Bhopping is a bug in the source engine typically used to create speed and conserve it. Other source based games have entire levels designed to use this bug. Bhopping works in two parts, creating speed and conserving it

The way you conserve speed is by jumping, and not just willy nilly. In order to conserve speed you need to limit the time on the ground, and depending on some game settings you might need to hit frame perfect jumps.

This is where it can get very complicated the simple version is that "In order to bunny hop in Half-Life and its expansions, you must strafe using the A/D keys while turning the mouse in that direction, i.e. if you strafe right, you turn your mouse right. By doing this, you will gain speed upon every successful jump. It’s important not to hold forward, or it will not work." - https://wiki.sourceruns.org/wiki/Bunnyhopping
This article explains the physics way beyond my understanding http://flafla2.github.io/2015/02/14/bunnyhop.html

The only setup that i'd recommend is opening dev console and binding mouse wheel down to jump. You can do that with the command
"bind mwheeldown +jump"

There are a lot of places where bhopping can come in handy, whether you're doing the challenges or just playing through the game. I plan to make a list of levels that can be shortened by a significant margin with bhopping but for now, I made a level that requires bhopping to finish.


Here's the workshop link