Trail braking

Trail braking is a motorcycle riding and driving technique where the brakes are used beyond the entrance to a turn and are gradually released up to the point of apex.

Usage in motorcycling

In applying this technique, motorcycle riders approach turns applying both front and rear brakes to reduce speed. As they enter the turn, they partially release the brakes, as to keep only partial brakes throughout the turn. This will give more traction as the front tire is forced into the pavement.

This technique is commonly used when racing, but can enhance control and add more evasive options for street riders making it very worthwhile to learn or at least understand.

Be aware though that excessive trail braking can result in a loss of grip as the tire's adhesion is split between braking and cornering forces. It will also noticeably affect the motorcycle behaviour (as in handling). Should the surface traction be unexpectedly impaired, possibly by oil or fuel spills, a crash is utterly unavoidable.

For a discussion of how this applies more force to the front tire and how much, see Bicycle and motorcycle dynamics.

Usage in four wheel vehicles

In 4-wheel vehicles trail braking pertains to using the brakes past the corner entrance (as opposed to the normally taught practice of releasing the brakes before starting the turn). This practice is used for creating weight transfer towards the front tires, thus increasing their traction and reducing understeer. It works best in light vehicles that have their brake bias to the front.

In order to be properly performed, the driver must have excellent sense of the vehicle's behavior and be able to keep the braking effort within very tight limits. Excessive braking effort may result in the vehicle heavily understeering, or - if the brake bias is set to nearly neutral - in the rear wheels locking, effectively causing the vehicle to spin as in a handbrake turn.

Once a driver has mastered trail braking, it can help enter the corners at higher speeds, or avoid an accident if the driver has entered a corner at a speed exceeding the vehicle's (or driver's) capabilities.

Usage in racing

A drift-inducing technique called "the brake drift" is used in racing, involving a series of light trail-braking pulses (usually 2 or 3), followed by a momentary full-force braking and sharp releasing of the brakes. Mastering continuous trail braking as used under road conditions is a prerequisite for learning brake drifting. This is one of the most used drifting techniques in rally racing because - if done properly - allows the driver to enter and exit the corner with full throttle.

Depending upon cornering situations, techniques like trail braking can be used to maintain more speed upon entry of a corner, and attaining more grip while turning into the corner, and has an effect on apex selection. In this technique, brake pressure is applied slightly later than usual upon deceleration, and is maintained during steering input, sometimes all the way to the apex. The action of braking causes a weight transfer in the vehicle, shifting more weight from the rear of the car forward to the front tires, increasing the normal force on them and in turn increasing the amount of traction the front (steering) wheels have. Because of the characteristics of weight transfer, this technique causes weight to be shifted away from the rear of the car, resulting in lower rear traction, and can be used to induce oversteer in some cases.

References

*cite book
author=Ienatsch, Nick
title=Sport Riding Techniques: How to Develop Real World Skills for Speed, Safety and Confidence on the Street and Track
publisher=David Bull
year=2003
id=ISBN 1-893618-07-2

*cite web
url = http://virtualracersedge.com/trail_braking.htm
title = Physics of Racing -- Trail Braking
author = Brian Beckman Ph. D
accessdate = 2006-12-31

External links

*Video Footage of [http://www.karting1.co.uk/braking-karting.htm Trail Braking with a Kart]