Small-wheel bicycle


A small-wheel bicycle, sometimes called a mini velo or mini-velo, is an adult bicycle with a reasonable sized frame and relatively small wheels, usually of ETRTO 406 mm or less nominal diameter, which is smaller than the common 622 mm road bicycle wheel size or 622 mm, 584 mm or 559 mm gravel and mountain bike wheel sizes common on most full-sized adult bikes.
They can be folding or non-folding. While many folding bicycles are small-wheel bicycles, not all small-wheel bicycles can fold. Some small-wheel bicycles neither fold nor separate, such as the Moulton, which comes in both fixed-frame and separable-frame versions.
While BMX bikes also have ETRTO 406 mm wheels, they are not normally categorised as "small-wheel bikes".

History

An early proponent of small-wheeled adult bicycles was Paul [de Vivie], better known by his pen name "Vélocio". His approach was to use a balloon-width tire of about 57 mm on a 500 mm rim, giving a wheel of approximately 600 mm in diameter.
The man credited with being the father of modern small-wheel bicycles is Alex Moulton who pioneered the field with his F-framed Moulton Bicycle in 1962. His original small-wheeled design notably featured full suspension. Raleigh introduced the RSW-16 as a direct competitor, but it lacked the suspension of the Moulton and compensated for this by using very wide 50 mm "balloon" tires. The RSW-16 "Compact" was a folding version. In 1968 Raleigh introduced the Raleigh Twenty, which later went on to become one of Raleigh's biggest sellers. A large number of European manufacturers made U-frame small-wheeled and folding bicycles in the 1970s.

Advantages and disadvantages

Smaller wheels are more maneuverable. For this reason, and in some cases for comic effect, they are used in some clown bicycles. Smaller wheels more faithfully follow the terrain, giving a harsher ride on bumpy roads that are effectively smoothed by larger ones. It may be desirable for bicycles with smaller wheels to also be fitted with some form of suspension to improve riding characteristics. Bicycles with small wheels normally have their gearing adjusted to provide the same effective wheel radius as large ones, so pedalling cadence is not different. Smaller wheels tend to weigh less than larger ones, thus bringing the performance benefits of light wheels.
Small wheels, all else being equal, have slightly higher rolling resistance. On the other hand, they have lower aerodynamic drag due to their smaller area, which is proportional to their radius.

Length reduction

The overall length reduction of a bicycle using smaller wheels depends on several factors, but mainly the wheel size and whether the wheelbase is reduced. For example, keeping the same axle distance, and going from a 40-622 wheel to a 30-406 wheel will result in an overall length reduction of 236 mm. Theoretically that reduction may be doubled if bringing the wheels closer together by shortening the axle distance. However, a shorter wheelbase may result in twitchiness or poor stability.

Notable models