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File:Andrew ritchie brompton.jpg

Designer Andrew Ritchie holding his folded Brompton Bicycle


Four stages in folding. The final step of lowering the saddle locks the package together

Brompton Bicycle is a bicycle manufacturer based in Kew Bridge, London, in the United Kingdom. It is notable for its folding bicycle and being the last transport manufacturer of any kind based in the capital city. It is the largest volume bicycle manufacturer in Britain,[1] the other being Pashley Cycles. Approximately 22,000 bicycles are produced by the company each year[2][3] of which 70 percent are exported.[2] The company was awarded the The Queen's Award for Export in 1995.[4]

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 (349 mm) wheel size. Components are added, removed, or replaced by titanium parts to form the variations. The modular design has remained fundamentally unchanged since the original patent was filed by Andrew Ritchie in 1979,[5] with small details being refined by continual improvement. Ritchie was awarded the 2009 Prince Philip Designers Prize for work on the bicycle.[6][7] In reviews of folding bicycles, the Brompton is often the winner.[8][9][10]

Folding bicycle[]

All Brompton folding bicycle models share the same curved frame, consisting of a hinged main tube, pivoting rear triangle, and hinged handle-bar stem. The steel sections use brazing to join the steel (instead of welding). Wheels are 349 mm rim size, carrying tyres with 16" tread diameter. The handlebars and some periphery components are aluminium.

A Brompton bicycle uses over 1,200 individual pieces, eighty-percent of which are manufactured purely for the Brompton design.

Template:As of the current combinations allow one-, two-, three-, or six-speed gearing options to be fitted at the factory, with an optional further factory-fitted gear reduction of around twelve percent.
The Brompton uses a combined rear fold and suspension design. During riding, the rear triangle rests loosely 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. All Bromptons now feature a latch allowing the rider to chose between automatic parking, or keeping the bicycle rigid whilst being carried unfolded. There is no suspension for the front wheel, although the use of Titanium forks provides a small amount of spring.

The fold[]

The "Brompton fold" is unique to Ritchie's design, allowing the bicycle to shrink both vertically and lengthwise during folding, but keeping all of the parts attached to one another. The elements which allow the design to work are:

  • Pivoting rear triangle, allowing the length to be shortened, whilst keeping the bicycle chain in the same alignment, there is a slight curve in the main frame to allow the wheel to swing under.
  • Chain tensioner arm capable of swinging through a wide arc, in order to absorb the full length of the chain during folding without the chain coming loose. The chain ends up looped back on itself.
  • Angled handle-bar stem, on a bicycle the handle bars are at right-angles to the rest of the bicycle. Having the hinge placed at 45-degrees to the rest of the bicycle means that the handle-bars swing through ninety degrees and lay parallel with the wheels when folded
  • Main frame hinge, the fold 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.
  • Seat post combining the function of 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

The final folded package is 565×545×250 millimetres (22.2×21.5×9.8 in) and weighs between 9–12.5 kg (20–28 lb) depending on the configuration. Folding takes 10–20 seconds meaning that normally the bicycle can be pushed or cycled until the very last minute and only folded before stepping onto the train or entering a building.


Models are named using a code containing two letters either side of a number to describe the handle bar type, number of gears and factory attached fixtures. An optional 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, but making use of titanium where possible would be "M3R-X". Template:Clear

Handlebar style Gearing choice Fixtures[f 1] Superlight upgrade
S sporty 1 single speed E minimal; no mudguards, no pump -X optional lighter titanium forks, triangle and sundries
2 two speed derailleur
M traditional[f 1] L mudguards
3 three speed internal hub
P dual height R rear rack
6 internal hub and derailleur
  1. 1.0 1.1 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[]


Different colour folded Brompton Bicycles in New York. Half retain their supplied stock saddle.

"R" models may have the wheels on the corners of the rack replaced with larger eazy wheels, to aid pushing when folded. All models can choose to have no lights, lighting powered from battery, bottle shaped tyre dynamo or front wheel hub dynamo. Seat posts can be swapped between standard length, extended or telescopic for tall riders (each with a titanium equivalent). Bicycles are offered in black or red matt colours as standard, with the optional selection of further colours, or transparent raw lacquer coating. 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. The hub dynamo option uses a special narrow-width SON XS hub dynamo fitted at the centre the front-wheel and manufactured by Schmidt Maschinenbau.

A full superlight variant uses titanium to save weight, combined with lighter wheel components. The option replaces the rear triangle, front forks, seat post and other smaller parts. 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.

Tyres can be swapped at any point between Brompton yellow, kevlar based Brompton green, heavier Schwalbe Marathon or very narrow Schwalbe Stelvio.[t 1]

  1. 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.


A small saddle bag can be fitted behind the saddle for the Brompton cover and any tools or spares.

When fitted with a front luggage block, a choice of folding basket, large touring pannier or two variants of bicycle-messenger style flip-over bag can be attached to the bicycle. These bags internally share a common design of lugguage frame, which can also be used separately.


The core design has proved to be very close to the optimum; the folded package being restricted roughly to the size of the wheels used, plus a small overhead. As such, design improvements have generally been subtle and introduced in such a manner as that they can be retrofitted on earlier production models of the bicycle.

File:2 red Bromptons 10Av 30 jeh.JPG

Classic handlebar and rear rack, vs T handlebar and no rack

Rear rack
Redesigned in the 1990s using cast aluminium
Five-speed hubs
until discontinuation after the close 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 close of Sturmey Archer
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 five centimeters.[citation needed]
Handle-bar clip
reinforced wire clip providing increasing gripping to secure the handle-bar stem when folded down.
Two alternative handlebar designs; the original handlebar redesignated as the 'M' type.
Titanium parts
saving approximately 1 kilogram combined
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
Non-folding pedal
new right-hand non-folding pedal designed to increase robustness and balance the folding pedal.


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 forks allow, necessitating extensive stretching and modification work
  • Shimano Nexus seven- or eight-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
Rear axle
Derailleur gears either in addition to, or instead of the standard internal hub gearing
Bottom bracket
  • Schlumpf Mountain Drive:[11] Fitting a Schlumpf Mountain Drive to the bottom bracket to give a selectable 250% reduction, thereby doubling the number of gears available to two-, four-, six-, or twelve-speeds
  • Additional front derailleur chain-rings as from on a mountain bike
  • Oversize, or elliptical ("egg") rings giving higher possible top-speeds for extremely fit riders
Front wheel hub
  • Electric motor, combined with a battery bank attached to either the rear rack, or stored in the front pannier
  • Pantour suspension hub
  • Dynamo hubs. Brompton now offer a narrow-width SON XS as a standard factory supplied upgrade
  • Custom-made luggage using the Brompton luggage frame
  • Rear luggage attached to the seat-post
Contact points
  • Leather or other handlebar grips; replacements need to be approximately 95-100mm wide compared to 130mm for other bicycles
  • Upgraded saddles - Brompton offer a branded Brooks B17, but any saddle can be fitted if the Brompton "Pentaclip" adapter is used


Brompton owners and designers with suitable engineering expertise regularly try to improve the design, although there is limited scope to do so as any additions attached are likely to compromise either the final folded size, carried weight or folding action.

  • SP. In the United Kingdom, builder Steve Parry specialises in producing a bicycle called the SP, based on Brompton components combined with a seven-speed derailleur, V-brakes, carbon fibre seat post and a suspension handlebar system.
  • "Brekki" recumbent upgrade kit. A collection of add-ons offered by a German bicycle to convert a basic Brompton in a recumbent bicycle design and the cost of a larger folded package and heavier weight.[12]
  • Ultimate Folding Bicycle. An on-going development involving wholesale replacement of virtually all original Brompton frame components with titanium or lightweight versions. The result is a sub 8-kilogram bicycle with a Brompton fold and luggage compatibility.[13]
  • "Nano Brompton" - an upgrade to convert a basic Brompton to an electric bike by adding a powerful electric front hub motor to the Brompton, the motor adds some 2 kg to the overall bikes weight. [14]
  • "Brompton E-Freedom" - an upgrade to convert a basic Brompton to an electric bike by adding a powerful electric front hub motor to the Brompton, with nano-technology batteries, the whole kit (incl motor, battery, controller & throttle adds only 3.2kg to the overall bikes weight. [15]



Being wheeled in a partially-folded configuration

  • Replacements for the 16 x 1 3/8" tires are less common than for wider tires.
  • Many parts are custom made, which may bring delays and extra costs for repairs from other than authorized dealers
  • The bike is not suited to long rides as most models have restricted gears.
  • Brompton manufacture the basic frame in one size only. Riders requiring a bottom bracket to saddle top height of more than 715mm/28" can buy an extended seatpost to give a maximum saddle height of 775mm/30.5" (slightly more is possible with a Pentaclip adapter). There is also an telescopic seatpost option which gives greater height still and does not compromise the size of the folded package, although it adds substantial weight.
  • The handlebar height is not adjustable at all, although adventurous owners could try swapping the stem, e.g. an "M" for an "S" type.


In 1976 Andrew Ritchie founded the company, named after the Brompton Oratory, a landmark visible from his bedroom workshop where the first prototypes were built. At the time he was working as a gardener. Ritchie obtained backing from friends and sought to license the design, but after five years began manufacturing the bicycle design himself. Production ground to a halt in 1982 after which Ritchie continued to explore possibilities for continued manufacturing whilst undertaking other jobs.

Finally in 1986, again with backing from friends and former customers, enough was raised to resume production on a larger scale. With a bank loan underwritten by Julian Vereker (founder of Naim Audio), production was restarted in a railway arch in Brentford. By early 1988, mass-production Brompton bicycles were once again in circulation.

In March 2009, Brompton Bicycle achieved a record monthly turnover of just under £1 million; the employees were rewarded with fish and chips.[16] In the same month, the company stated that it was hoping to continue a 25% rate of growth.[17]


In 1992, Brompton started an agreement with the Taiwanese-based company Neobike to allow the manufacture of a licensed copy for distribution in Eastern Asia; a market not already served by Brompton directly.[18][19] The licensing deal lasted approximately ten years until 2002. At this point in time, five senior Neobike employees had just been convicted and jailed for stealing trade secrets from Dahon and Ritchie stated that the contract was "under review".[20]

Originally Dahon had been working towards a licensing deal with Brompton Bicycle Limited, but the Dahon employees working on the deal left Dahon and started up Neobike instead with the agreement negotiated.[21]

Copyright infringment[]

Following the expiry of the Brompton patent, Neobike started to import its Scoop One and Astra Flex V3 models into Europe.[22] A court case was held at the Groningen civil court in the Netherlands on 24 May 2006, which ruled that the industrial design of the Brompton folding bicycle was protected by copyright. Additionally, the Neobike manual included direct copies of drawings found in the Brompton user manual.[23]

The Brompton Bicycle Limited v Rijwielbedrijf Vincent Van Ellen BV ruling held that there was creative flexibility in the design for a bicycle beyond those choices made purely for functional reasons; in the Brompton case this included the M-style handlebars, curved main frame tube and the cable-placement.[23] Each of these were noted to be distinctive design decisions that another manufacturer could change without compromising the ability to create a functional folding bicycle. Such a level of perceived similarity was therefore likely to cause "confusion in the market" under the Dutch copyright law, Article 13. Neobike did not choose to appeal and Brompton Bicycle was granted the right to have all of the imported bicycles destroyed and an injunction against future imports by Neobike.[23]


An unlicensed Chinese-made Brompton "clone", the Merc, is available for less than half the cost of a Brompton. It has an aluminium alloy main frame (rather than steel) but is no lighter in weight. Components also differ in quality, although the same 3-speed hub is used.

See also[]


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  16. Template:Cite web
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  18. Template:Cite web
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  20. Template:Cite web
  21. Template:Cite web
  22. Template:Cite web
  23. 23.0 23.1 23.2 Template:Cite web

External links[]

Template:Folding bicycles Template:Coord

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