally Posted by
cyccommute
“Missing teeth” on chainwheels usually aren’t missing. That’s a design feature, although a fairly early one. The flattened teeth are meant to aid in shifting by releasing the chain easier on shifts.
Thank you this is the same crankset
https://www.ebay.com/itm/284517359013 and it has the "missing teeth" indeed. I do wonder why someone changed the crankset from biopace to this.