A sudden change in weather can easily disrupt plans. All it takes is for the rain to start falling for you to end up riding on wet asphalt, through puddles, or on damp gravel. Spray from the wheels ends up on your shoes and clothing, mud covers the bike and luggage, and continuing your route becomes much less pleasant. To prevent an unexpected rain shower from ruining a ride, it is best to equip yourself with fenders in advance.
However, there is no universal solution suitable for every route. On wet asphalt, long, full-coverage fenders offer better protection, while on gravel and dirt roads, you must take tire width and the available clearance around the wheels into account.
In this article, the experts at Routes and Roads explain how to choose fenders for riding on asphalt, gravel, and forest trails, how to find the right size, and how to verify their compatibility with your bike.
Summary:
Why use fenders
Types of fenders
Which fenders to choose based on your route
Fender compatibility with your bike
How to choose the size of your fenders
Conclusion
Why use fenders
When a wheel rolls on wet asphalt or a damp path, the tire picks up water and mud particles present on the surface. As the wheel rotates, centrifugal force flings them upward and backward onto the bike, your clothes, the cyclist, and those riding behind you. Even during a short ride, this quickly becomes very uncomfortable. If you are riding for several hours, your clothes and shoes risk ending up wet and covered in grime.
The effectiveness of fenders largely depends on how much of the wheel they cover. A long model intercepts more water, while a mudflap at the end further reduces spray coming off the wheel. Compact models cover a more limited area and only protect certain parts of the bike and the cyclist.
Fenders protect the cyclist from mud and road spray
Types of fenders
The design of a fender determines the surface area protected, the mounting method, and the space required around the tire. For rides outside the city, there are mainly three types: full-coverage fenders (also called fixed fenders), removable fenders, and compact fenders.
Full-coverage fenders
A full-coverage fender follows a large portion of the wheel's circumference and sits relatively close to the tire. Its large surface area captures the majority of water and small debris. The lower the front and rear fenders extend, the less water reaches the cyclist and is sprayed backward.
These models are generally attached at several points on the frame and fork. Additional stays stiffen the assembly and limit movement on uneven surfaces. This is particularly important on degraded asphalt and gravel: a poorly attached fender can vibrate and rub against the tire.
Full-coverage fenders are not compatible with all bikes. Their installation requires sufficient space between the tire, the frame, and the fork, as well as suitable mounting points. You must also maintain clearance between the tire and the fender so that the wheel can turn freely and mud or small stones do not accumulate.
The large surface area of a full-coverage fender protects against most road spray
Removable fenders
If the frame does not have mounting points for permanent installation or if you only need protection occasionally, removable fenders are a practical solution. Depending on the model, they attach to the seatpost, frame, or fork. Their effectiveness depends on their length, the portion of the wheel covered, and their position relative to the tire. The shorter the fender, the less it protects against spray.
Compact fenders
Mini mudguards are placed under the saddle, on the fork, or near the wheel. They are lightweight, take up little space, and are suitable for bikes where it is difficult to install full fenders.
This type of fender acts in a more localized way. A front model, for example, reduces the amount of mud flung toward your face and certain bike components, but it protects legs from water less effectively than a long front fender.
Which fenders to choose based on your route
The type of bike gives a first indication, but the nature of the road surface and the weather on your route are even more important. The same gravel bike might be ridden on wet asphalt, compact gravel paths, or muddy forest trails: the fender requirements will not be the same.
Fenders for wet asphalt
On wet asphalt, tires continuously spray water from the road surface. In these conditions, full-coverage fenders that cover a large part of the wheel are generally the most effective.
Mudflaps placed at their lower ends provide additional protection. A long front mudflap reduces water spray onto your shoes and the lower part of the bike, while at the rear, it limits spray toward the cyclist riding behind you. This configuration is very well-suited for long road rides and group rides in wet weather.
On wet asphalt, wheels kick up a cloud of spray
Fenders for gravel
On gravel, you must find a balance between protection and the space available around the tire. The fender must be wide enough to protect against water and small splashes of mud, while leaving sufficient clearance between it and the tire.
Gravel bikes are generally equipped with wider tires than road bikes. Before installing full-coverage fenders, check the available space at the fork and rear triangle. On compact gravel paths, this solution effectively protects against water if the bike allows for installation.
The more a route involves wet dirt and sticky mud, the more important clearance becomes. Mud increases the actual volume of the tire and fills the space under the fender, while small rocks or branches that get stuck can hinder wheel rotation.
For routes in the Île-de-France region or the Chevreuse valley, it is better not to rely solely on the term "gravel," but also on the condition of the trails, the season, and the weather.
Gravel quickly throws small particles of mud onto the frame
Fenders for dirt roads and forest trails
On muddy forest paths, covering as much of the wheel as possible is no longer necessarily the priority. Dirt can accumulate on the tire, while branches, stones, and other debris may get stuck between the wheel and the fender.
For these routes, it is important to maintain significant clearance around the tire. On mountain bikes and bikes regularly used on wet terrain, removable fenders and compact mudguards are particularly practical. They leave more space around the wheel while protecting the most exposed areas without tightly hugging the tire.
For forest riding, it is important to provide sufficient clearance for mud
Fender compatibility with your bike
Having the right diameter and width is not enough to guarantee a proper fit. The design of the frame and fork determines the available space and mounting possibilities.
Start by locating the intended mounting points near the frame dropouts, on the frame bridges, and at the fork crown. Full-coverage fenders are generally attached at several locations. If the necessary eyelets are missing, choose models for which the manufacturer provides an alternative mounting solution.
Then, evaluate the available space above and on the sides of the tire. Do not check only with a clean tire: during a ride outside the city, mud, small stones, and branches can accumulate under the fender. Some front full-coverage fenders are equipped with stays featuring a safety release system. If an object gets caught between the tire and the fender, the attachment can detach to reduce the risk of the front wheel locking up.
If your bike is equipped with a rack, check the position of its stays and mounting points. Some systems use the same eyelets on the frame. Also consider bikepacking bags: the fender, tire, and luggage must not come into contact during movement and vibrations on uneven surfaces.
The fender must be compatible with the bike's geometry
Disc brakes do not in themselves prevent the installation of full-coverage fenders, but the position of the caliper can influence the position of the stays. Always check the mounting method in the manufacturer's instructions for the chosen model.
How to choose the size of your fenders
To choose the right size, take three parameters into account: the wheel diameter, the actual tire width, and the fender width.
Start by checking the wheel diameter. The designations 700C and 29″ correspond to the same rim diameter of 622 mm at the bead seat, while 650B and 27.5″ correspond to 584 mm. However, the same rim diameter does not necessarily mean that the same fenders are suitable for both wheels.
The next parameter is the width of the installed tire. The fender must be wider than the tire to intercept water sprayed onto the sides of the tread. Manufacturers generally indicate a range of compatible tire widths: use these values to choose a specific model.
For example, a 700×28C road tire and a 700×45C gravel tire mount on wheels with the same rim diameter, but their width and volume are very different. It is therefore not possible to choose your fenders based solely on 700C, 650B, 27.5″, or 29″ designations.
Wide tires require a fender of appropriate width
Conclusion
For rides outside the city, choose your fenders based on the surface, weather, and your type of bike. On wet asphalt, a large protective surface area is particularly important. When the terrain becomes more demanding, clearance around the tire and the reliability of the mounting become more important.
Before purchasing, check your tire dimensions, the available space, and mounting points. At Routes and Roads, you will find fenders for road bikes, gravel bikes, and touring bikes. Our experts can help you choose a suitable model and verify its compatibility with your tires, frame, and already installed equipment.
