If you can use a saw and a drill then you can make this mud guard very easily. It takes only a few minutes to create something that looks professional and works well.
The brakes on my bike are Shimano SLX which I have added retainer bolts instead of cotter pins to keep the pads in place. you should be able to do this modification on any brake calliper which uses a central screw in retaining bolt to keep the pads in.
You can see the problem in the pictures - in one the calliper is clean and the other is dirty after a ride through miles of mud. The mud reduces the braking power by contaminating the pads and acting as a lubricant. That is also when you get squealing brakes.
The brake callipers and pads have an opening to them, for increased ventilation. In the wet , muddy cold winter conditions ventilation is not a problem but keeping the brake pads dry and clean is.
The mudguard woks by stopping rain and mud getting into the gap and therefore keeps the pads clean and dry.
You will need;
1. Two picture rail hooks (the type that is in the photo below which hang on a rail rather than get nailed into the wall)
2. Rotary tool with cutting disk (or hack saw)
3. File or sanding attachment for rotary tool
4. Drill with an assortment of metal drill bits
5. Safety gloves
6. Safety goggles
7. Screw in retaining bolt if you are converting from a cotter pin set up.
Before we get into the details of how to make this Instructable I have decided that this modification needs a name. "Brake calliper mud guard" is too boring. I am going to call it a "Picture Hook Anti Sludge Thingie" (PHAST). Clean dry brakes should give you greater confidence and make you faster anyway so this sounds appropriate. Anybody else got any better ideas?
LEGAL DISCLAIMER (well, I am a lawyer after all!): If you decide to do something similar to this to your bike you take full responsibility for any damage to yourself, the bike, any other person or any other property as a result of such a modification. Brakes are an essential safety item on your bike and you should not touch them or modify them unless you know what you are doing. Do not attempt this modification if you are not confident of your own mechanical skills. If in doubt speak to your local bike shop mechanic (who you should be supporting anyway).
Next repeat step two - after all, "measure twice and cut once" is a good maxim and avoids you cutting too short. If you want to you can bend the bottom of the tab so that it is straight, which will make it easier to cut.
Put on your gloves and safety goggles and cut the bottom off the hook "tab". Then check that you did measure correctly. I used a rotary tool with cutting disk but a hacksaw would also work. I cut from the inside just in case I slipped and marked the metal - if the mark is on the inside you can't see it but a big scratch on the outside would annoy me.
Step 2: File the Edges
Whilst I was there I also took the opportunity of rounded off the edges slightly as I thought it made the end product look that little bit more professional.
Step 3: Drill a Hole for the Retaining Bolt to Go Through
Drill a hole the same width as the bolt into the tab in the appropriate place.
I find it easier to make an indentation in the metal with a nail and a hammer as this stops the drill from moving around on the metal.
I also used a small drill bit to start with and then increased the drill bit size to make the hole bigger rather than starting off with the proper sized drill bit right from the off. I think that this gives better control and means that you are going to be more accurate.
Step 4: Install, Tighten and Adjust Mudguard
Put the mudguard onto the outside of the calliper and then slide the pad retaining bolt into the hole and through the calliper and the pads.
Tighten up the bolt which will trap the mud guard between the bolt and the calliper and hold it tight. You may also find, depending on the shape of your calliper that this bends the end of the mudguard slightly.
Adjust (bend or angle) the mudguard as necessary so that it is not touching the brake pads and allows the brakes to work correctly without interference from the guard.
Install the retaining pin on the other end of the pad retaining bolt.
As you can see from the pictures there is still plenty of space under the mudguard to allow air to cool the pads whilst the guard stops the rain and mud getting in. You may need to adjust the height to get the optimal balance between cooling and cover.
Step 5: Test
Spin the wheels of the bike and then test that the brakes still work.
Assuming that they do go for a low speed test run in a quiet traffic free area - again to make sure that your brakes still work.
Once you are satisfied that the brakes work go out and have fun and enjoy muddy rides with improved braking from quiet brakes and without fear of mud and stuff getting into your callipers.
In the summer when mud subsides and temperatures increase I would suggest taking the mud guard off to allow for maximum ventilation to the callipers.
Thanks for reading.