A Brief History of the Derny

The stories and escapades of the Bordeaux-Paris are inextricably linked with the Derny, the name given to the small mopeds used to pace the riders in the second half of the event. The event had always featured some kind of pacing but up until 1931 this took the form of human power, pacing riders either riding individually or on tandems, triplets or even quads. In 1931 motorbikes were used for the first time and in 1938 the famous Derny was used for the first time. Dernys are well known to anyone who rides the track or who has watched the keirin event at any track meetings and all these bikes still in service to the current day trace their lineage back to a design by Roger Derny and Sons of Paris.

The Derny was designed specifically for pacing riders and includes several features not found on a normal moped. The special design of the gearbox, clutch and flywheel is such that the Derny pulls well at low revs allowing speed to be precisely controlled using the throttle and pedals. This ability is crucial when pacing a rider; we all know from experience that a difference of half a kph can be the difference between hanging onto the wheel in front and sliding silently backwards into the wind and out of the bunch.

The geometry and design of the Derny closely resembles that of the bicycle, giving similar handling properties to a bicycle, another key factor when pacing a rider. The exhaust also exits close to the ground to avoid the rider breathing in the fumes. Post-war, the company expanded its product range introducing new models designed less as pacing bikes (a limited market, after all) and more as practical machines for the French to go on holiday or get around town. Roger Derny & Sons sadly closed in 1958, having produced around 7000 machines. The organisers of Bordeaux – Paris continued to use their existing Derny fleet of until 1974, after which replica Dernys were sourced from Burdin.

Fascinatingly, during the days of the Derny-paced Bordeaux-Paris races, strict rules were enforced governing the attire of the pacer. No bulky clothing that might give greater shelter and therefore an unfair advantage, was permitted. Indeed, pacers were closely observed during the race to make sure they didn’t sit unduly upright and impart more shelter to their charges. Pacers were obliged to wear very similar clothing to their rider; the dress code stipulating:

1. A woollen, long-sleeved under vest.
2. A long-sleeved race jersey. If this has pockets, front or rear, they must be stitched up and made unusable
3. A pair of shorts as used by riders.
4. A pair of cycling shoes without tongues.
5. A pair of black or white socks as used by riders.
6. A pair of cycling or town gloves.
7. A sprinter-type crash hat.