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Mountain bike axles,thru axles, boost and unboost explained

Axles are of different sizes, lengths, shapes, and diameters same as that of the hub of the rear and front tire before there were nut bolt axles that were tightened on both sides with the lock nuts, and that were simple axles of bikes but nowadays there are thousands of brands of axles which differ in their functioning and contains their own nut bolts in shape of skewers that are tightened and loosed for installing of the new axle, installing of wheel and hub.

Tests and experience say that the QR skewers are not good and better for the mountain bikes because of their lower quality, flexible material and these are thin rods as compared to the thru-axles. The mountain biking world is vast, every rider wishes and has installed most firm and rigid axles for both wheels within the hub and these are the thru-axles.

Axles are of different shapes and different methods of their installation:

  • there are QR skewer axles
  • There are thru-axles that have levers on both sides
  • there are axles that are tightened by nut lock bolts on both sides

The sizes of these axles totally depend on the hub sizes and also there are different diameters and lengths of axles for the rear and front wheels and there is also a difference in the axles with different brands of mountain bikes.

Axle has levers on both sides through which you can easily remove the wheel in seconds, that’s why it is a must lock your bike with an unbreakable chain by passing it through both wheels of your bike.

Thru-axle or QR Skewer for front and rear wheel of MTB?

Mountain bike trails are rough and bumpy, QR skewers are thin and flexible rods and even these would feel different in riding a mountain bike on the trails, whole bike balance does not remain the same, and the wheels also become flexible and starts bubbling and the other major disadvantage of skewers is that when the wheel rotates you can hear a sound of rubbing and scratching the axle with the rotors of brakes due to their flexible nature but on the other hand thru-axle gives a smooth way of riding because these are firm and rigid and does not distract the wheel from the way.

The best method would be that you can install the QR skewers in your front wheel and thru-axle in the back wheel because the whole body weight aligns on the rear wheel hub and axle that’s why it would be the safer method to install the thru-axle in the rear wheel.

Quick-release skewer:

These are thin flexible rods fixed within the hub, these contain a lever on their right side and a threaded cap on the other drive side, these also contain an inch of two springs rounded on the left and right sides, these springs are fixed within both threaded sides of the hub and when the bike runs these springs move left and right and prevents the skewer from rubbing with the fork leg.

the QR Skewer is thin as compared to the thru-axle and these are mostly used for road bikes and for front wheels of mountain bikes, these skewers are not used for performing stunts and jumps on the trails because there are chances of breaking and bending of these quick-release skewers.

these are the modern discovery and do not need any spanner and torque wrench to open and change the skewer, it is easy with your hands even in emergency cases, when you are too far from your home and city simply just move the lever of the skewer and uninstall it, if any bending occurred it can easily be recovered by rotational movement of the lever.

Keep in mind to give the specific position to the lever of the skewer so that it will be straight perpendicular to that of the fork directed toward the sky because it saves the lever from pointing things(bushes, trees) on the trail.

Thru Axles:

Thru-axles are different in their shapes from the quick-release skewers. these are thicker and wider and increase in length as compared to the QR Skewers, these do not contain any spring for their installation, these are thick long rods with the lever at one end and the other drive threaded end. these are easily tightened and loosened by rotating their levers in the clockwise and anticlockwise directions.

These are strong and rigid and do not bend easily and are specially used for mountain bike wheels. these are not flexible and do not move around when the wheel rotates, thru-axle easily absorbs bumps from the front tire and carries your whole weight for years. these are long-lasting as compared to the Quick release skewers. they do not break after performing jumps and stunts on the trails, sometimes they will bend if you got a hard crash or accident at a fast speed then simply you can give them again their straight original position by uninstalling applying force on the mid of the thru-axle with a hammer, they do not cause any negative effect because these are made of steel and alloy metals.

Boost thru Axle:

Boost axles are wider and thicker as compared to the QR skewers, these are the classic thru-axle to install on the rear wheel of your mountain bike. these are usually installed in those hubs which are wider and have more space for installing the boost thru-axle.

these are firm and strong with more durability and do not bent and break on the trails, you need a wider hub for installing a boost thru-axle in your bike wheel, also they give a better ride if these are installed in the front wheel hub. you can easily run wider tires and wider wheels on your mountain bike if you have installed boost axles and all these things become possible for your bike. boost thru-axles are for downhill trails and enduro trails.

Non-Boost thru-axle:

Non-boost axles are 10mm narrower than the boost axles and these are the standard axles, you need a narrower hub and wheel for non-boost axles. you need a non-boost frame, non-boost wheels, non-boost rims, and a non-boost hub for installation of the non-boost thru-axle. because the boost thru-axle is wider and does not fit in the cassette, chain, and the legs of the non-boost frame.

Before non-boost axles and wheels were used which were narrower and does not absorb bumps properly on hard trails of mountain bikes and then boost thru-axles were introduced which is a comfortable way for installing wider tires.

The difference in thru-axles for front and rear wheels:

Thru-axles have different lengths and sizes according to the fork, frame, and hub of the wheel. thru-axles are also different in their threads on the drive side, some axles have much more threaded area and the other has smaller pitch threaded area also the width of thru-axles is different for both front and rear wheels.

If you are going to change to your old thru-axle with a new one, then you can order the same size of thru-axle as it ks before within the hub for receiving a new one from an online store, but if you want to buy from nearby mechanic shops then you carry and show your old wheel thru-axle to the mechanic, its a better way of changing old thru-axle with a new one.

The proper way of installing thru axle:

If the thru-axle is not well installed it will cause any danger to your wheel and you on the trails, because if it is loosely installed, it will slowly slip out from the hub and wheel and the other main risk is that it starts creating noise of rubbing which is the reason that mostly the thru-axle become bent because of unconsciousness. the lock nut falls from the threaded drive end and the axle comes out of the hub.

Before going on a ride always check the thru-axle of both the front and rear wheels and tight them for a safe ride.

How to grease the thru-axle of a mountain bike:

Always wet the threaded side of the thru-axle where the cap and lock nut would fit and hold the thru-axle horizontally within the hub. it is necessary to grease the drive side of the thru-axle because it reduces seizeness and increases the durability of the thru-axle plus the wheels of your bike rotate properly without rubbing and unpleasant voice.

Give two to three wraps of grease on the whole side of the thru-axle body, it keeps the axle wet, and its working capacity increases for years.

Can I convert the quick release skewer to thru-axle?

Yes, you can easily convert QR Skewer into thru-axle without using any tool and without going to any mechanic shop to spend any bucks, all this process can be done easily from your hands, you can easily uninstall the skewer from within the hub by removing the lock nut and rotating the lever and insert the thru-axle within the wheel hub.

Rotate the lever of the thru-axle and when it is tightened fully then leave the lever in the straight direction pointed towards the sky, this is an easy method of changing any bike thru-axle by the DIY method.



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