martes, 12 de agosto de 2008

Preguntas frecuentes de Brompton en inglés

Preguntas frecuentes acerca de las Brompton extraidas de la Web Oficial de Brompton.

Archivo original: Brompton Technical FAQs


Below you will find answers to some of the questions we hear most often. We will continue to add to the topics covered, but if you have a question that isn't yet addressed, you can post a question here.

What is the maximum load a Brompton can carry?

We stipulate that the bike is designed to carry a maximum load of 110kgs plus 20kgs of luggage; that is the equivalent to 242 lbs plus 44 lbs.

What is the maximum height a rider can be?

The maximum height of a rider is dictated by their inside leg measurement; the standard seat pillar is adequate for those with an inside leg measurement of 32 inches, or 33 inches with a rail saddle, the extended seat pillar is 60mm (just under 2.5 inches) longer than the standard. The telescopic seat pillar is designed for those with an inside leg greater than 35 inches or for taller riders wishing to minimise how far the seat pillar protrudes from the folded package. The telescopic seat pillar gives up to 175mm (nearly 7 inches) of extra height yet projects only 20mm (just under an inch) from the folded bike. For more information on this please see the Bike Explorer section of our website.

Do you produce a hard case for travelling with your Brompton by plane? If not, why not?

We do not produce a hard case. We would not recommend stowing a Brompton in a hard suitcase as this can potentially damage the bicycle if it is not suitably cushioned; the hard case can also encourage less than careful treatment of the item.

We produce the Brompton bag (B bag) for transporting the bike on such occasions. The B bag is a soft bag made of tough Cordura, it has a shoulder strap, handles and a steel plate in the bottom with castors so that the bag and bike can be rolled around. We regularly transport bikes around the world in B bags, without issue. For more information on this please see the Accessory Explorer section of our website.

Do you have a factory show room from which your bikes can be purchased?

We do not have a factory show room. We do not sell directly to consumers; it is only possible to buy our bikes from our one of our dealers, please see the Dealer Locator section of our website to find your most convenient Brompton Dealer.

Aren't small wheels inefficient and more dangerous than large wheels?

We put 16" wheels on our bikes primarily for the obvious reason - they allow a compact folded package. However, smaller wheels bring other advantages: they offer superior acceleration and lose less speed to wind resistance and, when fitted with high pressure tyres (as Bromptons are), the actual rolling resistance is similar to that of large wheels; the unpaced (i.e. unassisted) cycling world speed record was set using a small-wheeled Moulton AM7 (51.29 mph over 200m in 1986).

Smaller wheels are also lighter and stronger than larger, longer-spoked wheels, but many people worry about their capacity to handle potholes and other unforgiving terrain. Despite appearances, our wheels fare pretty well on pitted streets and, because of their greater manoeuvrability, it’s easier to avoid the obstacles in the first place. The only times you have to take more care with small wheels is on a gritty surface or when riding obliquely across a groove or step in the wet, circumstances which require care on any bicycle in any event.

Why do your bikes have a steel frame?

Steel is actually coming back into favour with many quality bicycle manufacturers; for all the perceived advantages of other materials, steel continues to offer an often-unbeatable combination of rigidity, strength, versatility and longevity.

Carbon fibre and other composite materials have a role to play in creating top-end racing bikes, but such materials lack the robustness to withstand the rigours of Brompton daily use. While cutting the weight of our bikes down is important to us, it can not come at the expense of durability.

Many manufacturers use aluminium in their frames but we currently do not. While it is lighter than steel, aluminium is also much less stiff and the frame of an aluminium Brompton would have to be considerably thicker than our current steel frame - the weight saving at present would be marginal and the folded package bigger than our current configuration.

Why aren't there more gears on your bikes? Why do you use hub gears?

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.

Why do you not use V brakes or disc brakes on your bikes?

The specially-designed dual-pivot brakes on a Brompton are simpler to maintain than other styles of brake, and their cabling is easier to incorporate into our compact design. The design has been refined over several years and gives good braking performance: these callipers allow modulated braking through to full locking of the rear wheel.

At Brompton, innovations are never adopted just for the sake of novelty or marketing spin - they must offer superior performance. Although conventional V-brakes or disc brakes certainly offer advantages on some bikes, they would add little to the Brompton; moreover, they would compromise the small size of the folded package and, in the case of disc brakes, would add unwelcome weight.

Why can't the height of the handlebars be adjusted?

There are a number of reasons why we have resisted adding this functionality: besides adding weight to the bike, it would cause problems for the routing of cables, particularly during folding, and would therefore impair the functionality of brakes and gears. Moreover, the height is fine for most users, including a number of very tall Brompton employees, especially since we introduced different handlebar styles in the summer of 2005.

However, we are considering developing an extended handlebar stem as part of our programme of product development.

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