VEX V5 Drivetrains: Tank vs X-Drive vs Mecanum, and How to Choose Your Gear Ratio

1. The 2026-27 Motor Rules That Shape Your Drivetrain

Before you pick a drivetrain, know your motor budget. Under rule R10 of the Override Game Manual, the combined power of all V5 Smart Motors on the robot must not exceed 88W, counting the 11W and 5.5W motors and even motors that are not plugged in. Under rule R11, motors in Subsystem 2, the motors that power the mobile base, may not exceed a combined 55W.

What 55W means in motors

That cap allows five 11W motors on the drive, four 11W motors plus two 5.5W motors, or other mixes that add up to 55W or less. The remaining 33W or more of the 88W total goes to intakes, lifts and other mechanisms. Teams used to six-motor drives from earlier seasons need to rethink the layout. R11 also says drive motors cannot be switched to power anything outside the drive, and inspectors may ask you to demonstrate what each motor powers.

11W versus 5.5W motors on a drive

The 11W motor takes swappable gear cartridges: red 36:1 at 100 rpm, green 18:1 at 200 rpm and blue 6:1 at 600 rpm. The 5.5W motor has a fixed 200 rpm output and a 0.5 Nm maximum torque, against 2.1 Nm stall torque for an 11W motor with the red 100 rpm cartridge. The 5.5W motor is useful for filling the last 11W of a drive budget, but the 11W blue cartridge is what most competitive drives use for speed.

Why this makes X-drive more interesting

On the VEX Forum's drivetrain advice thread for new teams, an experienced member noted that tank drive remains the standard this season, but that the 55W limit has made X-drive more viable. When every team has the same drive power, the extra speed and agility of an X-drive matter more, though tank still wins pushing matches.

2. Tank vs X-Drive vs Mecanum: Which Drivetrain to Build

Here is how the three compare on the things that win matches. The short version: tank is the default, X-drive is a deliberate strategic choice, and mecanum is rare in V5.

Tank drive: the reliable default

A tank drive uses two parallel drive pods, one per side, with all wheels facing forward. The VEX Library's wheel guide notes that traction wheels are typically used in the center of a drivetrain to restrict unwanted sideways movement, and suggests combining them with omni wheels. Omnis let the robot turn smoothly; the traction wheels resist being pushed sideways by defense. Six-wheel tank drives with that mix are a common competition layout. Tank is the easiest to build square, the easiest to code, and the best at pushing, which matters in a contested endgame like Override's Midfield.

X-drive: fast and agile, but easy to push

An X-drive puts four omni wheels at 45 degrees in the corners. It can drive forward, sideways and diagonally, and turn while translating. Because each wheel pushes at an angle, a long-running VEX Forum discussion explains that an X-drive is in theory about 1.41 times faster than a tank drive with the same gearing, with roughly 0.71 times the force, by one poster's estimate. Real results depend on friction and robot weight. The costs: omni wheels everywhere means little resistance to being shoved, building four angled corner mounts accurately is hard, and the code needs holonomic math.

Mecanum: strafing with a traction penalty

Mecanum wheels have angled rollers that let a normally laid-out robot strafe sideways. The VEX Library lists 2-inch and 4-inch mecanum wheels. In practice, mecanum robots strafe slower than they drive forward, the rollers have less grip than traction wheels, and they tend to lose pushing matches. That is why mecanum drives are uncommon on V5 competition robots.

How to decide

Pick tank unless you can name the specific game task that needs sideways movement and you have the build time to make an X-drive rigid and square. Rookie teams should build tank, every time. A well-tuned tank drive with a reliable autonomous will beat a wobbly X-drive.

3. Choosing Wheel Size and Gear Ratio

Once the layout is decided, two numbers set your robot's personality: wheel diameter and wheel rpm. Faster gearing covers the field quicker but has less torque for pushing and accelerating, and makes precise autonomous movements harder.

The formula

Wheel rpm = motor cartridge rpm x (teeth on the driving gear / teeth on the driven gear). The driving gear is on the motor; the driven gear is on the wheel. Top speed in inches per second = wheel rpm x 3.1416 x wheel diameter / 60.

1. Pick a cartridge. Blue 600 rpm is the usual starting point for competitive drives; green 200 rpm suits a slow, torquey practice robot.
2. Pick a wheel size. VEX's wheel guide notes that larger wheels give more ground clearance, which makes it easier to drive over obstacles; smaller wheels sit lower.
3. Pick external gearing. For example, a 36-tooth gear on the motor driving a 48-tooth gear on the wheel turns 600 rpm into 450 rpm.
4. Calculate top speed with the formula and compare it to the 12-foot field.
5. Test with a full robot. If the drive stalls when pushing or overheats in a match, gear down.

Common setups, compared

The theoretical free speeds below come from the formula above. Real robots are slower because of weight, friction and acceleration, but the comparison holds. Combinations in the 360-450 rpm range on wheels of roughly 2.75 to 3.25 inches match what experienced members suggested in the VEX Forum thread for new teams.

Watch the heat

V5 motors protect themselves. VEX documents that stall current is limited to 2.5A, and as a motor reaches its temperature limit, its current is cut in steps to 50%, 25%, 12.5% and finally 0%. A drive geared too fast for a heavy robot will push hard for the first minute and then fade in the endgame, exactly when you need it. If your drive gets hot in practice matches, gear it down or lighten the robot.

Tune for autonomous too

A very fast drive is harder to stop precisely. Pair your drivetrain with an Inertial Sensor for turns (our V5 sensors guide explains calibration) and a simple PID loop, covered in our first VEX autonomous routine in Python guide.

Conclusion

Start with the rules: 55W for the drive, 88W for the robot. Then choose the layout that fits your game plan, which for most teams is a six-wheel tank drive with omni and traction wheels. Pick a wheel size and gear ratio in the 360-450 rpm range, calculate your top speed, and test with the full robot until it is fast without fading. Record each test in your notebook. For game strategy, read our Override game breakdown.

Want help building and tuning a competition drivetrain? Our in-store VEX classes in Cumming cover building, gearing and VEXcode programming. Contact us about upcoming VEX classes.

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