Hydraulic Vs Mechanical Disc Brakes

HAMISH GLOVER WILSON - LANE BIKES

LANE eBikes are fitted with hydraulic disc brakes for the superior slowing and stopping power they offer, in this guide we look at what they are and how they compare to mechanical brakes.

The difference between disc brakes and rim brakes

All bike braking systems work by applying pressure to a surface on the wheel causing friction which slows the wheel. Rim brakes make contact with the rim of the wheel whilst disc brakes clamp around a disc or “rotor” which is fixed to the hub and spins with the wheel.

The rotor spins between the brake pads which are housed within the calipers so that when pressure is applied to the brake levers, the pads apply pressure to the spinning disk and slow the wheel.

The calipers on rim brakes reach around the tires so that the pads are adjacent to the rims of the wheel. In this set up, when pressure is applied to the lever, the pads close directly onto the rim to slow the wheel.

How do Hydraulic and Mechanical Disc Brakes differ?

The fundamental difference between mechanical and hydraulic braking systems is how the calipers are activated when pressure is applied to the brake lever. A mechanical steel cable vs. a hydraulic fluid-filled brake line.

Pressure applied to the lever of a hydraulic system activates a plunger to push hydraulic fluid along the brake line from the master cylinder. That pressure in turn activates a piston in the calipers to push the pads onto the rotor.

With a mechanical system however, pressure applied to the brake lever pulls on the steel cable. That cable is connected to a lever on the caliper which then activates a piston to close the pads over the rotor.

Pros and Cons

Hydraulic Disc Brakes

Pros

• More effective & more efficient stopping power

• Less frequent maintenance

• Sealed which keeps contaminants out so less cleaning is required.

• Smoother operation because there's less friction in the system.

• Better control of the braking force

• Lighter

• More consistent

• Less force to operate

• You can ride faster because you can stop faster

• More technologically advanced

Cons

• More expensive

• Specialty tools and fluid are required.

• More involved maintenance because you have to bleed the brake lines occasionally.

Mechanical Disc Brakes

Pros

• Cheaper

• Easier to repair and maintain because they are simpler

• You can easily service them in the field with basic tools

Cons

• Less stopping power and less efficient

• Require frequent adjustments as cables stretch

• Less control of braking force

• Friction in the brake cables can make them feel less smooth and less consistent

• More frequent cleaning as the cables can get contaminated with dirt or debris

• Heavier

• Slower to activate

• More force required to apply the brakes

• Pads are more likely to rub when they are out of adjustment

• Lower end and are less technologically advanced.

Hydraulic Vs Mechanical Disc Brakes

Stopping Power

The reason hydraulic systems are more efficient with a more effective stopping power is all down to using fluid instead of a cable. 

As the cable in mechanical systems is activated, some of the energy used to pull the lever is lost through friction as the cable passes through its housing and some energy is lost due to the cable stretching. The result is less force getting to the calipers than is being exerted on the lever by the rider.

Hydraulic fluid creates very little friction as it passes along the line and it cannot stretch or compress, resulting in minimal loss of the initial force exerted on the brake lever by the rider.

The result is a more powerful braking with less effort. 

Brake Maintenance

With no stretching cable to adjust, the only relatively regular maintenance required for a hydraulic system is replacing the pads as the wear out.

The consistent pressure of a hydraulic disc brake system even keeps brake pad alignment regulated as they wear down, there’s no stretching cable or adjusters which mitigates against uneven pad wear.

Hydraulic systems will need to be bled approximately every 2-3 years which consists of replacing the brake fluid. It does require specialized knowledge and tools, and is maybe a job for a bike mechanic.

In comparison, mechanical brakes require regular maintenance to account for wearing pads, stretching cables and pad mis-alignment. Cable housing can become contaminated with dirt and debris which can result in the lever becoming snagged and the braking less efficient.

One positive is that the tools and knowledge required for maintaining mechanical braking systems are much less sophisticated.

Modulation of Braking

So little effort is required to operate hydraulic brakes which means that it's easier to modulate how much braking force is being applied by the pads onto the disk. This sensitivity means greater control over braking force which ultimately leads to safer braking and less skidding.

The less controlled braking that comes with a mechanical system can lead to less accurate pressure being applied to the pads and therefore less efficient ride and potentially more likely hood of wheels locking-up.

Weight

With fewer moving parts, hydraulic systems are lighter than mechanical. There’s not a huge difference, but in scenarios where weight is a consideration, such as racing or keeping an eBike as light as possible, a hydraulic system is preferred.

Smoothness of Braking 

Having no cable to get snagged or produce friction as it operates means that hydraulic brakes produce a very smooth braking sensation in comparison to mechanical brakes. The sealed system prevents contamination and provides predictable and consistent activation.

Speed

Hydraulic disc brakes are fitted on LANE eBikes because they reduce the stopping distance and so provide confidence to ride at speed safely. Being able to stop faster with increased braking efficiency leads to faster average journey times.

Hand Comfort

Hydraulic system brake levers are so sensitive they require very little effort to activate them which makes them more comfortable to use than mechanical brakes.

Mechanical brakes have to be squeezed with a fair amount of force in order to activate them and over a prolonged journey, or with frequent use over a short period this can lead to fatigue or straining of the hand. 

Disc Brake Technology

At the time of writing this guide, hydraulic disc brakes are the most advanced braking systems in use. The heightened performance means that they are the braking technology of choice for competition bike manufacturers.

Some mechanical disk brake systems are high performance with comparable stopping power to hydraulic systems. However, often  manufacturers of lower-end bikes will use poor quality mechanical disk brakes in order to give the impression of a premium bike and the stopping power is no better than that of a rim brake system.

Other considerations for stopping your bike

Rotors

Rotors can come in a range of sizes from 120mm-205mm and as a rule, the larger the rotor, the better the stopping power. Some more serious riders will elect to have a larger front rotor as that is the one that will produce most of the stopping power, but on the whole the rotors will be the same size front and back. 

Tires

Tires play a significant role in bringing a bike to a stop, after all, they are the only part of the bike in contact with the road. Any modern brake system will have the power to stop the wheels from spinning, but it’s the friction between tire and road that will stop bike and rider from moving forward.

Narrow tires have less material in contact with the surface of the road, so will produce less friction when the wheels slow and will therefore not stop as fast as a wider tire. However, the pay off is that wider tires are heavier, less energy efficient and produce more noise whilst riding.

Whatever the width of tire, the tread is a critical element to slowing the bike and in order to maintain traction and to achieve optimum performance from brakes and tires.

The Express eBike from LANE Bikes is fitted with Tektro HD-E350 hydraulic disc brakes and 180mm rotors.
The Express is a commuter bike which can mean a lot of stopping and starting which puts a great deal of stress on the braking system. With so much high energy braking, the cable of a mechanical system would require weekly adjustments.

Fitting The Express with a hydraulic disc brake system minimizes that maintenance and the huge rotors increase the stopping power meaning that the Kenda K1053, 700 x 32C puncture resistant hybrid tires transfer substantial braking without having to compromise on weight or efficiency with a thicker tire.