Start by holding the tape measure straight down from the front axle to the floor. Put a mark on the floor at that point. Then, place the tape parallel to the steering axle, following the angle of the steering head all the way down to the floor. Put a mark here too. Now all you have to do is to measure the distance between the two marks and you have your trail figure. It should read between 2 and 4 inches.
* Note: If your bike is equipped with rear suspension, have someone sit on the seat when you make these measurements, to simulate your actual riding conditions.
| Too Little Trail With too little and extreme cases negative trail, (steering axle mark behind the front axle mark), the bike will handle with unbelievable ease at low speeds, but be completely out of balance at high speed. It will easily develop a fatal high-speed wobble. Extremely dangerous! |
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Normal Trail Somewhere between 2 to 4 inches the bike will handle easily at both high and low speeds. Flowing smoothly through curves without swaying or wobbling. If you use a very fat rear tire, you should keep the trail as close to 4 inches as possible. A slightly large trail is also practical for touring. |
| Too Much Trail If the trail is more than 4 inches the bike will handle sluggishly at high speeds. It will seem almost too steady. You will have trouble balancing your bike at lower speeds, or on winding roads. It will feel generally sluggish and clumsy. |
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