Any sort of unexpected shaking from your bike can be a big deal. If your fork shakes, vibrates, or makes noise when you apply the brakes, your bike might have a serious mechanical issue that could lead to components failing while you ride.
A bicycle can shake when braking due to headset, hub, or axle issues, or the wheel is out of true. Brakes can also cause a shaking fork.
Luckily, it’s pretty easy to narrow down the cause of these shakes and figure out where the problem lies. Once you know what’s causing the shakes, you can often fix the issue yourself at home.
For many fixes, all you’ll need is a few minutes and some basic tools you probably already have lying around in your garage.
Here’s a quick rundown of most of the common causes of fork shaking and what you can do to diagnose and repair these issues. If you’ve been encountering other issues with any areas of your bike, be sure to start your troubleshooting there first.
The headset on your bicycle is the assembly of parts that connects your fork to your handlebars and frame. It’s a complicated bit of kit that includes bearings, spacers, stems, and a number of screws that need to be carefully tensioned to keep the parts together while allowing your handlebar to turn.
Headset issues can be complicated to fix at home, but it’s usually pretty easy to figure out where the issues are coming from. All it takes is a bit of patience.
Diagnosing the headset
When diagnosing a headset issue, your sense of touch is extremely important. First, squeeze your front brakes and try to rock your bike back and forth with the front wheel pressed firmly on the ground.
Does anything feel like it bends? If you turn the wheel 90 degrees and repeat the same test, does anything change? Noise, rattling, odd bending, and looseness are all bad signs here.
It can be helpful to engage the lockout on your suspension fork before you do this sort of test, but you can usually tell the difference between play in your headset and play in your suspension.
If you feel any knocking, bending, or other weirdness, try putting your hands over various parts of your headset and fork as you repeat these tests. You should be able to feel the bend as it happens, enabling you to track down the problem.
Regardless of whether or not you uncovered anything, try moving on to more localized tests. Try holding your bike by the head tube and wiggling your fork, holding the bike by the head tube and wiggling your handlebars, and holding your bike by the fork and wiggling your handlebars.
Again, you’re listening for rattling and feeling for odd bending or any unusual looseness. Be sure to wiggle in all directions to cover all of your bases.
Fixing the Headset
If there’s an issue that seems to come from your headset itself, it’s often best to call a mechanic and ask for help. Your headset is a piece of your bike that’s very easy to work on from a tools perspective, but it’s also very easy to mess up.
You’ll definitely want a torque wrench to make sure your screws are tight enough to hold but not so tight that you pull out the threads, and many jobs will ask for bearing grease, spacers, and other things that you might not have handy.
A lack of tools and experience means that the sort of headset adjustment that takes a professional mechanic five minutes can easily take a novice well over an hour.
Some common issues include an improperly tightened pre-load bolt, causing the whole assembly to be loose, poorly fitted bearings, wear on the bearings, or improper spacers, causing tension on the wrong elements or preventing tension on the right elements.
Uneven wiggling from your fork and handlebars generally indicates a bearing issue, while getting similar amounts of play from both usually means that you can adjust the headset in some way to solve the issue.
Try slowly tightening your pre-load bolt. If you don’t see improvement within a half-turn or so, it’s probably a good idea to pop open your headset and take a look inside.
Make sure that the cap is tensioning against the frame and not your steering column, that any spacers in use seem solid, and that there’s nothing visually wrong with the internal components of your headset.
You can solve the first two issues by adding or replacing spacers. Anything that seems to be damaged, missing or uneven inside your headset should be carefully fixed or replaced.
Bearings that are too small or too large can cause inconsistent shaking and wiggling. If this is the case, you’ll want to replace the bearings with a size more appropriate for your bike.
A somewhat more subtle and insidious problem can arise when someone services your headset and puts it back together in the wrong order. Putting a bearing seal on top of a bearing instead of below or vice versa can cause the sort of inconsistent shaking issues you’re trying to troubleshoot.
For this reason, it’s extremely important to consult all available manufacturer documentation and keep a record of the order of parts in your stack while you work. Many seasoned mechanics lay the stack on their workbench in order as they take it apart, making it easy to put back together when they’re done.
Hub and Axle Issues
A wheel that’s not spinning properly can shake and wobble. The amount of wobble from this sort of issue can change as you apply dynamic forces to the wheel and axle.
When you brake, you shift the way your weight is being applied to the wheel, changing the stresses on the axle, meaning a wobble that had previously been under control might come out in full swing.
Your hub is the part of your wheel that contains bearings, enabling it to spin. Your axle is the solid part around which your wheels spin. If these parts aren’t functioning correctly, they can cause your wheel to spin at an angle, spin unevenly, or grind against bearings, causing friction, wobbling, and shaking.
Issues with your hub or axle vary. In some cases, you can make a quick adjustment and get your bike working perfectly, but in others, you’ll need to replace your hub or axle entirely.
A Quick Note On Quick Release Axles
Before we continue, it’s worth noting that the quick release lever on your bike’s wheel isn’t a magical device that keeps everything properly centered and adjusted. Instead, it’s a tool that lets you pop the wheel off faster.
Centering your front wheel can eliminate or prevent a whole slew of problems, so it might be worth taking the time to open your quick-release mechanism, visually center your wheel, and then tighten the quick-release mechanism from both ends.
If you feel like you made a big adjustment, try giving your bike a quick test ride and see what happened to your shakes.
Diagnosing Hub and Axle
Diagnosing hub and axle issues usually involves trying to wiggle the wheel independently of the fork while the axle is firmly attached to the fork. If the wheel wiggles, that’s a bad sign.
Another simple test to consider involves spinning your wheel while the bike is on a stand, upside down, or otherwise held upright. If the wheel isn’t rubbing against anything and seems to grind to a halt or wobble on its own, that suggests a hub or axle issue.
It’s often difficult to determine exactly what component of the hub and axle assembly is causing a problem before you pop the whole thing open and look inside.
Broken or bent axles can seem similar to bearing issues, even to experienced mechanics, and odd issues like bearings sneaking loose and getting into odd places are virtually impossible to diagnose from the outside. This means that you’ll want to do a bit of exploring before you order new parts.
Fixing Hub and Axle
Hub issues can often be solved by opening the hub, cleaning it out, replacing the bearings, and putting in a new set of bearings and grease. If any components are found to be damaged while you’re working on the hub, you can replace those to fix your problem.
Just like with your headset, you can work on your hub and axle with a few simple tools you likely have at home, but you might want to leave it up to a professional.
In addition to tools, you’ll want a degreaser and grease for your bearings. You’ll also probably want to replace your bearings, which means you’ll want to have some new ones handy.
Seasoned bike mechanics tend to consider bike bearings inexpensive and often replace them every time they pop open a hub, but you might not have a giant bucket of properly sized ball bearings handy.
Just like with your headset, the sort of maintenance and adjustment that would take a professional a few minutes could easily take you a few hours or even days, especially if you have to order a part online.
This isn’t to say that you shouldn’t work on your hub at home, but rather that you shouldn’t expect it to go perfectly smoothly if it’s your first time opening up a hub.
Any issue with your axle usually means you should replace your axle. Visible wear indicates stress on the metal, which could fail suddenly while you’re riding, while bends or breaks are strong indicators that your axle is no longer safe to ride on.
Is The Wheel True?
In the cycling world, we use the word ‘true’ to refer to the shape of your wheel’s rim relative to an ideal, perfect circle. A wheel that’s tilted to one side relative to the hub, flat or misshapen along the rim, or otherwise non-circular needs to be “trued,” or adjusted until it’s in a better state for riding.
You can often tell how true a wheel is visually by spinning it. Put the bike in a stand, flip it upside down, or otherwise get your front wheel off of the ground and give it a good spin. Examine the wheel from multiple angles.
Does it appear to be circular and pointed at the right angle? Is it wobbling? Is it rubbing on anything or vibrating? If your wheel can’t be wiggled from side to side while it’s stationary but wobbles while it’s spinning, that’s a good indicator that your wheel isn’t true.
Wheels are trued by adjusting the tension between the spokes and the hub.
Bike wheels are sort of like suspension bridges in that the spokes of your wheel exert tension between the hub and the rim, keeping the hub in the middle. Not only are spokes elastic, but they’re also easy to adjust at home with tools you likely have in your garage.
As with the other issues discussed so far, a professional bike shop will be able to true your wheel a whole lot quicker than you can at home.
Unlike your headset or hub, however, you’re less likely to find out halfway through that there’s a part or tool that you need and have to run out to your local bike store or wait for an online order. That doesn’t mean things will be fast.
Truing a wheel is a slow, time-consuming process that’s much faster with a bike stand, a special gauge, and a special tool called a spoke wrench. You can absolutely make it without these tools, however, and as long as you go slow and follow some basic guidelines everything you do will be totally reversible.
Spoke wrenches are very cheap online, but be sure to measure your spoke nipples and get the right size. Alternately, just use an adjustable wrench to turn your spoke nipples.
Without tools to help you determine how true your wheel is, consider putting down a solid white surface to serve as a background to help make it easier to visually identify the relative position of your rim.
The actual technique involved in truing a wheel is simple. Loosen spokes that you want to make longer, tighten spokes you want to make shorter. Adjust spokes by a quarter turn at a time.
If you’re adjusting a wheel laterally, adjust pairs of spokes on both sides of the wheel at the same time to maintain the same overall tension. In other words, don’t add a bunch of tension to your wheel by only tightening spokes on one side.
Instead, make small adjustments by tightening one spoke, then loosening its partner on the other lateral side of the wheel, keeping the amount of tension in your wheel even.
Spokes get looser when you move the nipple away from the hub and tighter when you move the nipple towards the hub. Use the right-hand screw rule to keep your rotational direction consistent while working on both sides of the wheel.
Take your right hand, make a thumbs-up sign with your thumb pointed in the direction you want the spoke to go, and turn the nipple that way.
Be patient, go slow, adjust a quarter turn at a time, keep things balanced, and you’ll get your wheel trued in no time. Bike wheel spokes tend to need adjustment every once in a while, so truing your wheel will likely improve the ride quality of your bike regardless of whether or not it fixes your shaky fork.
Finally, the brakes themselves are a likely culprit for any issues that you experience only while you’re braking. Moreso than the other parts, brakes are easy to adjust, clean, and replace yourself.
Start with a simple visual inspection of your brakes and see if there are any obvious issues. Look at how the pads meet the rotor or rim, how even the action of each half of the braking mechanism is, and look for signs of dirt and wear.
If your brake pads seem dirty, start by cleaning them. Ideally, you’ll pick up a specialized cleaner for this, but soap and water work fine with most brake pads. You definitely want to avoid strong solvents or degreasers.
Try to avoid touching disc brake rotors as much as you can, as they’re somewhat sharp and your skin oils can interfere with the braking mechanism.
While you’re cleaning your brakes, inspect the level of wear on each pad. If the pads seem worn down, you’ll probably want to replace them. Brake pads are very inexpensive, even for fancy hydraulic disc brakes, and you can usually replace them yourself with basic tools with no issues.
If your brakes are dirty, be sure to carefully inspect your rotors or rims for wear. You may find that grit on your brake pads has been dragged along the contact surface and caused damage from friction. It’s very possible that you’ll need to replace your rims or rotors as a result of this wear.
Whether you replace your brakes or not, adjust them to meet the rim at the same time and at the correct angle.
Bike mechanics suggest that the front of your brakes should meet the contact surface a little bit sooner than the back of your brakes. In other words, your rotor or rim should rotate into the narrow part of a very shallow V.
To achieve this angle, slightly loosen your brake pads, insert something very thin at the back, pull on the brakes, and tighten them. When you release the brakes and remove the thin object, they should be toed in properly.
You’ll also want to adjust your brakes to meet the contact surface at the same time on each side and ensure that there’s no rubbing when they’re fully disengaged. Use the adjustment screws on your brakes as much as you can to make these adjustments so you can use your barrel adjusters while you’re out on the track.
If your cables seem worn, frayed, or stretchy during this process, you’ll want to replace them. Just like pads, brake cables are quite inexpensive and require few specialized tools to replace at home.
These steps should restore your brakes to proper working order while giving you a chance to closely inspect things and observe any unusual issues that might be causing your fork to shake.
While your headset, wheels, hub, and axle can all cause a wobbly fork, if your problem only occurs while you brake there’s a good chance your brakes are involved. With any luck, these final steps will resolve your issue and keep your fork secure while you ride.