50.4 MB (2.9 MB compressed)
3597 x 4899 pixels
30.5 x 41.4 cm ⏐ 12.0 x 16.3 in (300dpi)
CORDELIA MOLLOY / SCIENCE PHOTO LIBRARY CORDELIA MOLLOY / SCIENCE PHOTO LIBRARY
Bicycle gears. Rear cogs for a bicycle gearing system, with the gear-changing mechanism (lower centre). The rear wheel spokes are also seen. The chain is wrapped over one of the cogs and through the gear-changing mechanism. The other end of the chain (not seen) is wrapped around the front cogs which are driven by the bicycle pedals (not seen). Turning the pedals rotates the front cogs, moving the chain and rotating the rear cogs, which then rotates the rear wheel and causes the bicycle to move. The different size cogs (6 at the rear, 3 at the front) allow 18 gears for different numbers of pedal rotations for one wheel rotation. Different gears are used for steep and flat roads.
Model release not required. Property release not required.