Yuba Kombi Bicycle Mudguard Upgrade

The Yuba Kombi is a great cargo bike, however, you notice that it was designed in California as the skirt guard over the rear wheel is not really sufficient to fully protect from rainy wheather. Here I would like to share how I constructed a mudguard for the rear wheel, and also added an extension to the existing front wheel mudguard.

Notes

My Yuba Kombi (without electric motor) was built in 08/2022 according to the identification plate, so all the measures given here are for this model, should there ever be a design change of the bike by Yuba.

Whenever I am talking about the already existing front wheel mudguard that comes with the bike, I am specifically calling it the "Yuba Kombi front wheel mudguard". Whenever I am talking unspecifically about a mudguard here, I am refering to the new stuff to be added to the bike.

Materials

SKS Bluemels basic mudguard set 24" 60 mm black

Aluminium flat bar 11.5 x 2 mm (or similar size)

Some piece of scrap wood, about 1 cm x 2 cm x 10 cm (or anything similar)

Tools

Tape measure

Masking tape

Pencil

Hack saw or multi cutter tool

Pricker (to mark where holes are to be drilled)

Drill and drill bits, 4 mm, 4.8 mm (if available), 5 mm

Two pliers (to bend the aluminium flat bar)

Cutting pliers

File

Rivet gun and blind rivets, 4.8 mm x 6 mm, 4 mm x 10 mm, 4 mm x 6 mm

Not having a rivet gun is not a deal breaker, as the necessary connections can also be made with corresponding screws and nuts. Yet having a rivet gun makes your life way easier, and deep down you always wanted to have one, so this might be the perfect excuse to finally get one ;)

For the rear wheel, a proper protection in rainy muddy weather is missing on both ends - at the back the dirt gets thrown up against the child seat(s) installed on the rack, and on the front the frame gets caked in mud.

On the front wheel the existing mudguard could be longer, as also here stuff gets thrown against the frame.

Unfortunately, not too many off-the-shelf mudguards are available that fit 24" wheels and that are also wide enough. I saw someone else on the web recommend the SKS Bluemels basic mudguard set 24" 60 mm (picture shown here is from the manufacturer) for the Yuba Kombi, so I gave it a try. However, for my taste the rear wheel mudguard was not long enough to give full protection. So I decided to cut the front wheel mudguard in half, and to use one part to make the mudguard for the rear wheel longer, and the other part to extend the already existing Yuba Kombi front wheel mudguard.

I used two of the already existing screws in the Yuba Kombi frame to mount the rear mudguard, the one in the diagonal frame part going to the rear axel, and the one hidden behind the rear light (both can be seen in the pictures). To connect the mudguard to those screws I prepared fitting angle brackets from the aluminium flat bar.

The front wheel mudguard comes delivered with an angle bracket that needs to go. Use an appropriate drill bit to drill through the rivets, remove those, and then discard of the angle bracket.

On the front wheel mudguard, use the tape measure, the masking tape, and the pencil to draw a line at 20 cm from the end with the SKS logo. Use a saw or a multicutter tool to cut the front wheel mudguard in two. This will leave you with a shorter 20 cm piece and a longer 40 cm piece. The shorter piece will be used later to extend the Yuba Kombi front wheel mudguard (see at the end), we will continue now with the longer piece.

On the longer piece of the front wheel mudguard, draw a line at 16 cm from the end that was not cut. Take the rear wheel mudguard and align the pointed end with this line. Draw the outline of the pointed end onto the masking tape. Apply more masking tape to the sides and draw a line about half a cm from the edges. Along this line, cut away the edges until you meet the beginning of the pointed end outline.

Align the longer piece of the front wheel mudguard on the inside of the rear wheel mudguard, and mark where to drill two 4.8 mm (or 5 mm) holes through both to hold the rivets. Those two holes do not need to be at exact positions, I used 3 cm and 11 cm from the cut end of the longer piece of the front wheel mudguard. Use 4.8 mm x 6 mm rivets to firmly join the two pieces. This correspondingly results in a 16 cm elongation of the rear wheel mudguard, thus yielding an overall length of 116 cm.

Cut a 7 cm piece from the aluminium flat bar and draw a line at 3 cm from one end. On the short arm, drill two 4 mm holes, one at 7 mm and the other at 18 mm from the line. On the long arm, drill a 5 mm hole at 33 mm from the line. Take two pliers and bend the bar at the line, to about 105 degree.

Repeat, but with a 6 cm piece of aluminium flat bar. Again, draw a line at 3 cm from one end. For the short arm do the same as above. For the other arm drill the 5 mm hole at 23 mm from the line. Bend to about 95 degree.

Take the cutting pliers to remove the corners and use the file to blunt the cuts.

The 7 cm angle bracket will be fixed on the rear wheel mudguard directly at the pointed end, where the elongation starts. Position it there, with the short arm of the angle bracket pointing to the middle, and and mark where to drill two 4 mm holes through the rear wheel mudguard. Fix the angle bracket with 4 mm x 10 mm rivets to the rear wheel mudguard.

The 6 cm angled bracket gets positioned at 37 cm from the other end of the rear wheel mudguard (the end with the SKS logo), again with the short arm pointing to the middle. Similarly, drill two 4 mm holes, and then attach with 4 mm x 6 mm rivets.

To mount your new rear wheel mudguard, it is not necessary to remove the rear wheel. You need to remove all the holding straps of the skirt guard, then it is possible to bend, wiggle, and squeeze the rear wheel mudguard in between tire and skirt guard, from front to back. Attach the rear wheel mudguard with the two angle brackets to the frame, using the existing screws. Put the skirt guard back in place and strap it back to the frame.

Initially I planned to include a firm connection between the rear wheel mudguard and the skirt guard, e.g. by making two holes and joining them with a zip tie, but it seems that the skirt guard simply by physical contact is already keeping the rear wheel mudguard in place. Similarly, I also planned to attach the end of the rear wheel mudguard to the end of the frame in order to have another connection point, e.g. by using some stiff wire. However, this also seems to be stable enough without. It wobbles a bit left and right, but nothing dramatic. If I change my mind and add more firm connection points, I will also give this here an update.

The remaining shorter piece of the front wheel mudguard will be used to extend the existing Yuba Kombi front wheel mudguard. This can be done without removing the front wheel. Take the piece of scrap wood to protect the tire, and drill two 4.8 mm (or 5 mm) holes in the Yuba Kombi front wheel mudguard. Those two holes do not need to be at exact positions, I used 2.5 cm and 5 cm from the end. Similarly, drill corresponding holes in the shorter piece of the front wheel mudguard. Use 4.8 mm x 6 mm rivets to firmly join the two pieces. This results in a 12 cm elongation of the Yuba Kombi front wheel mudguard.