A rachet consists of a 
round equipment or a linear rack with tooth, and a pivoting, spring-loaded finger known as a pawl that engages one’s teeth. The teeth will be uniform but asymmetrical, with each tooth having a modest slope on one edge and a very much steeper slope on the different edge.
When one’s teeth are relocating the unrestricted (i.electronic. Ratchets Wheel forward) way, the pawl without difficulty slides up and over the delicately sloped edges of the teeth, with a early spring forcing it (often with an audible ‘click’) into the depression between the teeth as it passes the idea of each tooth. When the teeth move in the opposite (backward) direction, on the other hand, the pawl will capture against the steeply sloped edge of the 1st tooth it encounters, thus locking it against the tooth and preventing any further motion in that direction.
Backlash
Because the ratchet can only stop backward motion at discrete factors (i.electronic., at tooth boundaries), a ratchet does allow a limited amount of backward motion. This backward motion-which is limited to a maximum length add up to the spacing between your teeth-is called backlash. Where backlash should be minimized, a simple, toothless ratchet with a higher friction area such as rubber is sometimes applied. The pawl bears against the top at an angle in order that any backward action may cause the pawl to jam against the top and therefore prevent any more backward motion. Since the backward travel distance is generally a function of the compressibility of the great friction surface, this mechanism can bring about significantly reduced backlash.
This Ever-power 54t Ratchet kit works as a primary replacement and is super easy to install. Just remove the freehub body the parts you find here will be in there, grease up the new parts and re-assemble the hub. Boom! You’ve simply substantially increased the engagement points on your hub. To give you a better idea of how this increases your ride think of the engagements in levels of a circle, with the 18t you need to move the cassette 20 degrees to attain the next engagement and with the 54t that knocks it down to 6.66 degrees! That’s less than a 3rd the length it needs to move to hit the next tooth! You may be wondering when you can really see the difference. Only pedal your bicycle around and keep carefully the bike moving through the use of little pedal strokes and back-pedaling. You will see there’s going to be lot’s of slop between engagements. Picture if that “slop” was decrease to a third! I’m sure imaginable that is clearly a huge upgrade. Therefore, if you weren’t already entirely convinced on the 54t ratchet system I hope this can be the turning indicate getting one!