Answer:
Runs smoother than any rhyme, loves to fall but cannot climb.
The sharp slim blade, that cuts the wind. What is it?
Who is he that runs without a leg. And his house on his back?
Gets rid of bad ones, short and tall. Tightens when used, one size fits all.
Three little letters. A paradox to some. The worse that it is, the better it becomes.
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?