Rocket draws a bike with the pedals stuck right on the front wheel.
"No chain needed!" he says. "Push the pedal, turn the wheel."
Raven looks at her real bike. "What do you notice? Where are my pedals?"
They are in the middle, far from both wheels.
Nova hovers over the chain. "Something carries the turning from the middle to the back," she says. "Follow it."
Rocket's drawing is a real old idea!
On old high-wheel bikes, the pedals were attached right to the front wheel.
One turn of the pedals made one turn of the wheel.
Riders sat way up high over that big front wheel.
By the 1880s, chain drives were common.
With a chain, the rider can sit between two wheels for better balance.
The chain drive connects the pedals to the back wheel.
Your push on the pedals goes into the chain.
The chain carries it to the back wheel, and the bike moves forward.
| Part | Where it is | Its job |
|---|---|---|
| pedals and cranks | the middle of the bike | where your feet push |
| chain ring | front, by the pedals | the front gear that pulls the chain |
| chain | loops from front to back | carries the turning to the back |
| cog | on the back wheel | the back gear the chain turns |
Great tracing! Tomorrow we count gear teeth and make a prediction.