![]() For example, while those wildly raked forks might give excellent high-speed stability they are impractical for normal use. 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. On the Harley Tourers, that measurement is 6.2 inches. Measure the distance between A and B that is trail. Where the beam hits the ground, mark as B. Now, hold your laser directly above the centerline of the front axle, keeping the beam perpendicular to the ground. Where the laser beam hits the ground, mark as A. Imagine aiming a laser beam down through the center of the steering head, keeping its angle parallel to the steering head. Understanding trail is a little less easy. Additionally, at low speeds it’s difficult to keep these motorcycles upright as all they want to do is flop on their side. These bikes were stable at speed, but required a couple of ZIP codes worth of territory in order to make a U-turn. Now consider the other extreme forks kicked out like those of an early ’60s chopper. Ride something like that much over walking speed and you’ll be introducing your face to the ground. To better understand this, visualize a motorcycle with 0 degrees of rake, with the forks straight up and down, perpendicular to the ground. Generally speaking (meaning there are exceptions) the greater the rake angle, the more stable the motorcycle is at higher speeds. For example, the rake angle on all the Harley-Davidson Touring models is 26 degrees. Rake is the angle, in degrees, that the steering head of the frame-not the forks-is tilted back from the vertical. Rake is often called fork angle, but that is a misnomer. However, to understand trail, first you need know about rake. I mention this because the subject is a multi-faceted one, and we’re just going to focus on the single aspect prompting Izzo’s question. This is particularly so with competition motorcycles, but these factors also come into play with standard street motorcycles, just to a lesser degree. Contact us for questions and scheduling.Motorcycle suspension systems can be very complex, and involve numerous variables such as wheelbase, weight, ride height, tire size, suspension sag, and engine placement, in addition to rake and trail. On average, riders will see a drop of 2 to 4 seconds after setup. You can then apply these changes to the motorcycle giving you the proper geometry setup based on your riding skill/style, frame anomalies, tire manufacture and size, suspension components etc. Using the system, we are able to simulate changes to the bike to see how they affect the geometry stance. Only then do we have a complete “snapshot” of your bike’s stance and are ready to start optimizing your geometry. This allows us to consider any anomalies in your frame during the setup process. Once measured, we verify your frame to the system’s database of over 1500 chassis. These measurements are given in tenths of a millimeter and tenths of a degree and include: ![]() ![]() Based on an infrared camera system, the CMS provides a highly repeatable platform to retrieve key frame and geometric values to evaluate your bikes handling characteristics. The Scheibner CMS offers an excellent option to evaluate geometry for both racing and track day purposes. Scheibner CMS (Chassis Optimization System) – $350 Together with your riding style and the Scheibner, we will create a formidable race bike to get you on the podium! At Velocity Calibrations, we use the Scheibner CMS to not only measure your geometry, but also optimize your bike’s handling. Professional race teams have known this for years, and now we bring this same technology to you at an affordable price. The foundation of a well handling bike is motorcycle geometry.
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