2012 Torque Test - Garmin 800

Time to test the equipment and this is my first time checking using the Garmin 800 as the head unit. The end result of the reflects a 5% error, but I must admit I was rather hasty in going through this rough torque test. I believe my Powertap hub is within the acceptable 2% range and will try this test again with more accurate measured weight rather than the loaded bucket measured on a non calibrated scale and take a bit more time performing the test.

Considering using accurate weights and setup for the test the process below using the Garmin 800 (Garmin 500) to perform the test. See the previous test that I performed in 2010 for the Powertap Cervo or for additional photos during a rough torque test.

http://thecyclingaddiction.blogspot.com/2010/05/powertap-torque-test-rough-initial-test.html

Setup Tool

Bike Settings

Bike Profiles

Select Bike

Select ANT+ Power

Select Calibrate

Check Calibration and Zero Torque

Measured Weight Source

Level Crank Arm

Stick used to keep wheel from spinning

Torque displayed in newton meter

Measured Weight: 53.2 lbs

Crank Length: 170

Crank Ring: 34

Measured torque  =  (weight in lbs)  ×  (crank length in mm)  ×  (1 in/25.4 mm)  ×  (cog teeth/chainring teeth).

Measured Torque for 15 Cog = 157.09

CPU Displayed Torque for 17 Cog = 16.81 newton meter = 148.7811 pound force inch*

5% diffference

* Convert newton meter to pound force inch: (16.81 x 8.85074 = 148.7811)

Measured Torque for 22 Cog = 230.39

CPU Displayed Torque for 22 Cog = 239.76

4% difference

Spreadsheet Tool (Select tab for Powertap Cervo or Garmin 800)