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How I made my wood fenders

Wood fenders have been used for bikes since there were bikes. While they don't have the durability of plastic or metal, they look nice and can be quite light.  With a little maintenence, they can last many years. I got into making fenders for my little wheel bike more out of neccessity than choice. There was no rear fender I could buy for my 16" 306  wheel. Fronts are avaliable because of their use on recumbents, but the only rears I could find were wide bulky water gutters taken off an old folder or kids bike.   Kent Peterson wrote up a page on how he make fenders out of coroplast, a cardboard like material made out of plastic. The owner of River City Bicycles in Portland OR makes a variety of attractive wood fenders out of hardwoods. His  shop specializes in fitting them to road bikes with limited clearance under the brake. The fenders are cut in half to avoid the brake area altogether, and custom hardware has them mounted in front of and behind the brake. Paul Sykes (also in Portland)  makes wood fenders and sells them locally. Either of them would custom make me a set, but I figured I would rather give it a shot myself. It wasn't that hard to do. If I ever broke a fender, it would be easy to make another blank. Other than a table saw and a propane torch for the hardware, I used only basic tools are used making them.

Here is the rear one after a sanding. It's made out of 3 layers of redwood, and it weighs almost nothing. It's not flimsy though; actually it feels more stout than a plastic fender. Now I make them out of cedar, since redwood is brittle, and I broke a fender on a curb. The cedar ones are holding up fine, after 2 years of pretty regular use in all kinds of weather. Obviously, the fender is flat. On the positive side, this makes it easier to eject any pebbles or detrius that gets stuck in there as you roll along. If mud accumulates, it is more easily removed, than in a curved fender. In puddles or standing water, if you are going fast enough, spray can exit the side of the fender, where a curved one may prevent this. For the most part though, flat fenders seem to do 95% the job of curved ones in keeping me dry.

I cut thin slabs of wood off a window sill I got out of a dumpster at a house renovation site. The house is on Scott st. in San Francisco, and was built in the late 1800s. It survived the fire and earthquake of 1906, but I guess the window had to go. The clear old growth redwood was in great shape under the exposed exterior. I cut thin slabs of material off with the saw, about 1 mm thick. You can see them laying to the left of whats left of the sill. Thinner than 1 mm was too thin and difficult to cut. A bit thicker was okay, but a 1.5 mm thick piece would not form around the tire-form without cracking.

I needed to glue the 3 thin slabs together over a form. For the glue, I used "gorrilla glue". It is totally waterproof, which is of course rather important....  It is avaliable in most mom 'n' pop hardware shops.    Following the directions, I wetted the surfaces of one side, on each of the layers to be glued. I just ran them under the faucet for a moment; each one.

Next, I put the glue on this middle piece on both sides, and spread it out with my finger (wearing gloves).

These pictures show how I used inner tubes to strap the lamination to the tire. I have since begun to use duct tape for this instead. It's a lot easier to work with.  I had about 15 minutes of open time to glue the layers together. I used an old 16" rim with an inflated tire on it. I put the layers together (the wet sides went against the middle glued layer), and wrapped them over the tire. I then wrapped an old inner tube around the wood and the tire. With another inner tube, I wrapped the initial tube against the tire to keep it from slipping off. Then, I wrapped 2 additional tubes around the fender/tire circumference, so it followed the tire line well, and the glue was held with pressure. Fifteen minutes was enough time to do this, but there is no time for answering the phone or making a cup of coffee during this task.

Here you can see a close up of the lamination. Glue is being squeezed out between the layers. It is all dried and set up in about 3 hours. On an earlier lamination, I wrapped the inner tube around the wood and rim. The resulting fender had warpage where the tube had wrapped around.

Another view of the setup. Have to be careful to avoid having the tube slip off before I can wrap some tube around the rim at either end of the fender.

Now it's all dried, and a hard foam like layer is visible along the edges where the glue foamed and squeezed out. I removed this with a coarse file, the one below on the grinder. Then I sanded it to 120 grit on both sides

After several applications of tung oil, and making the hardware to mount them, it's done. The redwood is very weather resistant, and could simply be left as is and allowed to grey naturally. But the tung oil should increase its life, and it brings out the color. My new cedar fenders have been left natural and look very business-like.

When I released the fender from the inner tubes after the glue had set, it sprung back a little. Just enough to give it a good accurate curve around the tire when it's about a centimeter away from the tire surface. I should have cut the bottom of the fender off and installed a mudflap, because it caught on a steep curb I rolled off of, and it broke near the brake.

The eyelet attaching the front fender support to the bike is open at the front. If a stick falls against the support while riding, it will pull it out. If it does not pull out from the fork attachment, the fender could jam hard against the wheel, causing a bad crash. Some fenders sold today have this safety feature; probably all fenders should.

Here is some hardware for the 20" fenders I made. There is stainless steel plate (about .035) that I cut and drilled. 1/8 .035 stainless tubing goes thru it. It's silver soldered in place. Brass screws hold the fender on. The supports are not adjustable, but shouldn't need any adjustment. I could easily remelt and move the plate up or down the rod if I had to, however.

The tubing had a kerf cut at the end with an angle grinder fitted with a thin abrasive wheel. Then it was fitted over a tab of plate stainless steel, and silver soldered in place.

The wood is 3 thin layers of cedar, made the same way as the 16"fenders above. The fenders (hardware included) only weigh about 1/2 lb., and are very sturdy on the bike. They do not move, flex, or rattle.

To solder the stainless steel, all I used was 56% silver coil (1 oz. is about $22), silver flux, and a standard hardware store propane burner. Hardware stores also sell silver brazing packs that contain the flux and coil together, for fixing pots and pans and the like. Just heat it so the flux is clear before heating and applying the silver coil. Avoid getting the metal so hot that it is red, since the flux burns up if too hot, and the silver will not flow well. Practice on scrap first!

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