Bike Wander
#23
05-09-2013, 04:56 AM
Join Date: Apr 2013
Location: Barrie Ontario Canada
Posts: 128
Thanks! Ya I`ll look at tires next season...I don`t mind burning these off. I DID pay for them after all... 
#25
05-09-2013, 03:19 PM
First generation (2006-2007) Rake/Trail 26.5°/4.2 in.
Second generation (2009-present) Rake/Trail 27.5°/4.3 in.
kLX250SF MODEL (2009-present) Rake/Trail 25.5°, 2.9 in.
To better understand this, visualize a motorcycle with 0 degrees of rake, with the forks straight up and down, perpendicular to the ground. Ride something like that much over walking speed and you’ll be introducing your face to the ground. Now consider the other extreme; forks kicked out like those of an early ’60s chopper. These bikes were stable at speed, but required a couple of ZIP codes worth of territory in order to make a U-turn. Additionally, at low speeds it’s difficult to keep these motorcycles upright as all they want to do is flop on their side.
Understanding trail is a little less easy. Imagine aiming a laser beam down through the center of the steering head, keeping its angle parallel to the steering head. Where the laser beam hits the ground, mark as A. Now, hold your laser directly above the centerline of the front axle, keeping the beam perpendicular to the ground. Where the beam hits the ground, mark as B. Measure the distance between A and B; that is trail. On the Harley Tourers, that measurement is 6.2 inches.
Now a little bit of the “why?” To achieve stability at speed, balance, and lightness of steering effort, a compromise between rake and trail is engineered into the chassis. For example, while those wildly raked forks might give excellent high-speed stability they are impractical for normal use. To maintain good stability and proper handling with the fork angle being in the normal range (from about 22 degrees to about 32 degrees) a certain amount of trail is designed in. Generally—again, there are exceptions—the more trail a motorcycle has, the more stable it is. However, increase the trail by too much and you’re back to chopper-like handling. Conversely, too little trail and the motorcycle’s stability begins to be adversely affected.
Achieving stability, lightness, and balance is a serious engineering problem, and we have only touched on the barest of its essentials here. If you’d like to know more about this subject (and you’re up on your trigonometry skills) you couldn’t do better than to pick up a copy of Motorcycle Handling and Chassis Design: The Art and Science by Tony Foale. This is the bible on the subject. A Google search will tell you how to find it.
Second generation (2009-present) Rake/Trail 27.5°/4.3 in.
kLX250SF MODEL (2009-present) Rake/Trail 25.5°, 2.9 in.
To better understand this, visualize a motorcycle with 0 degrees of rake, with the forks straight up and down, perpendicular to the ground. Ride something like that much over walking speed and you’ll be introducing your face to the ground. Now consider the other extreme; forks kicked out like those of an early ’60s chopper. These bikes were stable at speed, but required a couple of ZIP codes worth of territory in order to make a U-turn. Additionally, at low speeds it’s difficult to keep these motorcycles upright as all they want to do is flop on their side.
Understanding trail is a little less easy. Imagine aiming a laser beam down through the center of the steering head, keeping its angle parallel to the steering head. Where the laser beam hits the ground, mark as A. Now, hold your laser directly above the centerline of the front axle, keeping the beam perpendicular to the ground. Where the beam hits the ground, mark as B. Measure the distance between A and B; that is trail. On the Harley Tourers, that measurement is 6.2 inches.
Now a little bit of the “why?” To achieve stability at speed, balance, and lightness of steering effort, a compromise between rake and trail is engineered into the chassis. For example, while those wildly raked forks might give excellent high-speed stability they are impractical for normal use. To maintain good stability and proper handling with the fork angle being in the normal range (from about 22 degrees to about 32 degrees) a certain amount of trail is designed in. Generally—again, there are exceptions—the more trail a motorcycle has, the more stable it is. However, increase the trail by too much and you’re back to chopper-like handling. Conversely, too little trail and the motorcycle’s stability begins to be adversely affected.
Achieving stability, lightness, and balance is a serious engineering problem, and we have only touched on the barest of its essentials here. If you’d like to know more about this subject (and you’re up on your trigonometry skills) you couldn’t do better than to pick up a copy of Motorcycle Handling and Chassis Design: The Art and Science by Tony Foale. This is the bible on the subject. A Google search will tell you how to find it.
Last edited by zippets; 05-09-2013 at 03:24 PM.
