Intro: Bike Fenders From Recycled Bike Tires
If you hate to throw stuff away, then you will loves this Instructable. As a pack rat, you must have a number of worn out bike tires with no way to use them and no way to get rid of them. The answer is to use them as fenders on your road or other narrow tired bike. Besides the tire all you will need are some zip-ties (or wire or string), some steel rod or tubing, and some ingenuity. The result will keep your face and blaster dry while splashing through puddles on your bike. Read on!
Step 1: Materials
You don't need many materials for this project. The basic materials are an old bike tire, preferrably a wider mountain bike tire with wire bead, some steel rod or tubing (copper or other metal OK as well), and a refusal to throw anything away and pay $15 for a set of Chinese made fenders.
Bicycle that you want to put fenders on
One worn out wire bead bike tire wider than those on your bike
Some steel (or other metal) rod or tubing
A welder or torch to solder with
Some zip ties
Some scrap steel or copper sheet (20 Ga or so)
A power drill
A metal file
Some spray paint
A method to cut your tire
Misc bolts and nuts to mount your fenders.
To start with, take your scrap tire and cut it into sections that cover the desired portions of your bike wheels. See below for an idea of how much coverage is needed to keep you dry.
Step 2: Front Tire: Step 1
From the pictures on the intro and this step you can get an idea of the scope of the project. You need to create some supports for the bike tire fender from metal rod or tubing that you can bolt to the various mounts on your bike. The wire bead in the bike tire will support itself over the rest of the span. Pictured below is the long arch that keeps the lower portion of the front fender from hitting the tire and the smaller saddle shaped piece bolts to the front brake caliper hole at the bottom of the head tube. Your bike may differ slightly but the general idea is the same: mount the fender to keep you dry.
To make the parts shown below you will need some metal rod and some scrap metal. First cut some tabs for bolting the large U-shaped part to the bottom holes on the front fork dropouts. Use a tin snips, and then drill holes in the tabs as needed. See pic.
When you have two tabs ready, bend a metal rod into a long U so that it will extend from your fork dropouts around your tire roughly parallel to the ground and will clear the tire easily. Trim the length of the U-rod so that it will fit correctly when installed. Then weld or solder on the tabs as pictured.
Once it is cool, test fit the loop by bolting it to the fork as pictured.
Step 3: Front Tire: Step 2
With the lower U loop finished, the next step is to make the upper mount that bolts to the caliper bolt at the top center of the fork. Take a short section of metal rod and bend it into an arch that matches the curve of the tire you are using for a fender and that will easily clear the tire on your bike. Then cut a tab that will hold this arch at the desired height above your tire when bolted to the caliper hole in the fork. You will have to measure your own bike and adjust as you see fit. The pic below shows the idea.
With the tab welded to the arch, double check your measurement and then drill a hole for mounting the arch. You will need to cut a slit in your fender-tire to push the tab through and then you can test fit the arch to make sure that everything fits right.
Step 4: Front Tire: Finish and Mount It
With both parts welded and test fit, the next step is to paint the metal so it won't rust. If you used copper this may not be needed. Once the paint is dry, you can mount the fender to your bike. The top arch and tab are bolted to the top of the fork at the brake caliper mounting hole. Nothing more is needed at the top. Make sure that the fender-tire does not interfere with brake operation. With caliper brakes you will most likely have to trim the fender so it remains behind the brakes. Cantilever and V type brakes have enough clearance so the fender-tire can extend through the brakes if desired.
At the bottom U loop, poke some holes in the fender tire where the loop crosses the bead so that you can push some wire or string or zip ties through the hole and attach the tire to the U loop. See attached pics.
Step 5: Rear Tire: Step 1
The fender for the rear tire can be very straightforward if you have a cargo rack. In my case I had a cargo rack that I built out of old steel brake line. If you have a steel rack, welding on additional hardware for the fender is simple. If you have an aluminum rack it can still be done but requires more specialized equipment (TIG). If you don't have a rack at all, you can make a U loop similar to the one used on the front tire and complete the rear fender without much trouble. Here I present my method which involved adding a rear arch to the back of my steel cargo rack, and using zip ties to attach the topof the fender-tire.
For the top of the rear fender, use a knife to cut a small slit in the fender-tire near the bead and at the point where the fender-tire crosses the rear seat-stay tubes. See the attached pics. Then the fender is held in place by threading zipties through the slits and tightening them around the seat stays. Easy as that.
Step 6: Rear Tire: Wrap Up
The back of the rear fender is held off the wheel by an arch welded between the rear supports of my steel cargo rack. This is simply another section of scrap steel tube bent to shape, with the ends pounded flat with a hammer, the paint wire-brushed off of the rack, and the arch welded in place. The rear fender just rests in place. In practice this works well.
Hopefully all this has made sense. Since each bike is a bit different and anyone considering this project probably has a well customized bike I hope the preceding serves as enough of a framework to allow others to adapt to their specific needs. Happy making! Feel free to contact me for clarification or questions.