Metals are more durable than many other materials.
On early cars (and the wagons and carriages before them) the spokes were made of wood.
A clutch is a disc usually made of metal, with a hub, spokes, and sometimes springs. Some clutches are cone shaped.
Bicycle spokes are usually made of stainless steel, although cheap/old bikes might have spokes of galvanized steel instead. Some high-end bikes have thick spokes out of aluminum alloy. There are occasional uses of carbon fibre spokes too.
Tyres/tires are the rubber things that makes contact with the ground, they don't come with spokes. Rims are the (usually) metal hoops that the tyres/tires sit on, and they too usually don't come with spokes. Wheels consist of hub, spokes, and rim when you buy them. To make them rideable you need to add tyres/tires and tubes.
Because they allow for a sturdy and cheap structure to allow the mechanism to work. Plastic would be to weak (in the same price range) and wood would most likely rot! So cheap metal does the job just fine.
Bicycle spokes are usually made of stainless steel, although cheap/old bikes might have spokes of galvanized steel instead. Some high-end bikes have thick spokes out of aluminum alloy. There are occasional uses of carbon fibre spokes too. Titanium spokes are possible, but rare. Most spokes are straight gauge, with a mushroom shape and a bend at one end and about 1/2" of thread at the other. There are also straight pull spokes, which don't have the j-bend. Then there are butted spokes which are thinner down the middle than at the ends. More pricey, but usually good for durability and a bit of a weight reduction.
It is usually made from wood with a bridge made from metal. It is usually made from wood with a bridge made from metal.
Without spokes, wheels would have to be made from solid discs.
The metal spokes on my bike are about to brake.
The rim is made by forming a length of extruded aluminum profile into a hoop, joining it and drilling it for spokes and valve. Spokes are made by cold forging lengths of stainless steel. Nipples are usually made out of brass stock, then chromed/nickel plated. Hubs are forged and cut, usually out of aluminum, drilled for spokes and then have bearings and axles installed. Then hubs are laced to rims, everything is trued and tightened up and the wheel is done, ready to receive its tube and tire.
Spokes are the thin metal rods that run from the hub(the center of the wheel) to the rim( the hoop where the tire sits). Inches usually refers to the approximate size of the wheel, 20" for BMX, 26" for MTB, and 28" for road bikes.
Yes there are they are of a stronger metal than a push bike.
Most spokes are metal, and metals are conductors.