Cassettes explained please

[OakLeaf]

There's definitely a difference between my 25 and my 27. I first put on the 27 the year I did Columbus Fall Challenge, and I really think I would've been suffering on that ride without it.

The difference would be somewhat smaller between 28 and 30, but I'd think you'd still notice it on the steepest hills where you'd be using your lowest gear.


I'm not sure you'd really want to swap out the single cog. Whatever your jump is now (whether 24 to 28 or 25 to 28), adding two teeth to it would make it an ENORMOUS jump, which not only would be hard on your legs, but your RD as well. I can't imagine smooth shifting over a difference of 5 or 6 teeth, especially downshifting when you're really going to be wanting to preserve momentum. Since you'll have the cassette off anyway, you'll have to have bought both cassettes, and you'll have to adjust the B-screw, what is the advantage to swapping only the cog vs. the whole cassette?