This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Some track cyclists appear to break the rules of physics, but a new study, published in the journal Royal Society Open Science, has created a model explaining the illusion. The results suggest that a quick succession of well-timed moves can help cyclists get a head start without actually breaking the rules of the race or the rules of physics.
Track cycling typically uses "standing starts," where events begin with the cyclists' rear wheels held in a starting gate. When the race starts, they are released and technically start from rest. Yet some elite cyclists have a nonzero forward bike velocity at the exact moment the signal occurs instead of a ramp-up from zero.
This apparent paradox is referred to as the "standing-start paradox." Earlier models of cycling starts often treated a rider's speed at the signal as a starting assumption but didn't fully explain the split-second transition between being held by the gate and sustained pedaling. While riders can't cross the start line before the official signal, they can move slightly in the offset region. The offset is the small space between the wheel and start line, which is set by the position of the starting gate and bicycle frame geometry.
According to the authors of the new study, smaller riders generally use smaller frames, which typically put the front wheel farther behind the start line and increase the offset. Larger frames tend to reduce that offset. The researchers say that a nonzero initial velocity may be imposed during a "short explosive transitional regime" that precedes steady pedaling, thereby explaining the paradox.
The team studied the paradoxical starts by using high-speed video to track bike movement of three elite French track cyclists and reconstructing each rider's center of mass. They measured the starting gate's braking force and riders' pedal torque, then combined these measurements into a physics model. Predictions from the model were then compared with real start-speed traces.
They found that the apparent paradox is explained by a brief whole-body backward-then-forward movement before and during gate release, which transfers momentum to the bicycle. Riders shift their body mass backward, then rapidly forward, and slowing that forward body motion creates a powerful forward push on the bike. The results showed that this body-driven impulse dominates the first roughly 0.2 seconds, right before pedaling becomes the main source of acceleration.
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