Cardboard Bike Fenders. Price: FREE

It’s the rainy season here in San Francisco. It may not rain much, but one unprepared rainy day can spoil the fun of a bike commute.

You may think a little water on the road from a morning rain won’t be a problem, but as soon as you get some speed, you notice spatters of water coming off the bottom of your front wheel straight up in your face! Later that day, a friend asks you if you forgot to wash your shirt, because you have a gnarly stripe of dirt on the back of it.

Looks like you’re going to need some fenders for your bicycle. Also known as mudguards or mudflaps. If you’re looking for other rain gear, you may like the Ultimate Rain Gear Guide.

Rear fender

This will protect you from getting the infamous stripe up your back.

If you don’t have a rear rack, I suggest you go with something easy and light like this fender. It’s easy to add and remove without tools, so on dry days there’s no need to bring it with you.

I attempted to install this on my bike, but I have a rear rack that prevents it from fitting properly. My bike is also older, leaving little room to buy a proper fender, so I decided to go with some functional fenders made out of cardboard and zip ties! Cardboard bike fenders!

Multiple benefits include:

  1. Your bike doesn’t look as cool anymore so thieves may not go for it
  2. Contrary to intuition, cardboard will not disintegrate in the rain.
  3. You can rip them off when the rainy season is over
  4. Obviously they protect you from the rain on the street
  5. Lots of compliments on your DIY skills
A cardboard box, a few zip ties, and some scissors can give you this stylish fender in minutes.

I cut out the edges of the cardboard so I could fit my rack bag like so.

My rack bag fits perfectly with my custom fender design. If you’re interested in the rest of the gear on this photo, check out my rack & bag

Many people think cardboard will fall apart when it gets wet. This is not true. It may get soggy, but it would take an entire season of being left in the rain before it falls apart on its own. As long as you leave it alone, it will dry to the same level of strength. At the time of these photos being taken I have had the fenders on for about 3 months and biked through at least 5-10 bigger rainstorms where the cardboard was completely soaked through (and still a functional fender). As long as you don’t mess with them while wet, the cardboard will dry and continue to do its job.

Front Fender

This will protect you from water flying up in your face. If you want to take the easy Amazon approach, you can try this one (check your fork style) or this one (which we’ll be recreating in cardboard!). There are better fenders you can buy that protect you more, but I haven’t tried them out yet since they’re a bit harder to install. I’ll update if I do.

After such great success with a rear fender, I decided to go with the same approach for the front fender. The front fender is not quite as elegant, but it does the trick. I had gearing cables running below my tube, so I put the cardboard above the tube. If you don’t have cables underneath, it might be easier to put it on the other side.

I don’t have a water bottle holder either. If you do, you could easily take it off and put the cardboard underneath it when you screw it back on. This will keep it from rotating side to side.

Surprisingly, my legs and feet don’t touch it at all, so no problems there!
Rounded edges for extra design flair.

When it’s not actively raining, I can push it to the side so it’s a little more out of the way.

One caveat about this front fender, it does not protect your shoes and ankles. If you have nicer shoes that you don’t want getting splashed, a proper front fender that goes further down closer to the wheel may be better suited for you.

Other DIY options

If you search the internet for a while, you’ll come across many different DIY fender options. Here are a few that I thought stood out, they’re much more serious and may require more tools than the cardboard + ziptie approach.

Bike fender out of detergent bottle:

Seriously nice DIY bike fender guide:

Stay dry!

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