Gear Range Matters More Than the Number of Gears

Bicycles are commonly described by how many gears they have. The number says almost nothing about whether the bike will climb a hill or hold a speed on the flat.

Range is the spread, not the count

What a drivetrain offers is bounded by its lowest and highest ratios. Everything between them is a matter of how finely that span is divided.

A drivetrain with many sprockets closely spaced may have a narrower range than one with fewer, widely spaced. The count is a resolution figure, not a capability figure.

Range is usually expressed as a percentage, comparing the largest ratio with the smallest. That single number tells a rider more than any sprocket count.

Steps between gears do a different job

Close steps let a rider hold a preferred cadence as conditions change slightly. This matters most at sustained effort on rolling ground.

Wide steps mean each shift produces a noticeable change in effort. On a city bike this is rarely a problem, because speed is being changed by traffic anyway.

The trade is unavoidable within a given range. More sprockets buy closer steps, not a wider span, unless the extremes change as well.

The low end decides whether hills are rideable

A bike's lowest ratio sets the minimum effort required to move at a given cadence up a given gradient. If that ratio is too high, no amount of fitness makes the hill pleasant.

Load makes this sharper. A bike carrying shopping or a child needs a lower bottom gear than the same bike empty, and the difference is not marginal.

Riders who find themselves standing on the pedals at low speed are usually short of range at the bottom, not short of fitness.

The top end matters less in a city than people assume

Above a certain speed, air resistance dominates and the effort required rises steeply. Very high ratios are only usable on descents or with a strong tailwind.

Urban riding rarely reaches those speeds and rarely sustains them. A top gear that is never used is occupying space in the range that could have gone to the bottom.

This is the argument for shifting a drivetrain's whole range downward on a transport bike. Nothing useful is lost and the climbing improves.

Comparing bikes needs a common measure

Gear inches and development are two ways of converting ratios into a comparable distance travelled per pedal revolution. Either allows two very different drivetrains to be compared directly.

Without such a conversion, comparing a hub gear with a derailleur system is guesswork. The sprocket counts describe different things entirely.

Doing the conversion once for a bike being considered takes a few minutes. It reliably explains why a bike that looked well equipped turned out to climb badly.