The key advantage is simple—

an 18T pulley dramatically reduces the chain’s deflection angle.

Compared to an 11T stock pulley, the chain runs straighter with less bending.

And why does deflection matter?

The more it bends, the more resistance you get.

More resistance means lower efficiency.

So the value of a large pulley isn’t just the size—

it’s about giving the chain a smoother, more efficient path to travel.