Rally and Vector Power Meter Advanced Torque Test

IMPORTANT: ADVANCED USERS ONLY
Great care and attention during test must be taken to ensure the data collected gives a meaningful result.

Rally and Vector owners can perform a static torque test on each pedal to see if it is operating within spec. The range should be +/- 2% of expected torque by hanging a known load on each pedal.

NOTE: Test is not required under normal circumstances to achieve accurate results with a Rally or Vector system. 

A mass of 25 lbs (~11 kg) or greater and a hook that will fit through the toe of the pedal will be needed for this test. To collect the data in order to perform the test:

1. Accurately weigh and record weight of entire mass in kilograms (weight, hook, rope, etc.)
   • Know the precise weight of all components to accurately assess the Rally/Vector’s performance
   • Use a scale that can reliably weigh all components to less than 0.5% (most scales will not measure the weight accurately enough to perform a valid comparison)
2. Put bike in a stationary trainer
3. Elevate bike so weight from pedal does not touch ground or support structure that bike and trainer are resting upon
4. Position bike as horizontal as possible
5. Power on compatible Edge device
6. Perform a static calibration

Below the Calibration Success message is a torque value in Newton meters (Nm).

NOTE: Vector and Vector 2 go into a “torque mode” after a static calibration to enable this test. Vector automatically exits the torque mode after a few crank revolutions, or 4 minutes – whichever occurs first.

To perform the torque test:

1. Attach mass to one of the pedals by placing hook through toe of pedal (see picture below)
   
   
2. Move to rear of bike
3. Slowly rotate wheel backwards to raise pedal to forward position – where crank is horizontal (This puts 100% of the load in the positive driving and maximum torque position)
4. Read torque value on Edge as you rotate wheel
5. Record highest sustained torque value
6. Move weight to other pedal, and repeat test

Garmin recommends performing the test 3 times on each pedal. Use the average of the readings for each pedal in assessing accuracy.

Compare the torque values the Edge reported with the expected torque value. Your expected torque value can be computed with the below formula:

Mass (kg) x gravity (9.81) x crank length (in meters) = expected torque (in Nm)

For example, if you used a 26.45 kg mass in your test, and your bike has 172.5mm cranks, your expected torque would be: 26.45 x 9.81 x 0.1725 = 44.76 Nm

See related content below to use the information gathered from this test to adjust your Rally/Vector Scale Factor accordingly.