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Condensed answer:

A female axle and hub can accept pegs just fine. Many riders have been running the combo for years without any issues.

For maximum strength and durability, it’s recommended to use 14mm axles.

What Is a Bicycle Axle?

Axles are a support element for rotating parts. (e.g., cogs, wheels).

An axle is either spinning with the wheels/cogs or is immobile and the wheels/cogs are spinning around it.

In the case of bicycles, the wheel is rotating around the axle with the help of ball bearings inside the hub’s shell.

There are two main types of bicycle axles – male and female.

What Is a Female Axle?

Female axles are short and have internal threading. The wheel is secured to the axle via bolts screwed into the axle.

What Is a Male Axle

Male axles are long rods with external threading on both sides. The wheel is tightened to the axle via nuts which screw onto the axle’s threads.

How Does a Peg Attach To a BMX Bike?

A BMX peg connects directly to the axle.

In the case of a male hub and axle, the installation is as follows:

1. Unscrew and remove the axle nut. Remove the washer too as the peg itself acts like one. (Alternatively, you could also put the washer on the inside of the peg.)

2. Slide the peg onto the axle.

3. Put the axle nut into a socket wrench with a long extension and carefully screw it on the axle. Do it slowly to avoid cross-threading.

You will need a long socket extension because you will be screwing the axle nut through the peg.

The graph below illustrates the order of the elements:

If you have a female axle and hub, the mechanics are quite similar. The only difference is that instead of a nut screwing onto a threaded rod, there’s a bolt screwing into a threaded pipe.

The steps are as follows:

1. Remove the female axle bolts and the washer.

2. Put the head of the bolt into a socket and then slide the socket and the washer through the peg until the thread of the bolt is sticking out of the peg’s end.

3. Screw the female axle bolts into the axle.

The image below illustrates the order of the elements.

What Are The Advantages Of Female Hubs?

Strength

A female axle is considered stronger than a male one of the same thickness because it doesn’t extend as much.

Therefore, it’s more difficult to break it because the mechanical advantage (leverage) is lower when exerting force on it.

Or in simpler terms – it’s easier to break a longer stick than a short one.

However, male axles are stronger when they’re thicker than the female ones. For example, a 14mm male axle is considered tougher than a 3/8″ female.

In terms of strength, axles are ranked as follows:

1. 14mm female axle

2. 14mm male axle

3. 3/8″ female axle

4. 3/8″ male axle

Note: This ranking is based on the strength of the center axle itself. In practice, the axle bolts of a female hub are very likely to give up first because they’re weaker than a male axle.

Cost efficiency

Another benefit of female hubs is that you rarely have to replace the axle itself. The most likely part to break is the axle bolt which is cheaper and easier to reinstall

Conversely, when a male axle breaks, you have no option but to replace it.

Protected Threading

Female axles do not have exposed threading and neither do the bolts. Thus, you can’t damage the threads of either component during riding or when doing some sort of peg-less grinding.

In different, the threading of male axles is exposed and can be stripped during riding.

Lighter Weight (Potentially)

In general, female axles are lighter than male axles because they require less material. However, sometimes the difference is too small to matter.

The tables below contain the weight of various female and male hubs:

Table 1: Front Hubs (3/8″/10mm Axles)

Conclusion: Even though there are some very light female hubs, the weight discrepancies between the male and female front hubs are slim.

As you can see, the male axles ended up being a few grams lighter on average. That said, I couldn’t find a male axle under 200 grams.

Table 2: Rear Hubs (14mm axles)

Conclusion: Rear female hubs show a slight weight advantage over the male models. The difference is 6.5% percent in favor of female hubs.

A Clean Look

Some riders find female axles more aesthetically pleasing because no part of the axle is sticking out.

Frequently Asked Questions

Why Do People Run a Female Hub at the Front and a Male At The Back?

Many bikes come with a 3/8″ female front axle combined with a 14mm rear male axle.

The reasons for this combo are as follows:

Strength. A quality, solid 14mm male axle is close to unbreakable. And since the rear axle receives most of the “punishment” during grinding, it makes sense to reinforce this area.

Weight savings. 3/8″ axles are weaker than 14mm ones but also lighter. Over the years, the BMX community decided that a 14mm axle is overkill for the front because the area isn’t as stressed. As a result, 3/8″ axles started getting more traction. A 3/8″ female is chosen over a 3/8″ male because it’s stronger.

Are There Other Axles Beside Male and Female?

Yes. There are also she-male axles.

To a large extent, the she-male axle is the same as a regular female axle. The only major difference is that the center part is longer and thus sits into the dropouts. (In the case of true female axles, the axle bolts are the element in the dropout.)

Some she-male axles combine a male axle on one side and a female axle on the other.