Bike Braking Systems Explained: Mechanical and Hydraulic Action
As mentioned in our previous blog post, disc brakes, having been somewhat of a novelty just a few years ago, are now a common sight - most high-end bikes are fitted with disc brakes rather than rim brakes, including our Abington and Rosemont town bikes. With better braking efficiency and durability, disc brakes come with a higher price tag than their rim-based counterpart.
Disc brakes are actioned using one of two main braking systems, mechanical and hydraulic, which have their own set of advantages and disadvantages. Mechanical braking systems use a lever paired to a metal cable attached to the pad - engaging the lever relies on the tensile strength of the cable to compress the pad against the rotor/rim. Meanwhile, hydraulic action uses pressurised fluid encased in a sealed cylinder to transfer the force as the brake lever is pulled and the fluid compressed.
The type of braking system fitted to an a bike is a critical specification and can have a drastic effect on the riding experience, so it is important to be aware of their advantages and disadvantages.
The main difference between the two systems is efficiency, with hydraulics outperforming mechanical. This is because in a mechanical braking system the cable will suffer from friction as it is pulled, so the transfer of energy is less complete and the force applied at the lever is going to be greater than the resulting force at the calliper. Meanwhile, as hydraulic brakes do not suffer from any wasteful friction, the force is transferred much more efficiently – in fact, it actually multiplies the amount of effort put into the lever so the braking force is greater than the force applied.
Hydraulic brakes are advantageous in other ways. For example, because they use a closed cylinder, dirt and mud can not get inside, making them essentially maintenance free. Meanwhile, grit can get into the mechanical system, which will affect braking performance - it is particularly noticeable in wet conditions that mechanical brakes struggle to match the efficiency of hydraulic systems. Mechanical brakes are also somewhat heavier than hydraulic brakes. However, it must be said that mechanical brakes are relatively easy to maintain with some simple cleaning methods, and when hydraulic brakes do go wrong, then it is a much more complicated fix. They are a more expensive option too.
Thankfully, the two systems need not be decided between, as hybrid brakes are available which marry many of their advantages. In such a system, a standard mechanical brake cable links the lever to a small arm on the caliper body, which then operates a hydraulic master cylinder piston. That piston pushes fluid through the body to the slave pistons, which then squeeze the pads against the rotor. As compared to purely mechanical disc brakes, the advantages of hybrid braking systems include increased power, a more responsive-feeling lever, and better resistance to weather and road grime.
Keep a lookout for future project developments - we are working on an exciting new set of brakes, which will be unveiled and available very soon.