In order to fit Honjo aluminum fenders it is important to first determine if there is enough space for clearance. These fenders are not as flexible as plastic ones and can't be forced too much. First check that the rear fender will fit between the chainstays where it mounts to the chainstay bridge, and that the front will fit inside the fork blades, clearing the brake calipers. Next, note that the chainstays cannot be too long or too short or the rear fender will be distorted and tire clearance could be compromised. The recommended distance from axle center to inside surface of chainstay bridge should be 365 mm (tolerances: plus 5 mm or minus 3 mm). Ideally the fenders should follow the curve of the wheel. To assure this, the distance from axle center should be the same to both the inside surface of the chainstay bridge and the inside surface of the seat bridge. It is possible to make up small descrepancies by using spacers, although these should not be more than 8 mm thick. It also important that there is 10 mm clearance between the smallest rear cog and the right-side dropout eyelet. The frame eyelets should be the unthreaded type—threaded eyelets can be drilled out to remove the threads.
For the front, make sure there is at least 49 mm vertical drop between the brake mounting bolt and the center of the brake pad, and no less than 45 mm. The more clearance there is, the larger the tire you can fit.
We do not recommend mounting these fenders with alternative materials such as zip ties.
The idea is to have the fender curve reflect the curve of the rim and tire. You want to avoid stretching the fender so that it becomes oblong. While you want each fender to closely follow the curve of the rim and tire, they can stick out at the rear end a little and still look good.
REAR: First, decide how much the fender should drop below the front mounting point on the rear of the chainstay bridge. We recommend about 4–5 cm. Mark the spot in the center. Make an indentation with the punch so that the drill bit will not wander. Drill the 5.5 mm hole and clean up the edges with the rat tail file. Temporarily suspend the fender from the seatstay bridge; use electrical tape or something similarly temporary. Mount the fender to the chainstay bridge. Now mark the point where the fender touches the center of the seatstay mounting hole. Putting a bit of crayon in the hole can help mark the exact center on the fender. Put the wheel in and check that the fender follows the wheel's curve. Adjust the mounting point until this is optimal. Remove the fender, mark with the punch and drill the hole. Remount the fender at both the chainstay and seatstay mounting points. Again, place the wheel in the frame and mount the fender stay to the frame eyelets but don't tighten it completely. Find the position for the rear mounting hole for the stay hardware. Ideally the stay should slope up at a gentle angle from the frame mounts to the rear of the fender. If it's too horizontal, make the hole higher. If the angle is too steep, make the hole lower. The idea is to get an esthetically pleasing look. Mark the hole, remove the wheel and fender from the frame. Punch and drill the hole for the stay mount.
FRONT: The front fender mounts with a single bolt underneath the fork crown. To find the position, several things need to be taken into consideration. The rear end of the fender shouldn't hang too low; based on the smallest size tire you plan to use, it should clear the ground by 120 mm – 140 mm (if you are planning to use a rubber mud flap, take this into consideration). The front, or top of the fender should then project beyond the fork crown about 270 mm – 280 mm. However, if you have a fork-mounted rack that will sit above the fender supporting a handlebar bag, make sure the fender will clear that, and if you also plan on mounting a headlamp in front of the rack, you must also make sure there will be enough room (sometimes it is necessary to use a cut-down rear fender in front if both rack and headlamp are to fit).
Once you have roughly positioned the front fender, mark the hole position—this may vary depending on whether you have a mounting hole underneath the crown or you will use a bracket hanging from the brake bolt, etc. Remove the fender, punch the position and drill the hole. Now take a small square-faced mallet and from the under/inside surface of the fender, hammer up a bit to make a flat hump so the fender will sit under the fork crown at the correct angle to line up with the wheel. If you don't feel confident doing this, you can also adjust the angle by getting a thick rubber washer from the hardware store and cutting away some material so that the top and bottom faces aren't parallel. If this is not done, the fender may not line up with the rim and tire.
Mount the fender under the crown, and as with the rear, loosely mount the stay to the eyelets and find the most esthetically pleasing position for the rear stay mount. Mark the position, remove wheel and fender, drill, and install hardware.
FRONT AND REAR: The stay will most likely be too long. Once you have the fenders on the bike and the stay hardware mounted, mark the correct length for the stays. Use a hacksaw to cut off extra stay material. Smooth the edges with a flat file.
You can use either hex head, button head or socket head screws to mount the fender to the frame mounting points. A trick to eliminate squeaks and rattles is to make a leather washer to go between the fender and the frame.
Don't overtighten the hardware—especially at the eyelets. These are small threads and they break easily.
Before you ride the bike, make sure the eyelet hardware on the rear drive side clears the chain when it is on the small cog.
