Originally Posted by
noglider
As cog size decreases, the rate of wear increases. If you spend a lot of time on a small cog, it wears out very fast. Also, below 12T or so, the power transfer becomes wavy as the chain engages the teeth one by one. The trend is for smaller and smaller cogs and chainrings. I wish it went the other way, even though that would increase cost and weight.
A bigger concern for pro's than me. Correct but not too consequential for downhill coasting.