bicycles

Alarmed by this display of weapons, I looked toward the bridge and there saw, stretched across the near side, a cordon of policemen, their bicycles forming a roadblock before which stood several French officers in uniform and a small waspish man in a brown derby.

Hotel attendants pulled parked bicycles into the lobby.

Many industries, notably textiles, firearms, clocks and watches, buttons, horse-drawn vehicles, railroad cars and locomotives, sewing machines, and bicycles, saw expeditious improvement in materials handling, machining, and assembly during the 19th century, although modern concepts such as industrial engineering and logistics had not yet been named.

These bicycles were difficult to ride due to their high seat and poor weight distribution.

These models were known as dwarf safeties, or safety bicycles, for their lower seat height and better weight distribution ( although without pneumatic tires the ride of the smaller-wheeled bicycle would be much rougher than that of the larger-wheeled variety ).

File: Women on bicycles, late 19th Century USA. jpg | Women on bicycles on unpaved road, USA, late 19th Century

The more common types include utility bicycles, mountain bicycles, racing bicycles, touring bicycles, hybrid bicycles, cruiser bicycles, and BMX Bikes.

Less common are tandems, lowriders, tall bikes, fixed gear, folding models, amphibious bicycles and recumbents ( one of which was used to set the IHPVA Hour record ).

Unicycles, tricycles and quadracycles are not strictly bicycles, as they have respectively one, three and four wheels, but are often referred to informally as " bikes ".

Short-wheelbase or tall bicycles, when braking, can generate enough stopping force at the front wheel to flip longitudinally.

The great majority of today's bicycles have a frame with upright seating which looks much like the first chain-driven bike.

Such upright bicycles almost always feature the diamond frame, a truss consisting of two triangles: the front triangle and the rear triangle.

While some women's bicycles continue to use this frame style, there is also a variation, the mixte, which splits the top tube laterally into two thinner top tubes that bypass the seat tube on each side and connect to the rear fork ends.

For most of the history of bicycles ' popularity women have worn long skirts, and the lower frame accommodated these better than the top-tube.

Furthermore it was considered " unladylike " for women to open their legs to mount and dismount-in more conservative times women who rode bicycles at all were vilified as immoral or immodest.

Historically, materials used in bicycles have followed a similar pattern as in aircraft, the goal being high strength and low weight.

Most bicycles use a chain to transmit power to the rear wheel.

A very small number of bicycles use a shaft drive to transmit power, or special belts.

Some, mainly utility, bicycles use hub gears with between 3 and 14 ratios, but most use the generally more efficient dérailleur system, by which the chain is moved between different cogs called chainrings and sprockets in order to select a ratio.