XC Mountain Bike Quick Release vs. Thru Axles 15mm front / 12mm rear

For XC / Cross Country mountain bike racing, what is better, quick release or thru axle?


First let explain the 2 different technologies for any riders who aren’t sure what the actual difference is.

A quick release is a solid metal rod usually 9mm that lives inside the an XC mountain bike wheel’s hub, and of course can be easily removed when the wheel needs to be removed from the frame.

A thru axle is a hollow tube, currently 15mm in the front for more expensive Cross Country mountain bicycles and 12mm in the rear of an XC mountain bike rear wheel’s hub.

The advantages of a thru axle:

  • Hollow tubes are simply stronger and have less flex. This why your frame is hollow tubing and not solid, or it would bend and crumble.

The disadvantages of a thru axle:

  • A slight weight gain, as an XC bikes front fork and the frame need to be stronger / reinforced to handle the heavier loads. This can often increase the overall Cross Country mountain bikes weight by as much as 100-300 grams.

The advantages of a quick release:

  • Quick Release technology means a lighter Cross Country Race Mountain Bike
  • QR mountain bike parts tend to be cheaper than thru axle counterparts.

The disadvantages of a quick release:

  • Under heavy loads, very aggressive conditions an XC mountain bike rider will tend to experience more XC mountain bike wheel and frame flexing.

Should you upgrade your trusty XC mountain bike to get a thru axle set up?

Well, before you make this decision, you should first consider if you are in tune with your mountain bicycle enough, or even ride hard enough to notice that this flex even exists. Plenty of riders don’t even notice the difference because they simply don’t push their equipment to the limits.

There is an exception, and if you are the Clydesdale type, even if you don’t ride at the limit you might experience flex often if you have a purchased a lightweight Cross Country mountain bicycle.

If you are Cross Country mountain bike racing competitively, and you have a quick release in the rear, you might consider first upgrading your XC mountain bike front fork, and either swap the front bicycle hub or replace the bike’s front wheel altogether to gain stiffness in the front end of your XC mountain bike.

Often times this enough to satisfy a Cross Country mountain bike racer / rider, since XC mountain bikes typically don’t jump more than one foot to three feet, without damaging their lightweight frames.

Since upgrading to a thru axle is an expensive proposition, the flex is getting to you the time to upgrade might be now. If your next frame is going to be built from the ground up, then you would be able to transfer your front XC mountain bike wheel / 12mm hub and 12mm front fork to the next bike, so this might be a good stepping stone to get the ball rolling.

I have recently read forum posts where other riders discouraged mountain bicyclists for upgrading simply to get a thru axle in the front and rear of their mountain bike. In my opinion if your bike is driving you crazy with the flex when you are powering through rough terrain, this could be a smart move.

However, if you really don’t notice it, perhaps it isn’t necessary to upgrade simply for a thru axle.

Now, if the thru axle is only one of the reasons you want to upgrade, perhaps you want to upgrade to a carbon frame (read our article on Carbon vs. Aluminum) or you also want the newer wheel size (read our article on 26″ vs. 27.5″ vs. 29″ Wheels) then your timing is right for a new upgrade.

In my vast years of riding, I have seen many frames broken, wheels destroyed, including front forks broken at the lower end where they support the quick release and chain stays in the rear. So from a pure safety standpoint, the thru axle gets my vote for its ability to create a safer environment for both XC mountain bike riders and racers.

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