Over the last twenty years, there has been a trend towards putting ever more gears on bikes; in part this reflects the rising popularity of mountain-biking, but it's a movement that owes at least as much to marketing as to genuine functionality. After all, how many of those gears actually get used?
By focusing solely on the number of gears on a bicycle the vital considerations of gear range and efficiency are overlooked. Often, the effective range of the gearing systems (smallest and greatest distance travelled for one rotation of the pedals in the lowest and highest gears) has not increased - extra gears have simply been squeezed in without adding much to the range at the top or bottom of the gearing. We set out the gear range and ratio for all our gearing options, in our Data section
Multi-geared derailleur systems rarely give satisfactory gearing on a small-wheeled bike; on a folding bike they are also vulnerable to damage, difficult to keep in adjustment and cumbersome. To achieve the wide range of gears they offer, derailleurs typically force the chain to manage acute angles between the chain wheel and rear sprockets; our own simpler derailleur system, used on our 2-speed and 6-speed bikes, is designed to keep the chain running straight regardless of the gear selected, and adjustment is seldom needed.
Hub gears are generally a superior solution for a folding bike: the gears are protected inside the hub housing, making them easy to maintain and avoiding the problems caused to derailleur systems by dirt, rain and the odd knock. Our gearing options mainly revolve around the reliable, compact and efficient 3-speed hubs perfected over many decades by Sturmey Archer and SRAM. Other hub gears on the market offer more gears but do so at the expense of efficiency; without getting too technical, the three gears in our hubs are achieved through one set of planetary pinions [rotors], whereas, for example, the leading 8-speed hub on the market channels the cyclist's energy through three sets of pinions, inevitably resulting in greater energy loss.
One final thought: the Tour de France riders climbing Alpe d'Huez this summer will not be using 27 gears to conquer the most fearsome climb in the cycling calendar; you probably won't need that many gears either.