How to Fix Mountain Bike Mudguards That Wiggle

A mountain bike mudguard is a component that can be attached above the wheel of the bicycle to prevent mud and water from splashing on the cyclist, nearby riders, and their bikes. They are often made of plastic or metal and can be quite fragile. If they are not attached properly, they can easily become damaged and start to wiggle. In this article, we will show you how to fix mountain bike mudguards that wiggle.

To fix mountain bike mudguards that wiggle, reinforce the mudguard bridge bracket with a stronger L-bracket, add a strip of metal ribbon along the length of the mudguard, replace the V-stays, add a second strut, and tighten the mudguards.

Why do Mountain Bike Mudguards Wiggle?

Mountain bikers can benefit from installing mudguards on their bikes because deflecting mud and water will ensure they maintain a better grip on the bike and a clear vision of the path ahead. Ensuring that the mudguards are installed properly on the bike frame can prevent the mudguards from shaking loose on bumpy terrain. 

Mountain bike mudguards wiggle when the attachment system is loose, when the points at which the stays are attached to the brackets rip out, when the mudguard stays are of low width gauge, and when the mudguard is too flexible and lacks reinforcing metal or rigid plastic strip.

Our article about how to install mudguards on a mountain bike has step-by-step instructions on correct placement and attachment methods.

To fix mountain bike mudguards that wiggle, secure the mudguards to stay like this
Mudguards are necessary components to install if you want to optimize your safety and cleanliness. Image Source: Bikerumor.

Here are the most common reasons for your mountain bike mudguards wiggling:

1. Loose Bolts, Nuts, and Screws at the Attachment Points Make Mudguards Wiggle

Loose bolts, nuts, and screws at the attachment points can damage mudguards. This will cause them to wiggle and eventually fall off. To prevent this from happening, make sure that all bolts, nuts, and screws are tightly secured using the necessary wrenches on a multitool like this. Our article about how to install mudguards on a mountain bike explains how to choose the correct mudguard type and style for your bike as well as various methods to attach them to the bike frame. 

When installing your mudguards, make sure to use the correct size bolts, nuts, and screws. Mudguards that are attached with tools that are too small are more likely to cause wiggling. Consult the instruction manual to make sure you are using the correct tools and materials.

2. Weak and Long Mudguard Stays 

If the mudguard stays are not durable and of low gauge width, they will not be able to support the weight of the mudguard, causing it to wiggle. Therefore it is important to use quality mudguard stays with high gauge width. Our guide on key mountain bike fender parts and their functions, explains the various brackets, screws, and clamps like this that can be used to attach mudguards to a mountain bike.    

Make sure that the mudguard stays are properly attached to the brackets. If they are not attached correctly, they can easily be damaged or even fall off entirely. To keep this from happening, it is important to follow every step of the instruction manual, like this one from TOPEAK, correctly when installing your mudguard.

If your mountain bike has stays that are not robust, your mudguard will become loose and start to wiggle when riding on rough terrain.
Weak and thin stays can be the cause of a wiggling mudguard. Image Source: Cnd.road.

3. Thin, Long MTB Mudguards Without V-stays or Strut Supports Tend to Wiggle

If the mudguard is too flexible and lacks reinforcing metal or a rigid plastic strip it is more likely to wiggle. If improper support is the cause, using a thicker and more rigid mudguard will fix things.

Alternatively, if you do not want to replace the entire mudguard, you can add a strip of metal ribbon along the length of the mudguard. This will help to stiffen it and prevent it from wiggling.

If the V-stays are weak, it is recommended that you replace them with stronger V-stays like these. This will help to support the weight of the mudguard. Once you have reinforced the mudguard, make sure to tighten it to stop it from wiggling. Our article about mountain bike fender accessories explains how the choice of fender stays and washers can help reduce wiggling and rattling on your bike’s mudguards. 

4. Front Mudguards Extending More to the Front From the Fork Sometimes Wiggle

If the front mudguard extends excessively to the front from the fork, it can easily become damaged and start to wiggle. Attachment bolts that are not properly secured are often the cause. It is important to double-check whether all of the attachments are securely fastened to avoid the front mudguard from extending too much. Our step-by-step instructions to adjust mountain bike fender offset explain how to adjust the fender's position so that it doesn’t extend too far.

If your mountain bike fender extends too far it will have less support and will wiggle around loosely.
The further out a mudguard extends the more it bounces and flexes which could cause wiggling. Image Source: Amazon.

How to Fix Mountain Bike Mudguards That Wiggle

Mudguards not only protect the rider from water and mud but also shield the bike components from excess debris that could cause rust, and wear and tear over time. 

To fix mountain bike mudguards that wiggle, tighten loose nuts or bolts at the mounting points, add a second pair of struts if the ones used are faulty, replace weak U or V-stays with stronger ones, and reinforce the mudguard brackets if they are not rigidly in place.

As this article from ESU sustainability consultants explains, installing bicycle fenders reduces the amount of mud that gets encrusted on the bike chain and other moving parts, which helps to prolong the useful lifespan of the bike. 

Try these options to fix mountain bike mudguards that wiggle:

Option 1. Check for Loose Nuts, Bolts, or Screws and Tighten Them

If you notice that your mudguard is wiggling, the first thing you should do is check for any loose nuts, bolts, or screws. If any are loose, tighten them as much as you can without doing damage and stripping the thread. This should secure the mudguard and stop it from wiggling.

Simply use a monkey wrench like this to tighten the bolt in a clockwise direction. We recommend having at least a basic mountain bike toolkit as our mountain bike tool kit essentials guide outlines, to be able to perform these and other minor repair tasks on your own.

Option 2. Replace Weak Mudguard Stays With Stronger Stays

If the mudguard stays are thin or made of weak material, it is recommended that you replace them with stronger V-stays. This will help to support the weight of the mudguard and prevent it from wiggling. Once you have reinforced the mudguard, make sure to tighten it.

To replace weak mudguard stays, first unscrew the old stays. Remove them and clean the space where the new strays will be attached. Attach the new strays with bolts and tighten them. Alternatively, you can use a V-stay like this one instead of a U-stay. V-stays are often stronger and therefore less likely to allow wiggling.

V-stays like these will hold your mountain bike mudguard in place without it wiggling.
Chrome V-stays are stronger and more rigid so they can help reduce fender wiggling. image Source: Amazon.

Option 3. Reinforce the MTB Mudguard With a Rigid Metal Strip Longitudinally

If you want to reinforce a mudguard, you can do so by bolting a metal strip like this underneath it. This will make it more rigid and less likely to move around.

To tighten a metal strip underneath the mudguard first, find a metal strip that is long enough to fit the entire length of the mudguard. Drill holes in both ends of the metal strip. Then bolt the metal strip to the mudguard using washers and nuts. Make sure that the bolts are tight so that the metal strip does not move around. You may also want to use some type of sealant or adhesive to keep it in place.

Option 4. Reinforce the Mounting Bracket With a Stronger L-Bracket 

If the brackets that hold the mudguard to the frame are not rigid, it is a good idea to reinforce them with an L-bracket like this. This will help to support the weight of the mudguard and stop it from wiggling.

To add an L-bracket to the mounting bracket first, find a strong L-bracket and drill a hole at each end of the L-bracket. Bolt the L bracket to the mounting bracket using washers and nuts. Make sure that the bolts are tight so that the L bracket does not move around.

Option 5. Use a Mudguard That is More Rigid

If you find that your mudguard is too flexible, you may want to consider using a different type of mudguard. There are many different types of mudguards available, see our article on how to choose rear mountain bike mudguards for tips on how to identify the best quality models, and how to ensure you buy mudguards that are more rigid and less flexible like this.

Install mudguards that have pivot points but that don’t wiggle, on your mountain bike.
A rigid mudguard with pivot points will help reduce wiggling. Image Source: Amazon.

Examples of Mountain Bike Mudguard Stays to Fix Wiggling Mudguards

A wiggling mudguard isn’t such a big problem to solve and it certainly doesn’t mean that you have to replace your mudguard.

When fixing wiggling full-length or long mountain bike mudguards, tighten all the loose connections, replace or add a second mudguard stay, and change from V-stays to U-stays.

Here is a summary of stays that can be used to reinforce your mudguard:

Type of Mudguard Stays Material Type Example From Amazon Price
V-stays Metal Sks Replacement U Stay Kit ~$15.00
U-stays Steel Sks U-Stay Kit for Velo ~$15.00

How to Fix Your Rattling Mudguard Brackets

The brackets that hold your mudguard in place could definitely be the reason for mountain bike mudguards that wiggle and rattle, in which case you can easily remedy the problem.

To fix a rattling mudguard bracket, first, tighten the connection points, reinforce the bracket with zip ties or Velcro straps, put a leather or rubber washer between the mudguard bracket and the connection point, and if the bracket rivets are loose replace them with pop rivets.

Here are the steps to fix your rattling mudguard brackets:

Step 1. Tighten the Connection Points

The first thing you should do is tighten the connection points. This will help to stop the bracket from rattling and make it more secure. Consider checking your mudguard bracket bolts before each ride for optimal safety and as part of your regular bike maintenance routine. This will ensure you identify possible issues before they cause components to wear out and break. Our article about common mountain bike problems and how to fix them is a good starting point for various issues that you may encounter with your bike, and how to easily prevent or repair them yourself. 

Tighten the connecting points to the appropriate torque to make sure that the mudguard on your mountain bike doesn’t rattle or wiggle.
Tightening connection parts. Image Source: CondorCycles.

Step 2. Use Zip Ties or Velcro Straps to Reinforce the Connection

If the bracket is still rattling, you can try to reinforce it with zip ties like these or Velcro straps like these. This will help hold it in place and stop it from moving around. Again, this might not solve the problem and you may have to change some parts like the rivets.

A convenient way to secure your rattling or wiggling mudguard to your mountain bike is to use zip ties.
Zip ties are great to tighten mudguards. Image Source: MBaction.

Step 3. Place a Rubber Washer Between the Connection Parts

If the mudguard bracket is still rattling after tightening and reinforcing it, you can try to put a leather or rubber washer like this between the mudguard bracket and the connection point. This helps reduce the rattling noise and makes it more secure. As this article from BI&T explains, washers help reduce rattling by spreading the compression load over a larger area and help to keep bolts in place so that they don’t wiggle around when the various moving components are in motion. 

Step 4. Replace the Bracket Rivets

If your bracket is still rattling, you might need to replace the rivets. If the brackets are still rattling after taking the above steps it is usually because you have a lot of mud on your bike, or because the rivets are loose. You can try to remove the old rivets and replace them with new ones.

It is also a good idea to give your bike a thorough clean between rides to prevent mud build-up from causing rust. Our steps to clean mountain bike gears and clean a mountain bike chain properly and lube it explain how important these often overlooked routines can help keep your bike in good working condition and prevent expensive repairs later on.  

Step 5. Enjoy Riding Without Rattling 

After following the steps above, you should be able to ride without your mudguard rattling. If you still experience problems, then have a look at our article about mountain bike fender width to help determine if the rattling could be caused by the mudguard rubbing on the tire or other parts of the bike. 

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