Even if you take great care of your bike, unforeseen issues can arise – and a cracked head tube is a concern that demands immediate attention.
The head tube is the part of the bike’s frame that houses the front fork’s steerer tube, and it plays a pivotal role in a bike’s structural integrity and handling.
First things first – if your bike’s head tube is cracked, it is not safe to ride.
A cracked head tube is an issue I’ve come across several times in my years of experience as a bike mechanic, across road bikes, MTBs, gravel bikes, BMXs, and everything else in between.
The most common cause is simply material fatigue from the vibrations of riding and exposure to the elements, but impacts from a crash or even a poorly installed or adjusted headset (the bearings connecting the steerer tube to the head tube) can also cause cracks.
In this article, we’ll be covering the causes of head tube cracks, why the frame material is relevant, the potential dangers of riding a bike with a cracked head tube, and possible fixes that can be made to a cracked head tube (as well as questioning whether that’s really a good idea at all!).
What Is The Head Tube?
The head tube is the furthest forward tube in the bike’s frame and houses the steerer tube, which connects the front fork to the stem and handlebars.
The head tube also houses the headset, which is the set of bearings that act as the interface between the bike’s frame and the steerer tube. This is what allows the handlebars and fork to turn while remaining securely attached to the frame.
Typically, the headset features one set of bearings at the top of the head tube, and another at the bottom.
Head tubes can vary in width and length according to the bike’s size, purpose, and design features.
4 Most Common Causes of a Cracked Head Tube
There can be any number of reasons why your head tube could crack, but these are the four most common I have encountered in my experience as a bike mechanic.
#1. Material Fatigue
Over time, materials fatigue. This is when they are taken to a point where they pass tolerance time after time and eventually become weak and start to crack.
This happens simply from the constant vibrations of riding, and can be exacerbated by exposure to the elements, especially if the bike is stored outdoors in a climate with large temperature swings between summer and winter.
Head tube cracks resulting from material fatigue most commonly begin as a hairline crack on the bottom side of the welded junction between the head tube and down tube, then grow upwards.
However, material fatigue cracks can also appear on the head tube itself.
#2. Impacts
Crashes and other impacts are also a common cause of cracked head tubes. This is partly why it’s so important to check your bike thoroughly after a crash, or take it to be checked by a mechanic if you don’t feel confident assessing it for yourself.
#3. Poor Manufacturing
The next reason you are going to end up with a cracked head tube is due to poor manufacturing, especially if cheap materials are used.
If the bike isn’t well built and the welds or joins are not strong enough, then there’s an increased likelihood that the head tube will crack.
This is especially true if the head tube has been built too tight, in which case the installation of the upper bearing race of the headset or the headset cup can create a small crack which then grows as the bike is used.
#4. Poor Headset Installation or Adjustment
In rare cases, an improperly installed or adjusted headset can also cause the head tube to crack.
Often (as described above) this is due to a flaw in the frame manufacturing, but a severely overtightened headset could also cause a crack, especially if the headset, steerer tube, and head tube are not correctly aligned.
Why Frame Material Matters for Cracked Head Tubes
Aluminum and carbon fiber frames are both much more likely to develop cracks in the head tube than steel frames.
Carbon Fiber
Although carbon fiber is incredibly strong, it only has maximum strength at stress points. An impact at a non-stress point in the head tube can cause a crack.
It’s also worth mentioning that carbon fiber frames can age and weaken quickly, especially those made of cheaper, lower-quality carbon fiber.
Particularly on older carbon frames, the resin that bonds the carbon together has a shelf life and weakens after years of use, making the frame more brittle and susceptible to cracks.
Aluminum
Aluminum bike frames are light, strong, and cheap, making it a very popular frame material. However, aluminium frames are also much less resistant to material fatigue than other metals such as steel. This is why they tend to come with shorter warranties than other frame materials.
Low-quality aluminum alloys used for cheap bike frames are the most susceptible type of frame material for head tube cracks in my experience.
On the aluminum head tubes that I have seen cracked, the cracks most often appear at the welds.
Steel
Steel, on the other hand, is amazing at absorbing impacts and vibrations due to its ability to flex.
This means cracked head tubes are far less commonplace on steel bike frames. The main reason you might see a steel frame crack is if it has corroded or gone rusty in that area.
How Do I Identify A Cracked Head Tube?
Surprisingly, it can be easy to miss a cracked head tube. Not many people notice unless it’s too late and it breaks completely. Here’s how you can spot a cracked head tube:
#1. Visual Inspection
The first way to identify a cracked head tube is by looking.
Typically, you will look for a crack from the top or the bottom of the head tube, stretching vertically up or down. This could be hard to see as many are as small as a hair’s width. It could also look like paint damage, so if in doubt, check with a professional bike shop.
#2. Strange Noises
Another very common occurrence when you have a cracked head tube is strange noises. You might hear clicks when you’re going over bumps, or a cracking or creaking noise when turning.
#3. Vibrations Or A Wobbly Feeling
If you’re riding your bike and feel the head tube gives you a wobbly feeling or it vibrates a lot, then there’s a chance that your head tube could be cracked. The slightly larger diameter of a cracked head tube compared to an intact one is what causes this.
#4. Lumpy Steering
Finally, we have lumpy steering. You might find some resistance or get a lumpy feeling when steering left or right. This is because the bearing track is either cracked or not circular. It’s another potential sign of a damaged or cracked head tube.
Is It Safe To Ride A Bike With A Cracked Head Tube?
In short, no. Cracked head tubes can be very dangerous, and you should not ride a bike with a cracked head tube.
The worst-case scenario for a cracked head tube is that it fails catastrophically, breaking open completely. This would likely see the front wheel or handlebars (or both) become separated from the frame, resulting in a serious crash.
However, even if the head tube doesn’t fail completely, you risk losing steering control and accuracy as the crack causes the tube to deform, affecting the headset bearings and your ability to steer. This in itself could easily cause a crash.
Once a crack appears, it is likely to become worse rapidly, so you should stop riding the bike as soon as you notice it.
Can You Repair A Cracked Head Tube?
When it comes to repairing a cracked head tube, it is technically possible (though not necessarily advisable – more on that later).
There are three main routes you can go down if attempting to repair a cracked head tube:
#1. Replace The Entire Head Tube
Your first option is to find a very skilled welder or carbon fiber specialist, get them to completely remove the head tube of the bike, and replace it with a new perfectly sized head tube back in the correct position.
This will give you the perfect repair, but it will come at a high cost (probably more than the cost of an entirely new frame).
It’s not a route I have seen many riders go down, and this is because of the cost and the time involved, and the required skill and precision of the repairs. You can’t guarantee the head tube angle is perfect afterward, which could permanently affect the bike’s handling.
I would only suggest going down this route if a bike has significant sentimental value or is a rare vintage model. Otherwise, you’re likely better off simply replacing the entire frame.
#2. Weld Repair
The next option is to repair the crack by welding it up. This is mainly an option for steel frames; welding on aluminum frames is technically possible, but much more complicated due to the need for heat treatment of the metal afterward (which creates its own issues).
For steel, it’s a cheap repair, but it will likely leave a mark and look unsightly. It’s also very difficult for a welder to add to the structure of the head tube. You would struggle to guarantee that it will fix the issue, and they have to weaken it further to apply the weld.
#3. Reinforcing Band
The final option that I have seen a few cyclists use on steel and aluminum frames is to use a reinforcing band.
This process involves pressing a tightly fitting metal ring around the head tube to reinforce it. This can help slow the growth of the crack, especially when paired with drilling a small hole at the end of the crack (or just beyond it).
Not only does this solution look awful, it isn’t an especially effective solution. It’s not always going to work properly, and there’s still the risk the head tube can crack further elsewhere or continue to weaken and break anyway.
I’ve even seen some on the internet suggest simply using a hose clamp to secure the area around the crack. That’s not a good idea.
There’s no way a hose clamp will be strong enough to safely secure a head tube crack, given the massive amounts of stress that area of a bike frame is exposed to.
Should You Repair A Cracked Head Tube?
As an expert bike mechanic, I don’t recommend you use any of these fixes above. When a head tube cracks, the structure of the whole frame has already been compromised, and it’s not safe.
You are much better off financially and for safety to completely replace the frameset. It’s easy to want to repair what you have, but it’s always going to worry you, and you’ll never get the same experience since it has cracked.
Should you repair a cracked head tube? You can, but it’s not a good idea.
A Final Note on Cracked Head Tubes
A cracked head tube is a very serious problem on a frame, regardless of whether it’s on a road bike, mountain bike, commuter, or anything in between.
Although you can repair it, any professional with safety as their main concern will tell you to replace the frame completely.
Thanks for taking the time to read our article, and ensure you check out the BikeTips YouTube Channel for all our bike maintenance guides!
