In its time, the Cyclo Sport was a, slightly belated, attempt to produce a 'modern', racing, pull-chain, twin pulley derailleur. Simplex had made a runaway success of its 1948 Simplex Tour de France, which had two sprung pivots, which made it easy to remove the wheel, but a fairly insane design of pulley cage, which gave limited capacity and a rather large chain gap. Huret had responded in 1950 with its Huret Competition, which had only one sprung pivot, which made it harder to remove the wheel, but offered a more rational and offset pulley cage, giving greater gear capacity and a smaller chain gap. So for 1951 Cyclo tried to offer the best of all worlds. The Cyclo Sport had a rigid B-pivot, but you could loosen it to remove the rear wheel, almost matching the convenience of the Simplex. It also had a sensible and offset pulley cage, giving the advantages of the Huret.
In Britain, the Cyclo design was manufactured in the UK by the Cyclo Gear Company, and it triumphed in the market. In France, however, the Cyclo gear was better made and therefore more expensive in what was a very price competitive market. Cyclo was also used to being a successful up-market, quality, leader in the touring market and assumed that the same approach would simply work in the racing world. Perhaps because of this, it never really grasped the importance of getting down and dirty in the messy world of sponsoring professional cyclists and their teams. Unlike Simplex and Huret, Cyclo derailleurs were never ridden to victory in the Tour de France. In terms of commercial success the Cyclo Sport was always an also-ran.
Written on the inner pulley cage plate of this example is '4V-Chaine 2,38', indicating that it is a 4 speed, 3/32" chain, version.
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