Bike Disc Brake, Hydraulic or Cable?

Here at Cycle Maintenance Academy we get lots of questions about bicycle maintenance and one of the main things we get asked about is disk brakes. Understanding basic cycle maintenance is a useful skill to have, not to mention the fact it can save you a lot of money. When it comes to bike tyres and your bike disc brake, keeping them well maintained is essential if you want to get the most out of your bike.

In this article we wanted to cover your bike disc brake to answer as many frequently asked questions as possible. We hope this manages to help, but if not please do not hesitate to let us know if you have any other questions and our friendly team of cycling maintenance enthusiasts will be happy to help.

Why does a bike have disc brakes?

There are two main reasons for that you have a bike disc brake. Firstly, to make the pads last longer. The rim brake pad is made of rubber, a bike disc break pad is made out of metal which is much tougher and more resilient. This stops the rims from wearing out. The braking surface is on the rotor located on the hub, the rims aren’t constantly being worn away as they are with rim brakes.

What are the two bike disk brakes?

The two types of bike disc brakes are hydraulic and cable. To identify which disk brake your bike has look for a cable sticking out at the end, if there is then you have a cable disk brake. You will be able to see the cable moving and operating the calliper by squeezing the lever. The bike disc brake without a cable is called hydraulic. Hydraulic disk brakes operate by compressing fluid. If you squeeze the hydraulic bike disc brake lever you will only be able to see the pads moving and not the calliper.

Does your brake lever have a barrel adjuster?

On a cable bike disc brake lever, where the outer cable joins, there is one. This can be used to adjust the brake. There is a lesson on how to do this in our cycle maintenance basics course. 

Hydraulic disc brake levers don’t have a barrel adjuster. Where the hose joins the brake lever, there is a plastic cover, and underneath this is a screw with a hexagonal top tightened into the reservoir. Don’t adjust this screw even if your brake feels loose, you might damage the lever and lose fluid. It is how they operate which tells us which is which.

How does a cable bike disc brake work? 

As you apply the lever on the handlebars, a cable inside the lever pulls against the brake calliper which pushes the pad against the rotor. When the lever is released it retracts and the pad on the other side is static.

When there is a rotor between the pads, the moving pad hits the rotor, this flexes and touches the static pad. This means that both pads are touching the rotor so the brake can work. One end of the cable is held in the lever, the other end passes through the plastic outer casing and into the brake caliper. it finishes after it has passed through the cable pinch bolt.  There should be a little lump of metal on the end of the cable.  This is to stop it fraying. If you have a piece of cable showing at the end of your brake caliper then you have a cable disc brake. On the lever, where the outer cable joins, there is a barrel adjuster. This can be used to tighten the brake. There is a lesson on how to do this in our basic maintenance course.

How does a hydraulic bike disc brake work?

As you apply the lever on the handlebars, fluid inside the lever is pushed through the hose, into the calliper and behind the pistons. This forces the pads to push out until they hit the rotor and subsequently stop the bike. The hose that joins the lever and the calliper looks very similar to the cable outer casing, but when it joins the calliper, there is no cable protruding and it is completely sealed so that the fluid doesn’t escape. If you can’t see a cable then you have a hydraulic brake. Where the hose joins the lever, there is a plastic cover, and underneath this a screw with a hexagonal top. Although this may look like a barrel adjuster it is not. It is tightened into the calliper and holds the fluid in place. If your brake feels loose, don’t adjust this screw. It won’t tighten your brake.

Overview of everything you need to know about you bike disc brake:

We hope this article has managed to answer all of your questions and queries regarding your bike disc brake. If there is anything else you want to know, please do not hesitate to contact us, we’re more than happy to help. One other frequently asked question we get asked is ‘how to stop bike disc brakes from squeaking‘ which you can find out in a previous article.

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