As the rains return to the northern hemispheres, many cyclists’ thoughts turn toward fenders (or mudguards, as British riders call them). Fortunately, the idea that fenders are just an afterthought is long passé – today, most real-world bikes are designed with fenders in mind from the onset. Just like Porsche and Ferrari only sell cars with fenders…
Whether you are planning a new bike or retrofitting an old one, fitting fenders takes some consideration. Well-mounted fenders enhance the appearance of the bike, and they disappear when riding – until the roads get wet, when they protect your body and your bike’s drivetrain from the road spray that makes life so miserable.
Poorly designed and/or poorly mounted fenders rattle and resonate, they drip water onto your feet, and they often break prematurely. Sometimes, they even catch on the front tire and send you over the handlebars.
The best fenders are stiff enough to hold their shape, long enough to prevent front wheel spray from reaching your feet and drivetrain, and have rolled edges that keep the water inside, so it doesn’t drip onto your feet. The Honjo aluminum fenders Compass sells meet all these requirements, plus they are lightweight and beautiful.
Once you have ridden with these fenders, you realize that plastic fenders are at most “50% fenders” – they keep some water off you, but they offer only 50% the protection and riding comfort that you get with the Honjos.
Requirements for good fender installation:
- Clearance (required). Some riders manage to squeeze a fender into a 5 mm gap between tire and frame, but ideally, you should have about 30 mm between the tire and the bridges/fork crown. 20 mm (above) is workable, but if you have much less then you are running into safety risks. On some bikes, it may be necessary to switch to narrower tires when mounting fenders.
- Chainstay bridge (highly desirable): If your bike doesn’t have a chainstay bridge, fender mounting will be difficult. There are work-arounds, such as using a clamp on the seat tube and cutting the fender short, but they are less than ideal.
- Drilled bridges (required): If your chainstay and seatstay bridges aren’t drilled for fenders, then fender installation will be difficult. Ideal is a vertical drilling (above), which allows direct mounting of the fenders. The Honjo fenders we sell come with a sliding bracket that allows mounting the fenders on a seatstay bridge drilled horizontally for a rear brake.
- If your bridge isn’t drilled, you can drill it yourself and install a rivnut. Rivnuts usually are used to retrofit waterbottle bosses on older frames.
- Equidistant bridges (desirable): When you look at the three photos above, you see that the gap between tire and bridge is the same at the seatstay and chainstay bridges, as well as the fork crown. (The same applies to any fender mounting points on the racks.) This makes it easy to get good fender lines and to install the fenders stress-free, which is crucial for their longevity. If your bridges aren’t spaced correctly, you’ll need to figure out spacers to mount your fenders.
The short summary of the above: As long as you have adequate clearances, you can use Honjo fenders.
Which fenders for which tire size?
Generally, fenders should be about 40% wider than your tires. This allows them to wrap around your tires without encroaching on the required clearances. This works well for tires up to 42 mm wide, which are best used with 58-60 mm-wide fenders.
However, you cannot scale up fenders indefinitely: Fenders wider than 60 mm do not work with “road” drivetrains, as the chain hits the fender in the smallest gears. For tires wider than 42 mm, stick with a 60 mm-wide fender. Choose a model that does not wrap around the tire very far, and mount it higher above the tire to provide the required clearance. You get a bit of “air” showing between tire and fender, but this “motocross” look is inevitable if you want to run ultra-wide tires with a road drivetrain. (Mountain bike cranks sit further outward and have room for wider fenders.)
Here is a list of Compass tires and recommended fenders:
- 700C x 26 mm tires: Honjo smooth 700C, 41 mm wide.
- 700C x 28 mm tires: Honjo smooth 700C, 41 mm wide.
- 700C x 32 mm tires: Honjo 700C, 45 mm wide, smooth or hammered.
- 700C x 35 mm tires: Honjo smooth 700C, 51 mm wide.
- 700C x 38 mm tires: Honjo smooth 700C, 51 mm wide.
- 650B x 38 mm tires: Honjo 650B fluted; Grand Bois 650B hammered.
- 650B x 42 mm tires: Honjo 650B smooth or fluted; Grand Bois 650B hammered.
- 650B x 48 mm tires: no fenders currently offered by Compass.
- 26″ x 1.25″ – 1.75″ tires: no fenders currently offered by Compass.
- 26″ x 2.3″ tires: Honjo 650B smooth. These fenders are 60 mm wide and don’t wrap very far around the tire. The 26″ x 2.3″ tires have the same outer diameter as 650B x 42 mm tires, so 650B fenders are a good choice.
If you buy your fenders from Compass Bicycles, we include a reprint of Peter Weigle’s article on fender installation in Bicycle Quarterly 34, with easy step-by-step guidance on how to indent the fenders for fork crown and chainstays (don’t cut aluminum fenders!) and how to mount them free of stresses, so they will give decades of silent, trouble-free performance.
Click here for more information about Honjo and Grand Bois fenders.