How your effort reaches the wheel
Where your effort goes
Your legs turn the crankset. The chain carries that motion from the chainring to the rear sprocket, which turns the wheel.
Gearing in one sentence
A 44-tooth chainring and a 22-tooth sprocket: the wheel turns twice per pedal turn. Fewer wheel turns make climbing easier; more turns are faster on the flat.
Chain tension
With a derailleur, a spring swings the jockey wheels to take up chain slack as you change sprockets. With a hub gear one sprocket is enough, so the chain is tensioned once.
Which one?
A derailleur is light and efficient, ideal for gravel and mountain bikes. A hub gear is sealed and low-maintenance, ideal for year-round city riding.