Thanks to a member here I have a potential buyer already for my current Powertap SL+ wheel and even though he has already emailed me and expressed a desire to purchase this used wheel I wanted to give him some comfort about this used wheel set. It also gave me an opportunity to try something a little different than my usual at home bucket test that I have always used in the past. (Please know that I am not at the level of DC Rainmaker, Rchung, Tom A. and others when it comes to precisely evaluating equipment. Not even close to their level. So take my little test as just something entertaining, but at least I can give the buyer in a different state an idea that the hub does function and I think it is in good shape. The wheel and bearings are good too.)
Here is that rough test using a weighed bucket.
http://thecyclingaddiction.blogspot.com/2010/05/powertap-torque-test-rough-initial-test.html
http://www.thecyclingaddiction.blogspot.com/2012/01/2012-torque-test-garmin-800.html
The disclaimer to the test today was still not an accurate method because I did not use a certified weight. The weight I used was a 45 lb plate measure on the gym scale. I used that number which was 46.5 pounds. I tried this method that I had read in the past by placing the weight on the pedal at the 3 o clock crank arm position and rolling the bike slowly and by just a little back and forth and take the highest number shown on the computer. My old method was a fixed crank arm position as close to level as possible. I think I still like that method to be honest. Any little shift in the bike the numbers were constantly moving so it was hard to balance the bike in the most upright position and trying not to let is lean from one side to another. So I am still not sure if I got this part of the test perfect either. So now we are at two potential errors creeping in with a non-certified weight and keeping the bike in perfect position to get the prime number. Anyway here is the pictures from the test this morning.
Just a bit more information
I used my training bike for the test, C-dale six13 with an Ultegra 170 crank arm, 34 ring was used and a SRAM 11-28 cassette. For the computer I used a Garmin Edge 800 and reset the zero offset after each cog tested. The wheels tested were the PT SL+ hub that I am selling and the new G3 hub that I had built from a friend and picked up yesterday afternoon.
Saris method to the consumer to verify the hub is checking the zero offset value (Garmin display "Current Calibration") and I think their prime number is 512 with a certain acceptable range above and below by a few digits.
SL+ = 514
G3 = 507
Because I am selling the SL+ I will just state the results of this morning's test for that wheel. Both wheels tested fine as I expected with the zero offset values being within range of 512, but it never hurts to get some more practice testing the power meters.
SL+ test readings were: 22 Cog = 22.2 / 17 Cog = 17.6 / 13 Cog = 13.3
Balance not set yet, but just a picture of the scale and weight used in this test
The bike and two Powertap hubs being tested at my gym
I used my mountain bike pedal so that I could slip the plate on (my regular Look Keo pedal will not work)
Zero offset value for the PT SL+ hub
Notes from the data collected on each cog on the SL+ (sorry for the blur)
Here is that rough test using a weighed bucket.
http://thecyclingaddiction.blogspot.com/2010/05/powertap-torque-test-rough-initial-test.html
http://www.thecyclingaddiction.blogspot.com/2012/01/2012-torque-test-garmin-800.html
The disclaimer to the test today was still not an accurate method because I did not use a certified weight. The weight I used was a 45 lb plate measure on the gym scale. I used that number which was 46.5 pounds. I tried this method that I had read in the past by placing the weight on the pedal at the 3 o clock crank arm position and rolling the bike slowly and by just a little back and forth and take the highest number shown on the computer. My old method was a fixed crank arm position as close to level as possible. I think I still like that method to be honest. Any little shift in the bike the numbers were constantly moving so it was hard to balance the bike in the most upright position and trying not to let is lean from one side to another. So I am still not sure if I got this part of the test perfect either. So now we are at two potential errors creeping in with a non-certified weight and keeping the bike in perfect position to get the prime number. Anyway here is the pictures from the test this morning.
Just a bit more information
I used my training bike for the test, C-dale six13 with an Ultegra 170 crank arm, 34 ring was used and a SRAM 11-28 cassette. For the computer I used a Garmin Edge 800 and reset the zero offset after each cog tested. The wheels tested were the PT SL+ hub that I am selling and the new G3 hub that I had built from a friend and picked up yesterday afternoon.
Saris method to the consumer to verify the hub is checking the zero offset value (Garmin display "Current Calibration") and I think their prime number is 512 with a certain acceptable range above and below by a few digits.
SL+ = 514
G3 = 507
Because I am selling the SL+ I will just state the results of this morning's test for that wheel. Both wheels tested fine as I expected with the zero offset values being within range of 512, but it never hurts to get some more practice testing the power meters.
SL+ test readings were: 22 Cog = 22.2 / 17 Cog = 17.6 / 13 Cog = 13.3
Balance not set yet, but just a picture of the scale and weight used in this test
The bike and two Powertap hubs being tested at my gym
I used my mountain bike pedal so that I could slip the plate on (my regular Look Keo pedal will not work)
Zero offset value for the PT SL+ hub
Notes from the data collected on each cog on the SL+ (sorry for the blur)