Originally Posted by
livedarklions
Just keep the 30 ring and remove 4 teeth from it. That's how it works, right?
No, that is not how that works at all. To make a difference in the gear size, you have to actually change the diameter of the chain ring, which will necessitate changing the number of teeth to maintain compatibility with the chain. Since chain links and chain ring teeth are pretty much standardized, most people simply refer to the chain rings by the number of teeth on them, and it is assumed that there are no missing teeth on the chain ring.
There some skip-tooth chain rings out there, as well as some non-standard chains and cogs, but generally speaking, chain ring teeth and chains conform to an expected standard size.