Can-Am Spyder Rear Mud Flap

If you’ve ridden your RT or ST Spyder in the rain, or after a hard rain, when the roadway is still wet (and perhaps muddy) then you know that the rear fender of the Spyder does not prevent the spray of water (and mud) from covering anything on the rear seat, or with an empty rear seat, onto the back of the rider, even to a muddy spray onto the back of the helmet of the rider. This happened to me returning from my last tour, almost getting into my garage before the skies opened up with a downpour.

I searched the Internet attempting to find a mud flap / splash guard for the rear tire of my ST Spyder but could not find one that was designed for the Spyder (wide) rear tire so I decided to (attempt to) fabricate a custom splash guard for my new bike.

The first challenge was to determine the size of a splash guard that would block the tire spray of the rear tire. I assumed that the spray was coming from in front of the rear fender, being ‘sucked’ up onto the rear of the bike above the seat.

Using a manila folder as pattern material I drew a rectangle, 12” wide by 8” tall, and then rounded the corners where the guard would be attached to the front of the rear fender, and then rounded, with a slant, the front corners that would extend under the rear seat of the bike. (See pictures below for mud flap shape.)


The second challenge was to find a suitable material from which to fabricate the splash guard. After visiting several automobile parts stores I chose the Highland brand, a large sized, generic fitting stiff plastic material from which I could cut a splash guard for my bike based on the pattern I had created. Pictures of the package of the selected generic mud flaps are included below:



The pattern (not to scale) included below shows the rounding of the corners where the splash guard will be attached to the top of the rear fender of the bike, and the ‘slanted’ rounding where the splash guard extends under the rear seat of the bike. The outside dimensions of the splash guard are 12” wide by 6” tall. The holes are 10” on center, ¾” from the rear edge of the splash guard. Carefully drill the holes avoiding letting the drill bit slip or wander from the measured center points of the holes. A pre-drilled, small starter hole is a good idea!

The rear fender has round indents where the bolts attach the fender to the rear fender frame. Rubber washers and galvanized washers that will fit snugly into these round indents will provide a spacing that will protect the fender from being scratched by the newly attached splash guard, and allow the original bolt holding the fender to the bike frame to be tightened properly.

The picture below show the newly fabricated splash guard attached to the rear fender of the bike. Note that the front of the splash guard will touch the underside of the rear seat area, an interior fender, when the bike runs over a curb, speed bump or other obstacle on the road. At this writing, with the fender just installed, no conclusions have been reached as to any difficulties caused by this ‘touching’.


After finishing the fabrication and installation of the new splash guard on the front of the rear fender it occurred to me that I could use the same pattern, with relocated attaching holes, to create a splash guard for the rear / bottom of the rear fender of the bike. This splash guard would be attached using the bolts of the license plate, positioning the splash guard on the inside of the fender rather than the outside of the fender as was the case in the front mounted splash guard.

A second splash guard was cut from the second mud flap. The license plate was removed, with the holes on the top of the license plate providing a template from which to determine the horizontal positioning of the holes for attaching the rear splash guard. A horizontal line drawn 2 ¼” from the top of the splash guard provided the vertical positioning of the holes. Carefully position the license plate, centering the plate onto the splash guard, with the horizontal line centered in the license plate holes to provide the centering points for the two holes to be drilled for attaching this rear, lower splash guard.

The picture below shows the lower rear splash guard after attaching it to the inside of the rear fender using the license plate bolts. Heating the splash guard using a high heat hair dryer or even higher heat paint scraping heater, bending (vertically) the splash guard just to the outside of the attaching holes on both sides will allow the splash guard to more easily fit into the curve of the inside of the fender behind the license plate.

The two pictures below show the lower splash guard, attached, from the rear, and from the side.



The lower, rear splash guard will provide good protection against both mud and gravel when a trailer is towed behind the bike.

There is a question (in my mind) if the front splash guard is actually necessary, but in the absence of convincing evidence to the contrary, it will remain on the bike, with monitoring to be sure it does not damage the underside of the rear seat, or sustain any damage itself.


About justanoldguy

Retired Computer Programmer. Born and Raised in Missouri. Graduated from Missouri School of Mines in 1964. Retired in 2003. Moved to Colorado in 2010. Enjoying good health and 'front range'. Touring frequently on Can-Am Spyder motorcycle. Skiing during the Winter months at Monarch Mountain Ski Area (for free!).
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