Rake & Trail Explained

A motorcycle rake (frame neck angle) is the fork angle measured from an imaginary 90 degree line. 
The rake of a bike has a direct influence on the trail. 

 Raked Trees 
I get lots of requests to put rake in the trees. Some people want to use them to extend their stock bikes.
The simple answer is if you want that extended look . . . consider, instead, raking your chassis by cutting your neck and positioning it for longer tubes, chopper style.

Both fork and, in the case of a springer front end, rocker offset also have a direct influence on the trail. 

Trail is the distance between where the projected steering axis hits the ground and where a vertical line down from the center of the front axle hits the ground.
Rake has a big influence on how the bike handles at different speeds and under different riding conditions.
Increasing rake will improve stability when riding in a straight line but an excessive rake can make bad handling in turns especially at low speed. 
Too little or too much trail create handling problems. 
©1999-2007 Jeri's Springer Front End. 1-727-449-2058 All rights reserved.
This diagram shows how both the fork offset and the rocker offset on my springer push the wheel forward thereby reducing the trail.
Too litte trail:
With negative or too little trail the bike will handle well at low speeds but will easily develop a dangerous wobble at high speed. 
Normal Trail:
The trail should be between 4 and 6.5 inches so that the bike handles easily at both high and low speeds.
Too much Trail:
You will have trouble balancing the bike at low speeds and it will handle sluggishly at high speeds. 
Raked Trees
Using "raked" trees will increase the angle of the forks by 3 (or whatever) degrees.

This is NOT the same as adding rake because the steering axis doesn't change. The result is that trail is DECREASED as the contact patch of the tire moves closer to the steering axis. This is OK if you have too much trail and want to decrease it. BUT raked trees can result in negative trail.

Raked triple trees are really for use where the bike has a regular glide font end and a neck rake angle of 40 degrees or more. In these cases raked trees can reduce the trail to a shorter, more manageable, distance. However too much rake in the trees will result in too little trail.
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