INTERACTIVE GEARBOX VISUALISER

See what a gear change really does.

Watch the chain shift, then see exactly how your cadence and pedalling torque change. Find the awkward jumps in a cassette and learn how to change front rings without losing your rhythm.

YOUR DRIVETRAIN

Move the chain. Feel the difference.

Schematic view · not to scale

Choose a gear change to compare the difference.

BEFORE THE SHIFT

—

— rpm

At your chosen road speed

AFTER THE SHIFT

—

— rpm

At the same road speed

CADENCE CHANGE

—

THE DOUBLE-CHAINRING TRICK

Change front rings smoothly

Changing from a small to a large front chainring can cause a big cadence drop. This finds the rear sprocket that comes closest to preserving your current ratio, so you know what to shift at the rear too.

COMPARE THE STEPS

Where are the big cassette jumps?

Each bar shows the percentage your cadence falls if you shift to the next smaller (harder) sprocket without changing road speed. Select any jump to see it on the animated chain.

Small step (under 12%) Noticeable (12–16.9%) Large (17%+)

SET UP YOUR BIKE

Make it your gearing

Cassette & chainrings

Loading gearing…

Choose front chainring

Choose rear sprocket

Road speed18 mph

3 mph40 mph

Pedalling power (for torque comparison)200 W

50 W500 W

Your preferred cadence band

Low rpmHigh rpm

A GEAR CHANGE ISN'T A POWER SAVING

At the same speed, slope and wind, the road demands approximately the same wheel power regardless of gear. A lower gear raises cadence and reduces the average crank torque needed to produce the same power; it doesn't make a hill disappear.

Crank torque before—

Crank torque after—

Enter my own gearing

Front chainrings (1–3 tooth counts)Rear cassette (1–12 tooth counts)

Wheel size & calculations

Effective wheel diameter (mm)

The formula uses wheel circumference = π × diameter. Road speed is held constant for the cadence comparison; crank torque assumes your chosen power remains constant. Shifting itself involves no instantaneous speed change in this model.

WHAT YOU LEARN

Choose a cassette for your riding, not just its tooth range.

A wide cassette may provide excellent climbing gears but have larger steps between some sprockets. A tighter cassette may feel smoother when holding a steady pace. Use the jump map, cadence band and front-shift helper to understand those trade-offs before changing equipment. This schematic is educational and does not model chain movement timing, shifting performance or component compatibility.

Understanding cassette jumps and cadence changes

A bicycle gear ratio is the number of teeth on the front chainring divided by the teeth on the selected rear sprocket. At a fixed road speed, changing from a 19T rear sprocket to a smaller 17T sprocket raises the gearing and lowers cadence. If you were pedalling at 90 rpm in the 19T sprocket, the 17T sprocket would need about 81 rpm at the same speed.

Close ratios or a wide-range cassette?

Smaller percentage jumps make it easier to remain inside a preferred cadence range on rolling roads. Larger sprockets extend your climbing gears, but wide-ranging cassettes may involve bigger steps between neighbouring gears. With two chainrings, a rear sprocket change can offset part of the cadence change when you shift at the front.

Use the visualiser to compare those relationships before choosing a cassette. It models ratios and cadence, not the physical compatibility or performance of individual shifting components. You can also estimate a suitable climbing gear or read the gear calculation explanation.