It is a hub.
The material that is used to manufacture Continental bicycle tires is rubber made from the Uniroyal company or other companies that specializes in supplying rubber for bicycle tires. To get a more specific answer to the question, a visit to the local bicycle shop can render an answer.
A bike hub is mainly turned on a lathe. Spoke holes are drilled and if it's a hub brake or a rear hub there may be some milling too.
In the bearings that go between the stationary part - the axle, and the rotating part - the hub.
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Metals, plastic, maybe even a wooden handle.
on the rear wheel, at the hub. it's the bit that the chain runs over.
Who made this japan bicycle
The stem of a bicycle can be made from alloy, carbon or titanium.
Usually by having a special rear hub which measures the output of the rider.
polyp
No. there are quite a few other places where you can add an electric motor to a bicycle. However, the hub motor is quite probably the one which requires the least amount of changes to the rest of the bike.