Derny race: motor-paced cycle racing and the pacing machine

Design and operation

The machine known as a derny is a small motorised bicycle built specifically for pacing. It is typically ridden by a pacer who sits in an upright position to create a stable pocket of slipstream for the following cyclist. Dernys are designed to provide smooth, predictable acceleration and steady speeds so the cyclist can maintain a close distance directly behind the machine. Although the original manufacturers are no longer active, the name "derny" has become the common term for any pacing motorbike of this style.

History and origin

The original dernys were manufactured in the late 1930s by the Paris firm Roger Derny et Fils and were first used to pace riders in motor-paced competitions. The product and technique spread across Europe, particularly in track events and six-day races, where pacing improved spectacle and speeds. The firm itself has ceased operations, but the term endures and describes the class of motor pacing machines used in racing today. The practice also evolved into unique formats such as the derny-paced events in continental six-day meetings and certain keirin-style races.

Race formats, rules and common uses

Derny races vary by venue and tradition, but they share core elements: a pacer on the derny leads the cyclist or a group for most of the distance, and the rider positioned behind must stay within the pacer’s slipstream until a designated point when sprinting begins. Formats include individual paced time trials, mass-start derny races on the track, and motor-paced road events. Dernys are also used in training to help riders practice high-speed drafting and to simulate race conditions.

Characteristics, tactics and safety

• Drafting technique: The cyclist tucks in directly behind the derny to minimize wind drag and conserve energy.
• Pacer role: The pacer controls tempo, keeps a steady line, and often adjusts speed to set up a decisive sprint finish.
• Equipment differences: Dernys differ from larger pacing motorcycles used in stayer events; they are smaller and ridden more like motorised bicycles.
• Safety: Close proximity requires skill from both pacer and cyclist; officials enforce strict positioning to reduce risk.

Notable facts and distinctions

Derny pacing is distinct from other forms of motor-paced racing primarily by the size and handling of the pacing machine and by the close, sustained drafting it affords. Historically, ordinary motorbikes ridden by photographers or officials were sometimes used to help riders during races, but riding in front of competitors was later restricted or banned to preserve fair competition and safety. Modern derny events remain a niche but celebrated part of track cycling culture, showcased at six-day meetings and special track programmes in countries such as France and across Europe.

Whether as a competitive discipline or a controlled training tool, the derny continues to shape how cyclists experience very high-speed racing and how pacer–rider partnerships develop tactical nuance in the sport.