The league allows three drive-motor families and four servo families. The manual names these size and form-factor families; a link on this page is a useful example, not the only version you may use. Gear ratio, speed, shaft length, connector, and rotation type still vary from listing to listing.
Check the official game manual before an event in case the rules change. The shorter allowed-parts summary mirrors the same list.
Quick comparison
| Part | Size and construction | Good starting use |
|---|---|---|
| N10 motor | Small metal gearmotor | Very compact, light mechanisms |
| N20 motor | Micro metal gearmotor | Small drivetrains, including the starter bot |
| TT motor | Larger plastic gearbox | Low-cost drivetrains with TT wheels and mounts |
| SG90 servo | Micro servo, plastic gears | Light arms, gates, and linkages |
| MG90S servo | Micro servo, metal gears | Small mechanisms that need tougher gears |
| MG995 servo | Standard-size, high-torque servo | Heavier arms and mechanisms |
| MG996R servo | Updated standard-size, high-torque servo | Heavier arms; the starter bot uses this family |
Allowed drive motors
N10
The N10 is the smallest allowed gearmotor family. It saves space and weight, but you will find fewer ready-made mounts and wheels than you will for N20s. Confirm the body and shaft dimensions before designing around one.
N20
The N20 is the easiest default for a small drivetrain. The same body is sold with many gear ratios, motors, encoders, shaft lengths, and lead options. Its listed voltage does not matter. Choose the speed and shaft your design expects, preferably with wires already soldered.
TT
TT motors are inexpensive and easy to mount, but their plastic gearbox is much larger than an N10 or N20. Use wheels and brackets made for the TT output shaft; N20 wheels do not fit it.
Motor links
The linked motors are examples of each legal family, not required models. For N20s, use the speed, gearbox, shaft, and lead style that suit your robot; the listing's voltage label does not affect whether the motor is allowed.
Allowed servos
The rules allow both positional and continuous-rotation versions of the four servo families below.
- A positional servo moves to an angle and holds it. Use this for an arm, scoop, latch, or steering linkage.
- A continuous-rotation servo spins in either direction. Its command controls speed and direction, not an angle, so it cannot hold an arm at 90°.
Read the listing carefully. Two servos with the same family name can have different travel ranges, and continuous-rotation versions can look identical to positional ones.
SG90
The SG90 is the light-duty micro option. Its plastic gears keep it cheap and light, which works well for mechanisms that do not take hard impacts.
MG90S
The MG90S keeps the micro-servo footprint and uses metal gears. Check the mount dimensions anyway; similar-looking 9 g servos are not always identical.
MG995
The MG995 is a standard-size, high-torque servo family. It needs more room and current than a micro servo, so test it under load before building the rest of the mechanism around it.
MG996R
The MG996R is an updated relative of the MG995 and is the family used by the starter bot. Standard and robot versions are sold with different travel ranges. For an arm, buy a positional version and verify that its package includes the horn and center screw your linkage needs.
Servo links
SG90 positional servo×1MG90S positional servo×1MG995 positional servo×1MG996R positional servo×1TowerPro warns that SG90, MG90S, MG995, and MG996R counterfeits are common. The family is what matters for legality, but an unreliable clone can behave very differently from the specifications in its listing. Buy from a seller you trust and test every servo before installing it.
N20 wheels
Wheels are unrestricted. The 43 mm rubber wheel below is the option used in the starter bot CAD, not a league requirement. Before buying any N20 wheel, match its bore to the motor's shaft shape, diameter, and length. Also check that the wheel diameter and width clear your chassis.
43 mm rubber wheels for an N20 shaft×1 pairBefore you order
- Confirm the exact allowed family name.
- For a servo, choose positional or continuous rotation on purpose.
- For servos, N10s, and TT motors, check the electrical requirements against your controller and battery. An N20 listing's voltage does not matter.
- Check the motor shaft, servo spline, mount dimensions, and included hardware.
- Compare gear ratio and speed only after you know the wheel or mechanism load.
Once the parts arrive, start with Making a motor move before installing them in a finished robot.
Product-identification images: N10 from Itgresa; N20 from DFRobot; 43 mm wheels from DFRobot; SG90, MG90S, and MG996R from TowerPro; and MG995 from ShillehTek. Representative TT motor photo by Adafruit, used under CC BY-NC-SA 2.0. The resized TT image is shared under the same license. Images were resized and placed on white backgrounds.