Standard Conversion Factors

Known-good gearing values for common commercial-off-the-shelf swerve modules

These are known-good gearRatio/diameter values for common COTS swerve modules. Set them either as the drivetrain-wide default in modules/physicalproperties.json, or as a per-module override in a module's own gearing field (module-level gearing wins if both are present):

"gearing": {
  "drive": { "gearRatio": 6.75, "diameter": 4 },
  "angle": { "gearRatio": 12.8 }
}

• drive.gearRatio — motor revolutions per wheel revolution, as X where the ratio is X:1.

• drive.diameter — wheel diameter in inches.

• angle.gearRatio — motor revolutions per full azimuth revolution, as X:1.

The config generator at config.yagsl.com has these built in as presets — you generally won't need to type these by hand, but they're listed here for reference and for teams hand-editing JSON.

MAX Swerve

Pinion	angle.gearRatio	drive.gearRatio	drive.diameter
12T	46.42	5.50	3
13T	46.42	5.08	3
14T	46.42	4.71	3

Swerve Drive Specialties (SDS)

Module	angle.gearRatio	drive.gearRatio	drive.diameter
MK4 L1	12.8	8.14	4
MK4 L2	12.8	6.75	4
MK4 L3	12.8	6.12	4
MK4 L4	12.8	5.14	4
MK4i L1	21.4285714286	8.14	4
MK4i L2	21.4285714286	6.75	4
MK4i L3	21.4285714286	6.12	4
MK5i R1	26	7.03	4
MK5i R2	26	6.03	4
MK5i R3	26	5.27	4
MK4n L1	18.75	7.13	4
MK4n L2	18.75	5.9	4
MK4n L3	18.75	5.36	4
MK5n R1	26.09	7.03	4
MK5n R2	26.09	6.03	4
MK5n R3	26.09	5.27	4

Thrifty Swerve

Steering gear ratio is 25:1 for both configurations below (12T pinion, 3" wheel, NEO-driven). Check the gear-ratio chart on your Thrifty Swerve for other pinion/output combinations.

Output gear	angle.gearRatio	drive.gearRatio	drive.diameter
18T	25	15	3
16T	25	16.9	3

Plummer Industries

Configuration	angle.gearRatio	drive.gearRatio	drive.diameter
Corner, Mid Ratio	28	4	2.5
Corner, High Ratio	28	3.25	2.5

Deriving your own

If your module isn't listed, compute the reduction from the module's datasheet: gearRatio is motor revolutions per output revolution (drive → wheel, angle → azimuth), and diameter is the wheel diameter in inches, measured on a slightly-worn tread (a fresh, un-worn wheel measures larger than it will after a few matches, and using the worn number keeps odometry accurate longer). Overestimating diameter makes the robot think it's traveled less than it has, so odometry-driven autonomous routines undershoot; verify against a real drive-straight test as described in Verify Module Locations.