Bicycle brake systems

Early bicycles such as the high wheeled penny-farthing bikes had no brakes as we would recognise them. A rider who wanted to stop had to jump off the bike as it was moving. Unsurprisingly there were many accidents, many of them fatal, which limited the appeal of cycling, mostly to young and adventurous men.

The 1870s saw the development of the "safety bicycle" which was roughly the bicycle we would recognize today, with two wheels of equal size, driven by a chain, with pneumatic tyress.

The braking system these bicycles used was often a simple leather pad which pressed against the top of the tyre, which was driven by a rod attached to a lever on the handlebar, and there was no rear brake. This was undoubtedly a big improvement on having no brakes at all, but it was not very powerful and had the big drawback that it was almost useless in wet weather.

After that the next big advance in bicycle braking, which came around the 1890s, was the invention of the rim brake. This is the type of brake most commonly used on bicycles today.

Rim brakes

Rim brakes, as has already been mentioned, are the most common type of bicycle brake in use today. Essentially they use two pads (usually made of leather or rubber) to press in a scissor-like fashion against the side of the rims, thus causing friction and slowing or stopping the bike. The power of the braking depends on how hard the pads push against the rims.

This force is applied by the rider squeezing a lever mounted on the handlebar, and transfered to the brake by means of a cable, or sometimes a rod. There are several different designs of rim brakes, with the most modern being the cantilever and V-brake, both of which are very powerful. More traditional caliper brakes are still found on many road bikes.

The advantage of rim brakes is that they are cheap, lightweight, mechanically simple and easy to maintain. Also, modern designs of rim brakes are very powerful.

One major disadvantage of rim brakes is that they need regular maintenance. Brake pads wear down frequently due to friction against the rim, and therefore they have to be replaced at regular intervals. Also, if used over long periods of time, rims also wear out due to friction and have to be replaced.

The other main disadvantage of rim brakes is that their performance deteriorates in wet weather when the rims are wet, although this problem is far less serious on bikes which use rims made of Aluminium alloy. They are also prone to clogging with mud when mountain biking in wet conditions.

Disk brakes

This type of brake is most suitable for and found mainly on mountain bikes which are ridden off road.

Although this type of brake has been used on motorbikes for decades, only recently have they been added to bicycles. This type of brake works in a similar way to rim brakes, but it is far more powerful and reliable. Basically a disk brake consists of a metal disk attached to the wheel axle between the spokes and the fork, there is a brake pad mounted near the bottom of the fork (the bit which the wheel is attached to), which presses against the disk when a cable is pulled by the rider, which stops the bike.

One advantage of this setup over a rim brake is that a far larger pad can be fitted, because on rim brakes the size of the pad is limited by the narrowness of the wheel rim. The large pads used on disk brakes are less affected by mud and water which means they will work well in all weather conditions. On some expensive disk brake models, a Hydraulic system is used to push the pad instead of a cable.

Another advantage of disk brakes is that they are very powerful and, as mentioned before, their performance is equally good in all conditions. They also avoid the problem that rim brakes have of wearing out the wheel rims. They are generally easier to maintain than rim brakes too.

On the down side, however, they are heavier and more expensive than rim brakes.

Hub brakes

Hub brakes are brakes that have their mechanism enclosed within the hub of the wheel, and are usually fitted to the back wheel. They are drum brakes which are the type of brake used on carss. Because they are enclosed, hub brakes are completely unaffected by the weather. Some types of hub brake are operated by cables and levers, in the same way as rim and disk brakes. Other types are operated by the rider turning the pedals backwards, these are known as "back pedalling brakes", or "coaster brakes".

In addition to being impervious to changes in the weather, hub brakes have the advantage of needing very little regular maintenance, especially the back pedalling type.

On the downside, when hub brakes do require maintenance it is far more complicated than other braking systems. They occasionally need to be dismantled and re-greased, usually by a professional. Also hub brakes are heavier than all the other types of bicycle brake.

Hub brakes are used mainly on utility bikes

One handed brakes

One-handed bicycle brakes are a relatively new invention. (See http://www.brakedirector.com for a picture.) They work by providing pressure on the back wheel first, then the front wheel. This provides for a smooth and complete stop.

This kind of braking system is ideal for those who do not have use of both hands, and it works well on paved surfaces.

It is not meant for mountain biking or trick riding - those types of riding require finer control over braking.

Braking technique

Effective use of a bicycle brake is highly counter-intuitive. Simply put, the most important rule is: use the front brake almost exclusively.

During braking (either with the front or rear brake), most of the cyclist's weight is transferred to the front wheel, leaving the rear wheel with almost no force keeping it pressed against the ground. Thus rear brake, especially in wet conditions or going downhill, can exert little braking force before the wheel locks and starts skidding. A skidding rear wheel can lead to dangerous, uncontrollable bicycle movements eventually resulting in the cyclist falling on the ground.

Also, the rear brake can only produce a fraction of the braking force easily provided by the front brake. In emergency situations, it is important to grab the front brake and press it as hard as one can to stop in the minimum possible distance.

The casual rider will at first avoid using the front brake, due to the unsettling feeling of "toppling up". It is important to explain the issue and invite the rider to give both brakes a few tries, simulating an emergency situation. Also note that it is almost impossible to actually lock the front wheel.

There are a few special situation where limited use of the front brake, and heavier involvement of the rear brake is advisable: on extremely slippery surfaces, like mud, snow or ice. But this should be considered the exception and not the rule.

External links

• Bicycle Repair: Adjusting brakes