When buying a second-hand bicycle or a new one with disc brakes, we sometimes don't pay attention to the type of actuation system they use. Are they mechanical brakes or hydraulic brakes? However, this aspect is very important for braking performance. Disc brakes have already become the reference standard for all types of bicycles, regardless of the discipline: mountain bike, road, cyclocross or gravel). That’s why, for your future purchase, it’s important to know the differences between a setup with hydraulic or mechanical disc brakes, since each has its own characteristics that end up affecting things like performance or maintenance.
➡️ Advantages and disadvantages of using disc brakes on the road
6 key differences between hydraulic and mechanical brakes
There are numerous differences between hydraulic and mechanical disc brakes for bicycles. Below we show those we consider most relevant when choosing one system over the other.
Actuation
Both systems have the same essential parts: lever, hose or cable housing, caliper, pads, and disc. But they differ in the technology used to function. In the mechanical brake, the force applied to the lever is transferred to one of the pads (not both) through a tensioned brake cable. In the hydraulic brake, the force the rider applies to the lever is transferred to the caliper pistons—and from there to both pads—via a fluid (mineral or synthetic oil, depending on the brake brand). Due to the pressure exerted by the fluid, the pads end up moving to squeeze the disc and thus stop the wheel from moving.
Braking behavior
2017/07/revisi%C3%B3n-frenos-disco-bicicleta.jpg"> The use of a cable or fluid to transfer energy through the braking circuit substantially changes the type of braking. A hydraulic disc brake will offer more linear and progressive braking behavior (from less to more).
The wheels will not lock up suddenly, reducing the risk of accidents or falls and allowing better control and handling of the bike. In contrast, a mechanical disc brake provides a more abrupt, less linear type of braking. The braking power may be greater at the very start of braking, but the rider has less room to modulate braking force according to their needs. On steep descents, for example, the mechanical brake is less effective than the hydraulic.
Performance in wet conditions
Related to performance, another major difference between hydraulic and mechanical brakes is their level of effectiveness in the rain. A situation in which good brakes are essential. On wet or slippery terrain, it's better to have hydraulic disc brakes, not only because they provide greater braking modulation. The circuit of a hydraulic disc brake is completely closed and more sealed against water entry. In mechanical disc brakes, the cable is exposed at its connection with the caliper. Thus, it is more likely that water will come into contact, enter the circuit, and alter its operation, reducing braking power and modulation.
Brake adjustment
Hydraulic disc brakes are self-adjusting in terms of power, modulation, etc., thanks to the properties of the brake fluid, which is responsible for their operation. On the other hand, a mechanical disc brake will require periodic adjustments to calibrate its power and modulation, by tightening or loosening the cable, as shown in this tutorial from Escuela de Mecánica de Bicicletas EMEB:
Remember that the adjustment of a mechanical disc brake is done on both pads, but separately. Only one of them receives the force from the lever through the cable, while the other is fixed and will require its own adjustment to be properly aligned with the other.
Disc brake maintenance
Hydraulic brakes are much easier to maintain and are more durable than mechanical ones. An annual system check and a circuit bleed, replacing the brake fluid with new fluid, will suffice. It is a somewhat more meticulous operation, but infrequent and it will increase the durability of the brake. You can see how it is done in this video:
Mechanical disc brakes, on the other hand, become misaligned more easily. They require more frequent, though simple, maintenance, very similar to classic rim brakes. In addition, their durability is more limited than hydraulic ones and the pads tend to wear out faster.
Price
Finally, one of the aspects in which both braking systems differ the most is price. A Shimano Deore group hydraulic disc brake kit costs around €60, while there are mechanical alternatives at half the price, for €30. Therefore, hydraulic disc brakes, although now widespread in all setups, are more typical of mid- and high-range models. Mechanical brakes, which were the first type of disc brake for bicycles to appear on the market, are limited to low-end models. However, it is no longer difficult to find affordable bikes that include hydraulic disc brakes, especially in mountain bikes.
Hydraulic or mechanical: which brakes should I choose?
Once we know all the characteristics and differences between hydraulic and mechanical brakes for cycling, it's time to choose the most suitable one, depending on your needs, skill level, the use you give to the bike, and the available budget. Mechanical disc brakes are suitable for beginner cyclists who go on short and easy rides, without too many technical sections. On the other hand, for someone who rides regularly and has a certain level, it is more advisable to buy a bicycle with hydraulic disc brakes, which are better suited for safely handling technical descents and obstacles in the case of mountain biking or cyclocross, or mountain pass descents in the case of road cycling.