[ 2-Wheeler Index ] [ Up one level ] [ 2. Evidence ] [ 3. Recommendation ] [ 4. New concepts ] [ 5. Other Theories ] [ 6. Links ] [ SiteMap ]

 1.3 Three steps when going into a turn:

According to the Torso-Arms-Handlebar theory, going into a turn can be broken down into three main steps as illustrated here:

Step 1: If the rider’s torso suddenly leans to its right, for instance, the 2-Wheeler leans to the left in reaction. So the front wheel is unconsciously oriented to the left by the Torso-Arms-Handlebar mechanism. The front wheel orientation generates a centrifugal force, or the tire-ground contact patch rapidly moves to the left, so that the 2-Wheeler is pushed to its right.

- The rider pushing-pulling on the handlebar when applying the Countersteering technique.
- The gyroscopic reactions of the front wheel caused by the 2-Wheeler leaning to the left.
- The front wheel 'Trail' acting as a lever around the front fork axis when the 2-Wheeler leans to the left.
- The front wheel leaned to the left and inducing a 'Camber Steer' effect to the left, even when still oriented straight ahead.

But as explained further down in this site, all these effects are negligible at slow speeds and thus cannot explain how a 2-Wheeler steers so easily at slow 'parking lot' speeds. On the other hand, they do become more important at higher speeds.

Step 2: The 2-Wheeler rapidly leans to its right due to the centrifugal force or the tire-ground contact patch’s left side movement.

When the 2-Wheeler’s lean angle is the same as the rider’s torso, the front wheel is oriented straight ahead. So there is no centrifugal force or tire-ground contact patch side movement generated to hold up the 2-Wheeler, which keeps on falling.

Step 3: The 2-Wheeler keeps on falling to the right, but the torso lean angle stays the same because the rider does not want to fall further. So the 2-Wheeler keeps on falling to the right further than the rider’s torso, which orients the front wheel towards the right through the Torso-Arms-Handlebar mechanism. Finally, this front wheel orientation lets the 2-Wheeler turn to the right and generates a centrifugal force that holds up the leaning rider and 2-Wheeler.

Note that at high speeds, the gyroscopic counter-reactions are strong and may flex the arms and elbows. So the rider may feel that he pulls or pushes on the handlebar according to the Countersteering technique. At such speeds, the Countersteering technique and the Torso-Arms-Handlebar theory are quite similar. But the Torso-Arms-Handlebar theory adds and explains that it is the torso lean angle that unconsciously starts and 'cleverly' controls the push-pull actions on the handlebar, through all the chain of events when going into a turn.

[ Next page ]

[ 2-Wheeler Index ] [ Up one level ] [ 1.1 TAH Mechanism ] [ 1.2 Slow speed stability ] [ 1.3 Three steps ] [ 1.4 Scientific principles ]