Torque and speed are the same budget

Almost every mechanical decision in FTC comes back to one trade: speed or force, pick one. A motor produces a fixed amount of power, and gearing only decides how that power is spent.

The trade

Torque: Rotational force — how hard the shaft can twist. High torque lifts heavy things and pushes other robots.

Speed: How fast the shaft rotates, in RPM. High speed drives fast and cycles quickly.

A gear reduction converts speed into torque. A 3:1 reduction means the output turns one third as fast and produces roughly three times the torque. You have not created anything — you have exchanged one for the other.

Roughly, not exactly

Real gear trains lose about 5–10% per stage to friction. A calculated 3× torque increase is a ceiling, not a promise. Multi-stage reductions lose more, which is why a four-stage gearbox is noticeably less efficient than a single-stage one.

How to read a gear ratio

Count teeth. A gear with 20 teeth driving a gear with 60 teeth is a 3:1 reduction, because the driven gear has three times as many teeth:

ratio = driven teeth / driving teeth
      = 60 / 20
      = 3      → 3:1 reduction

Chain and belt work identically — count sprocket or pulley teeth instead.

Stages multiply. A 3:1 followed by a 4:1 gives 12:1 overall, not 7:1:

total = 3 × 4 = 12   → 12:1

Try it with your own numbers in the gear ratio calculator.

Applying it to a drivetrain

Drivetrain speed comes from three things: motor RPM, gear ratio, and wheel size.

wheel RPM   = motor RPM / gear ratio
speed (m/s) = wheel RPM × wheel circumference (m) / 60

A goBILDA 5203 at 312 RPM, direct-driving a 96 mm mecanum wheel:

circumference = π × 0.096 m ≈ 0.302 m
speed         = 312 × 0.302 / 60 ≈ 1.57 m/s ≈ 5.2 ft/s

The drivetrain calculator does this for you with a motor picker.

What speed should you actually pick?

Most competitive FTC drivetrains land around 4–6 ft/s. That is not a coincidence:

Below about 3 ft/s the robot feels sluggish and you lose scoring cycles.
Above about 7 ft/s it becomes genuinely hard to drive accurately, and you spend the match overshooting.

Rookies should aim low

A controllable robot scores more than a fast one. If you are choosing between 312 RPM and 435 RPM motors for your first season, take the 312. You can always gear up next year; you cannot get back the matches lost to a robot your driver cannot control.

Applying it to a lifting mechanism

Lifts are the opposite problem: you need torque, and speed is nice-to-have.

Ask two questions:

How much force do I need? Weight of the thing being lifted, plus the mechanism itself, plus a healthy margin for friction and binding.
How fast does it need to move? Usually "fast enough to not waste the match" — a lift that takes 4 seconds is fine; one that takes 15 is not.

Then gear for the force first and check whether the resulting speed is tolerable. If it is too slow, you need a stronger motor or a lighter mechanism — not a lower reduction, which would leave you unable to lift at all.

Do not gear a lift right at its limit

A lift geared to just barely raise its load will stall the moment anything binds, the battery sags, or you add a gram. Stalled motors get hot, draw huge current, and can brown out the whole robot. Build in margin — aim to use well under the motor's stall torque in normal operation.

The mental model

Think of a motor as a fixed budget of power. Gearing is how you spend it:

You want	Gear	You lose
A fast drivetrain	Less reduction	Pushing power, acceleration
A robot that wins pushing matches	More reduction	Top speed
A lift that raises heavy things	Much more reduction	Lift speed
A fast flywheel	Overdrive (ratio under 1)	Torque — it bogs down under load

Check yourself

Your robot's lift raises its load fine on a fresh battery, but stalls near the end of a match. What is the right fix?

You can now choose a ratio deliberately instead of by trial and error. The next lessons in this unit apply it to drivetrains, lifts, and intakes in turn.