Folding bicycle

A folding bicycle or folder is a type of bicycle that incorporates a number of hinges or joints, which may be lockable, that permit it to be folded into a more compact size, typically via folding one or more of the bicycle's components, most often the frame.

Folding bicycles are popular in East Asia and the United Kingdom, but are less common in the United States. Their major advantage is that they can be folded up and taken on public transport and into buildings where conventional bicycles cannot be taken. This has advantages to commuters as the bicyclist does not have to chain the bicycle in the street and allows journeys using public transport to be completed in part by bicycle. Folding also makes transporting a bicycle in an automobile easier.

As an alternative to folding some bicycle makes achieve the same result by being able to be separated into two parts for easy storage and packing. As there are fewer such bicycle makes they are usually grouped in the same category as folding bicycles.

Performance

One possible explanation for folding bicycles' lack of popularity compared to conventional bikes is the perception of compromised fit and performance.

On the street folding bikes are capable of high performance. The idea that a folder is slower than a conventional bike doesn't necessarily hold true.

A Moulton bike (whose frame separates in two) was used to win a criterium race on the streets of Toronto, Canada where acceleration and maneuverability gave it an edge over conventional bikes. A Moulton was also used to set a human-powered vehicle speed record on an indoor track, behind a pace vehicle. An Airnimal folder was ridden to a 3rd place victory at the world time trial championships.

According to the Bike Friday FAQ, here: http://www.bikefriday.com/LexiconFull.cfm?ID=53

"...tests have shown that up to 16 mp/h, the small wheel is more efficient than a big wheel. Between 16 and 33 mp/h there is little difference. Over 33 mp/h the gyroscopic effect of the big wheel makes it more effective. Most folks do not go over 33 mp/h..." (Note: the Tour de France averages somewhere around 25mp/h and those are world class athletes including the likes of Lance Armstrong.)

In order to make a folding bicycle as compact as possible certain trade offs are often made:

Folding bicycles often use small diameter wheels. All else being equal large diameter wheels give a smoother less bumpy ride than the smaller diameter wheels. Shock absorbers can be incorporated into the design of a bicycle to give a smoother ride. The shock absorber will absorb some of the energy that would otherwise be used to move the bicycle forward in a more rigid bicycle.

Folding bicycles often have a shorter wheel base which results in a rougher ride.

Folding bicycles often break or fold in the middle of the frame, which depending on the design, can weaken the frame and cause more energy absorbing flexing.

Folding bicycles often have seat posts and steerer tubes which are elongated causing larger bending stresses where the tubes meet the frame.

Folding bicycles universally have many more parts, to allow folding and lock the frame when unfolded. This results in a much more complicated design, with more parts that can fail.

Size

Folding bikes generally come with a wider range of adjustments than conventional bikes for accommodating different riders.

Seatposts and handlebar stems on folders extend as much as four times higher than conventional bikes. For even greater range of adjustment, longer aftermarket posts and stems are available.

While folders may appear to be "small," the distance between center of bottom bracket, top of saddle and handlebars is often identical to that of conventional bikes, the primary factors in determining if a bike "fits" a rider.

You can see this concept illustrated by this diagram—a 20" wheeled KHS F20 folding bike overlaid on a conventional, 700c wheel (27"), non-folding KHS Flite 100.

The rider's seat, hands and feet are in exactly the same position for either type of bike.

Price

Folding bicycles cost more than non folding bicycles with the same performance related features.

Challenging perceptions

While it's important to shop carefully for a bicycle—including a folder—with an adjustment range to suit the rider and with a suitable drivetrain and tires capable of low-friction and high speed, it's hoped continued education of the consumer will help to popularize the folder by dispelling the myths of "too small, too slow".

The wide variety of folding bicycles reflects the different methods to allow a bicycle to fold. For example, bicycles such as the Bazooka simply fold in half. Bikes such as the Birdy and Brompton fold in a more complicated manner but fold smaller. Bikes such as those from Airnimal and Bike Friday partly fold and partly disassemble. The Giatex folds and retracts, adjusting to the size of the rider. The iXi literally breaks into 2 halves. The Strida's triangular frame folds to resemble a unicycle. Regardless of how each folds, the result is easier to transport and store than traditional bicycles.

Wikipedia pages refering to folding bicycles

Category:Folding bicycles
Alex Moulton Bicycles
Birdy
Bike Friday (Green Gear Cycling, Inc)
Brompton Bicycle
Montague Bicycles
A-bike (from Clive Sinclair, of C5 fame..)

External Folding Bike Links

A to B magazine – The place for those interested in folding bikes.
The Folding Bike Forum on BikeForums.net
Cheg's 'Super-Modified' Raleigh Twenty folder - proof a folder made in the 1960s can still compete with its modern counterparts.
Chicagoland folding bike society
Folding Bicycle Information compiled by Steven M. Scharf (nordicgroup.us)
Folding bike forum at dahon.com
The Folding Society – guides to choosing a folder and reviews of many types
LittlePixel's Raleigh Twenty site with a directory of other converted bikes.

Directory of Folding Bike manufacturers

External web sites offering links to manufacturers of folding bikes:

a huge, growing list of folding bike manufacturers - by folding-fan 'Chop', with countries and regions indicated. Chop owns many folders and writes comparisons between them on other parts of his site.

References

Hadland, Tony. It's in the Bag! – a History in Outline of Portable Cycles in the UK. ISBN 0950743186

Cycle types

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