SimWorks fields our fair share of inquiries regarding Honjo fender compatibility. In many cases, due to a wide array of factors, it can be difficult to make a confident call without seeing your bike and the fenders you’re hoping to install. Depending on the bike, there are assessments that range from “should be a breeze”, or “if the fender gods are smiling down on you (which is really just a matter of the experience and patience of you or your mechanic)” to “sorry, there’s no way you’re squeezing those in that frame or around those tires”. In addition, there’s the aesthetic consideration. Each of us have an expectation for what we’re hoping our install ends up looking like. After all, we’ll not just be riding these bikes, but photographing them staged ever so elegantly and sharing those photos so as to have our tastes and sensibilities affirmed or scrutinized by honest-to-god friends, internet trolls, and all manner of people carving out space somewhere in that chasm of space between those two extremes.

This entry is intended to be a guide for making some sense of the fitting problems you face if you are thinking of installing a set of beautiful Honjo mudguards on your bike.

Make sure there is enough clearance to fit your fenders

Clearance is the most important factor when determining whether a fender can be attached to your bike.
Without sufficient clearance, you’ll encounter a whole host of potential conflicts- some of which can be problematic to the lifecycle of your equipment or downright dangerous to you as a rider.

First, you need to know your ideal value for sufficient clearance. Simworks recommends 10mm to 15mm depending on the type of bike. More clearance is likely appropriate on touring bikes that are equipped with wide and/or knobby tires and are intended for off-road cycling. Find the best value for your ride and bike style. Error to the side of caution.
Snug fender lines are certainly attractive for setups with tighter clearances, but actual riding can be unnecessarily stressful. These installations are often prone to rubbing. Also, even on dry, paved roads, the sand and pebbles that are often kicked up make a rattling noise. You can reduce these factors by ensuring adequate clearance.

First, figure out the value of your bike’s tire radius. Measure the diameter and halve it, or measure from the hub axle to the outer circumference of the tire. Even if the tire notation shows the same width, various factors such as the presence or absence of knobs, tread thickness, rim width, air pressure, etc. are all factors effecting this value, and the radius changes accordingly. If you can actually measure it, add your ideal clearance value to that value. If the value of the arch radius of the fender is close to that, it means that it should be compatible. There are differences depending on the shape, but an error of a few millimeters can be corrected at the time of installation.

If the fender arches are in good condition, then check the following three clearances- Under the fork crown, under the seat stay bridge, and behind the chain stay bridge. This issue is clear if you can confirm that the fender fits in these points on your frame/fork and that there is enough space for your rotating tires.

Even if there is a gap and it is not enough clearance, you can reduce the tire size (width) to make room and allow it to be installed. For example, lowering 32c to 28c gives a rider an added clearance of 4mm.

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Eyelets and hardware

On the bicycle’s frame, eyelets etc. are required at the place where the stay will be fixed. In addition to under the fork crown, under the seat stay bridge, and behind the chain stay bridge, there are a total of five standard fixing points including the three previously mentioned points, as well as the trailing end of both the front and rear fender where you will be attaching a U-Stay.

The SimWorks by Honjo fender set includes a “Standard Stay Kit”. If your frame is a Sportif or traditional road-esque type designed for fenders, this standard hardware should suffice. However, for frames with large tire capacity, such as modern cross bikes and gravel bikes, the bridge may be too offset from the fender. In such cases, longer-length fender brackets (Dove stay 35mm and Dove stay 50mm) will be required separately. In this way, since the Honjo fender set is a general-purpose product intended to get most users the sufficient hardware they will need. More focused or esoteric fitting components are available, affording installation success in instances where it may have otherwise seemed too challenging or not worth the extra effort.

In addition, the method of attaching to the fork crown or bridge varies depending on the model. The photo above is an example of a common type of installation where the rear dove stay is omitted for a direct mount to the underside of the seat stay bridge. In this particular installation a leather washer is used as a spacer, to prevent chattering, and to help cut down on fender fatigue; all considerations during a thoughtful installation process.

Once you’ve got enough clearance, it’s time to determine what the right hardware is.
The breakdown of the metal fittings that come as standard is as follows.

• U stay
• Stay band set for 4mm stay or 5mm stay
• R clips set for 4mm stay or 5mm stay
• Dove stay for front
• Dove stay for rear

Simworks offers many solutions in addition to those already mentioned, so please use your good sense and aesthetics when choosing hardware. Also, we are always happy to assist in providing recommendations based on our own experience and expertise, or to potentially direct you to a shop or other resource that can help to make this whole process seem a little less daunting.

Drilling Required

The fender body does not have the holes required for mounting. There should be only the necessary holes in the optimum position for its installation. Drilling itself is not difficult, but if you don’t have the tools or you don’t have your own work space, it’s a good idea to ask a shop that specializes in customizing your bike to install Honjo fenders.

You may wish to dent or manipulate a part of the fender, or cut out a part to fit it. These sometimes necessary processes are painstaking but not impossible, but potentially better left to an experienced mechanic with the appropriate tools. The integrity of the fender body is compromised in these instances, so additional care needs to be taken to ensure that the fenders fit and are installed properly.

Please refer to the following articles for additional mounting references and tips
>>> SimWorks Fender fatigue/failure Advisory
>>> Honjo installation tips and insights
>>> Honjo fender stay alignment for maximum structural integrity