bars pedals and saddle are in the same position as a normal bicycle industry manufacturing founded 3 june 1976 1 headquarters brentford greater london england uk key people andrew ritchie founder and technical director will butler adams managing director 2 products folding bicycle revenue 10 million 3 4 operating income 750 000 4 number of employees 115 5 3 website www.brompton.co.uk brompton bicycle is a manufacturer of folding bicycles based in brentford london . the brompton folding bicycle and accessories are the company s core product noted for its self supporting compact size when stored . all available models of the folding bicycle are based on the same hinged bicycle frame and 16 inch 37 349 mm bicycle wheel tyre size . components are added removed or replaced by titanium parts to form the many variations . the modular design has remained fundamentally unchanged since the original patent was filed by andrew ritchie in 1979 6 with small details being refined by continual improvement . ritchie was awarded the 2009 prince philip designers prize for work on the bicycle . 7 8 9 in reviews of folding bicycles the brompton is often the winner . 10 11 12 13 brompton is the largest volume bicycle manufacturer in britain 14 producing approximately 40 000 bicycles each year . 5 the company also operates a bicycle hire system . 15 contents 1 design 1.1 the fold 1.2 models 1.2.1 factory additions 1.2.2 accessories 1.3 history 1.4 customisation 1.4.1 replacements 2 company 2.1 clones and licensing 2.1.1 court cases 3 see also 4 references 5 external links design edit folded brompton on a public bus four stages in folding . the final step of lowering the saddle locks the package together all brompton folding bicycle models share the same curved frame consisting of a hinged main tube pivoting rear triangle fork and hinged handle bar stem . the main tube and stem are made of steel in all models . the rear triangle and fork are either steel or titanium depending on model . the steel sections are joined by brazing not welding . wheels are 349 mm 13.7 in rim size carrying tyres with 16 tread diameter . the handlebars and some peripheral components are aluminium . a brompton bicycle uses over 1 200 individual pieces 80 % of which are manufactured solely for the brompton design . citation needed as of 2010 update the combinations allow one two three or six speed gearing options to be factory fitted with higher or lower gearing available as an option . the brompton uses a combined rear fold and suspension design . during riding the rear triangle rests on a rubber spring to provide suspension between the rear wheel and the main frame supporting the rider . the suspension block is kept in compression by the rider s weight . a factory fitted firm suspension block is offered as an alternative to the standard block for heavier riders or those wanting a more responsive ride . there is no suspension for the front wheel although the titanium forks of the superlight versions provide a small amount of spring . the fold edit the elements which allow the fold to work are a pivoting rear triangle allowing the length to be shortened while keeping the bicycle chain in the same alignment . there is a slight arch in the main frame to allow the wheel to swing under to the parked position ; a chain tensioner arm capable of swinging through a wide arc in order to control the full length of the chain during folding without the chain coming loose . in the folded position the chain is looped back on itself ; small wheels on top of the rear mud guard and or carrier to allow the folded bike to be rolled ; a main frame hinge in the centre of the bicycle allows the front wheel to be swung around and placed against the rear wheel . as the front wheel also rotates freely for steering purposes the front wheel remains pointing forwards even when folded ; a handlebar stem with the hinge placed at 45 degrees to the rest of the bicycle allowing handlebars to swing through 180 degrees and lie parallel with the wheels when folded ; a seat post combining variable height adjustment and locking . when lowered during folding the base of the post locks against the lower stop disc preventing the folded package from swinging open ; a folding pedal on the left hand side . the final folded package is 565 545 250 mm 22.2 21.5 9.8 in provided the standard seatpost is used and weighs between 9 12.5 kg 20 28 lb depending on the configuration . the standard saddle of 2009 and later models acts as a carrying handle for the folded bike with finger grip ridges on the underside . with practice folding and unfolding takes between 10 20 seconds making the brompton popular with commuters . models edit models are signified with a letter each side of a number to describe the handle bar type number of gears and factory attached fixtures respectively . a suffix is appended to show the inclusion of titanium upgrades . as an example the model code of m3r refers to classic m handle bars 3 gear speeds using an internal hub and an r for having a rear rack . the same model making use of titanium for some parts would be m3r x . handlebar style gearing choice fixtures f 1 material s sporty 1 single speed e minimal ; no mudguards no pump x optional lighter titanium forks triangle and sundries m traditional f 1 2 two speed derailleur l mudguards p dual height 3 three speed internal hub r mudguards and rear rack h upright 6 internal hub and derailleur a b until 2007 all brompton bicycles had m style handle bars with the fixtures being c no mudguards l mudguards or t rear rack and dynamo lighting . these roughly map to the present e l and r models . only 3 or 5 later 6 gears were offered and this was written after the type . a late 1990s t5 would be similar to a present m6r while a c3 would be close to the present m3e . the old marketing terms were companion lightweight and touring . factory additions edit different colour folded brompton bicycles in new york . half retain their supplied stock saddle all models may have the wheels on the corners of the rack replaced with larger eazy wheels to aid pushing when folded and to give greater heel clearance than the stock rollers . all models can choose to have no lights lighting powered from battery or two variants of front wheel hub dynamo . seat posts can be swapped between standard length extended or telescopic for tall riders titanium and later aluminium equivalents previously fitted to the lightweight models are no longer available . bicycles are offered in four colours at no additional charge black white orange and cobalt blue . 16 other colours raw lacquer and titanium are available at extra cost . titanium areas are left unpainted in their natural titanium colour . the standard brompton saddle can be substituted by a brooks b17 special leather saddle ladies or men s versions . non titanium models have braze on fittings for holding the supplied zefal hp compact high pressure bicycle pump . all models may have the front luggage block fitted to carry cargo this is fitted to the main frame rather than to the forks or handle bars to avoid interference with the steering . hub dynamo options use a special narrow width son xs hub dynamo fitted at the centre of the front wheel and manufactured by schmidt maschinenbau or a less expensive hub dynamo manufactured by shimano . until 2009 bottle shaped tyre dynamos were used for standard permanent lighting . new bicycles have a choice between brompton specific shimano or son xs hub dynamos . a full superlight variant uses titanium to save weight combined with lighter wheel components . the option replaces the rear triangle and front forks with titanium and other smaller parts with titanium or aluminium . the main frame structure remains steel . this upgrade represents the largest cost increase of any upgrade and reduces some variants to below ten kilograms in weight . the titanium rear triangle has no provision for mounting a pump and a pump is not supplied with titanium models saving approximately 75 grams 2.6 oz . tyres can be swapped at any point between kevlar based brompton branded tyres lighter faster schwalbe kojak or more robust and puncture resistant schwalbe marathon . whilst no longer factory fitted brompton bicycles originally used raleigh record tyres and continued to do so on the lower end model until the 2000s . citation needed aftermarket tyres include the schwalbe marathon plus a heavy but very puncture resistant model . accessories edit classic m handlebar and rear rack vs s handlebar and no rack p handlebar detail of the folding pedal a small saddle bag can be fitted behind the saddle for the brompton cover and any tools or spares . most of the handlebar types can also accommodate standard handlebar bags . when fitted with a front luggage block brompton offers a choice of folding basket large touring pannier the t bag two variants of bicycle messenger style flip over bag the s or the larger c bag a waterproof option available in two colors manufactured by ortlieb the cotton duck canvas bike bureau known as the city folder from carradice or a leather attach case the a bag can be attached to the bicycle . these bags internally share a common design of luggage frame which can also be used separately . in the case of the carradice bag this frame must be purchased separately from some retailers . history edit design changes have generally been introduced so they can be retrofitted on earlier models . rear rack redesigned in the 1990s using cast aluminium five speed hubs until discontinuation after the closure of sturmey archer in 2000 handlebar stem hinge switched to a jig brazed system sram hub rear triangle changes to suit sram hub after the closure of sturmey archer derailleur allowing 6 speed 2 3 evenly spaced gears main tube hinge in 2003 the introduction of a new machined hinge on main tube increased the wheel base by 30 millimetres 17 handle bar clip reinforced wire clip providing increasing gripping to secure the handle bar stem when folded down . handlebars two alternative handlebar designs ; the original handlebar being redesignated as the m type . titanium parts saving approximately 1 kilogram combined 18 dual action calliper brakes later fitted as standard to both the front and back wheels rear triangle clip allowing the rear triangle to be clamped to prevent automatic folding when the bicycle is lifted whilst unfolded . for example when being carried up steps . wide range hub brompton wide range bwr hub with a wider gear ratio spacing more suited to the brompton s smaller wheel size since 2008 19 non folding pedal new right hand non folding pedal designed to increase robustness and balance the folding pedal . notch added to prevent over folding of left hand folding pedal upright handlebar since 2012 handlebar style h customisation edit further modifications are provided by some brompton dealers or skilled individuals the most prominent examples being rear hub alternative hubs all tend to be wider than the narrow brompton rear triangle allow citation needed necessitating extensive stretching and modification work shimano nexus seven eight or eleven speed hubs . fourteen speed rohloff speedhub . sturmey archer xrf8 eight speed hubs . vintage sturmey archer medium or close ratio internals which can be screwed straight into the oem hub shell citation needed rear axle derailleur gears either