DIY Bicycle Mudguards / Fenders

It's been raining so much, it was time to put mudguards on the bike. These aren't your standard mudguard design, so I tested them out and they work well.

There's also a video of the build and shows them being tested at the end.

• 4 x M4 12mm bolts with nylock lock nuts and washers 
• Aluminium flat bar 12mm x 3mm approx. 3.2 metres (length may vary for wheel size)
• Aluminium flat bar 25mm x 1.6mm approx. 2.3 metres. This is for narrow road bike tyres. Use a wider flat bar for larger tyres. (length may vary for wheel size)
• 6 x Pop-rivets or you could use bolts for these too.
• Hacksaw to cut aluminium bar
• Vice to bend aluminium bar
• File and sandpaper to smooth edges and corners of aluminium

For the build, the first step is to measure how long the mudguard should be. This will depend on your wheel and tyre size.

As a guide, the mudguard should extend around to the 3 o'clock position on the wheel.

Cut a length of aluminium flat bar. I used 25mm by 1.6mm, but I think 3mm thick might be good too. It would certainly be a bit tougher. This is for narrow road bike tyres. Use a wider flat bar for larger tyres, if you do use a wider size, 1.6mm is probably thick enough.

Do a test fit checking there's enough clearance between the tyre and brakes.

File and sand mudguard ends so they're not catchy.

Next is to make the bracket that attaches the guard to the brakes bolt and forks.

While test fitting the guard in Step 1, mark the position of the bracket.

Measure the height of the bracket, add 1 inch and cut another piece of flat for the bracket. Bend it using a vice and a piece of wood at the 1 inch mark. Then drill 2 holes and attach the 1 inch side with 2 pop rivets at the position you marked on the guard.

Double check the size of the brake bolt and exact position for the hole on the bracket. Drill this hole in the bracket. I always use a smaller pilot hole first for accuracy.

Fit the guard with bracket to the bike, and check the clearance.

Measure the length for the stays from the mudguard fixing on the bike frame, ensuring you leave a good amount of clearance between the tyre and the guard. Then add some extra for the width of the tyre, we're going to bend a U shape.

I added 44mm for the width of my tyre but this will depend on your tyre width.

Cut a length of aluminium flat bar, 12mm by 3mm. Mark the middle and the bend points either side of the middle (they'll be 44mm apart).

Then bend the bar to about 80 degrees on each side.  

Mark the position of the first hole then attach it to the bike with a bolt before marking the position for the hole on the other side.

Hold the stay dead centre when marking the second hole so the stay is evenly positioned either side of the tyre.

Bolt the first stay to the bike and check the alignment and clearance.

All mudguards should have at least 2 stays to hold the guard securely. Follow the same steps for the second stay but make sure you re-measure the length for each stay as the stays will be different lengths.

Attach the guard to the stays so they're evenly spaced using the M4 nuts and bolts. Drill a 4mm hole through the guard and the stay. Use lock nuts and washers to make sure they don't come loose.

The steps for the rear are very similar to the front mudguard, with the main difference being an extra bracket to attach to the frame.

Measure up the length of the rear guard. As a guide, the mudguard should extend around to the 3 o'clock position on the wheel. I probably went a bit too long, but see what you think.

Cut a length of aluminium flat bar. I used 25mm by 1.6mm, but I think 3mm thick might be good too. It would certainly be a bit tougher. This is for narrow road bike tyres. Use a wider flat bar for larger tyres, if you do use a wider size, 1.6mm is probably thick enough.

Do a test fit checking there's enough clearance between the tyre and brakes.

File and sand mudguard ends so they're not catchy.

For the rear guard it has a hook to attach the end to the bike. Make another bracket for this and attach to the guard using 2 pop rivets.

Follow Step 2 instructions and make another bracket for the brake and attach it all to the bike.

Follow Step 3 to make 2 more stays for the rear.

Then bolt together as in Step 4 and good to go!