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View Full Version : MotoGP Basics ~ Brakes



Hellraiser
06-12-2010, 11:07 PM
Motorcycles must have a minimum of one brake on each wheel that is independently operated. In the 125cc and Moto2 classes, only brake discs of ferrous materials are allowed. In the MotoGP class, carbon brake discs may be a maximum diameter of 320mm.
A reliable set of brakes comes in handy when you are trying to win a race on a bike which can travel at speeds in excess of 340 km/h.
While tyres change from session to session, brakes can be replaced if they are damaged or become wet - though they are more permanent elements of a riders armoury and are just as important in allowing him to take corners at the optimum speed and angle.
Braking patterns, in equal measure to pure acceleration, dictate how races are won and lost as a rider’s skill and the reliability of his brakes allow him to run the fastest ‘race line’ and outmanoeuvre his opponents.

CORNER SPEEDS

Evermore so in the new era of 800cc machinery, corner speeds are crucial to success in MotoGP. If a rider can apply his brakes later and at a higher speed than his fellow competitors he can overtake those in front of him and lap quicker than the rest of the grid.
The front end brakes do most of the ‘stopping’ work, with riders controlling their cornering mainly through the leading tyre and as much as 90% of the bike’s weight transferred through the front wheel as its brakes are applied. Therefore it is not uncommon to see the back wheel leave the ground (fish-tailing) and the rear wheel and brakes do much less to guide the bike while the front brake is being used.

CARBON OR STEEL

MotoGP teams use disc brakes on their racebikes, technology which first emerged in the 1970s and has been in development ever since. Early versions of these discs were steel only and did not work very well in rainy conditions, but were later developed to produce progressive braking in both the wet and the dry.
Now, conversely, steel disc brakes are used by MotoGP teams only in the wet as they have a more modern and efficient solution to be used on dry tracks – carbon brakes.
The benefit of carbon discs are that they weigh 750g to 800g for the same diameter as their 1,200g to 1,600g steel discs counterparts. These figures may seem trivial but where cutting edge racing technology is concerned the half kilos soon add up.
Disc brakes consist of a disc which is mounted on the wheel and calipers which are fork mounted and carry the pads. The pads make contact with the discs and slow the rotation of the wheel when the rider applies the brakes. The rider operates the brakes via a standard handlebar mounted lever, but foot or left thumb controlled rear brakes are also used.

WEIGHT SAVING

With carbon brakes, the discs, calipers and pads are all lighter and twin disc systems, with a disc on each side of the wheel, are common – so in total carbon discs can save more than two kilos overall.
Less weight means less inertia, which reduces the ‘gyroscopic’ effect that can counteract the rider's efforts to get the bike to change direction. This essentially means carbon discs make it easier to change direction as the wheel, particularly the front wheel, is lighter when it has carbon brakes fitted.
Carbon discs can also offer a slight improvement in braking performance and consistency compared to steel systems. Once they reach optimum braking temperature carbon system should feel the same to the rider on lap 25 as it does on lap 2, but with steel discs the feeling the rider has changes over the course of a race.
Although the lighter carbon discs are therefore preferable to their steel alternatives when they are working correctly, they are far more temperature sensitive. Their functionality is virtually nonexistent until the discs and pads are heated to their premium operating temperature, and while they heat up quickly, rider caution is required during sighting and warm-up laps, and even the first couple of corners in a race.

WEATHER

If the weather is dry and cold, or if the bike is being used on a faster tracks, where the brakes are not applied regularly, the discs can be cooled considerably by airflow so heat shrouds can be fitted to help them maintain heat levels.
But with water involved it is a different story, as carbon discs will not reach their operating temperature and will therefore cease to function correctly in wet conditions.
The solution in this instance is to resort to steel discs and this also requires different calipers and pads which means more weight - and alterations to the bike have to made in a time pressured period so the parts have to be easily detachable.
Carbon brakes are not cheap, mainly because they take from three to six months to make as they have to be ‘cooked’ and constructed slowly - which combined with their limitations in the rain means they are rarely used on production road bikes.

FRICTION

The only way to achieve maximum braking and turning efficiency is to couple the work of the discs with friction. Upon applying the brakes, the tyre is pressed against the track, effectively increasing the area in contact with the asphalt and in turn increasing the amount of friction or stopping force which is being applied. If the rider can do this late in the corner, as close to the apex as possible, he spends less time slowing down and reaches the point where he can accelerate out of the corner more quickly than his opponents.

MANUFACTURERS

The brakes used in MotoGP are produced by two companies, Brembo and Nissin, and each set of disc brakes costs several thousand euros. Fortunately for MotoGP teams a bike may only require six to eight carbon discs per season.