This weekend, the Wenyu River Park in Beijing was the place to feel the thrill of speed. With batteries installed, switches flipped, and cars placed on the track, the sensors of an automatic timer detected the first burst of power from the motors. In the blink of an eye, a small miniature four-wheel-drive car raced away from the grey track.
Located at the junction of Chaoyang, Shunyi, and Changping districts, just off the Jingcheng Expressway outside Beijing's northeast Fifth Ring Road, the park hosted the Bambu Lab × Wenyu River "Back to Youth" Cup Mini 4WD Summer Sprint from July 18th to 19th. The event featured multiple segments including team assembly races, speed races, and championship battles. The competition format was upgraded with the introduction of a new, 130-meter-long track.
For many born in the 80s and 90s, miniature 4WD cars were a childhood passion. At the event, numerous participants brought their foldable toolboxes. Opening the lids revealed layers neatly organized with car parts, batteries, motors, screwdrivers, cutters, and glue. One competitor explained, "Unlike sports like basketball, 4WD racing is quite pure—you just put your car on the track and let it run."
The park's popular miniature 4WD track originated from a designer's playful idea. In late 2021, landscape designer Wang Weiqi, while working on the park's design, was inspired by water channels. He conceived the idea of making a landscape feature that could also serve as a racetrack. He researched standard 4WD track specifications, meticulously refining the clear width, slopes, and curve designs, and cleverly integrated auspicious cloud patterns into the track layout.
This design, which included a touch of personal passion, was approved and constructed in 2022. In 2025, Wang shared his original design concept on social media, bringing public attention to the track. It quickly became a cherished spot for enthusiasts. The park management preserved and upgraded the track and, responding to public interest, transformed online suggestions into an official competition.
Technology has also been integrated into this nostalgia-filled competition. As the title partner, consumer 3D printing company Bambu Lab provided technical support, using 3D printing to produce participant gifts, trophies, and some track accessories.
One of the event referees, Liao Bing, known as "Uncle Bao," demonstrated his self-made automatic starter and timing system. The core hardware is encased in a 3D-printed shell. Liao explained that during his first visit to watch a race at the park, he noticed the starter waved a flag, competitors manually released their cars, and timers recorded results with stopwatches. This process meant timers worked for hours under high intensity, and manual timing and starting inevitably introduced errors.
As a retired engineer, Liao applied his expertise in mechanics, electronics, programming, and systems engineering to design this millisecond-precision timing device, automating the entire start-to-finish process. 3D printing allowed for a custom shell that precisely fits all components, an achievement difficult with traditional wood or generic plastic casings.
It is understood that Beijing Wenyu River Park has designated the "Back to Youth" Cup Mini 4WD Race as a year-round series for 2026. The park plans to host multiple themed events, continuously enriching the experience and gameplay to establish a unique miniature 4WD culture hub in Beijing.
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