Please see the below post. I sent this inquiry to Quarq after purchasing a new ELSA 10R power meter from them. I had previous experience with a Quarq S975 Cinqo power meter but that unit had to be returned because I began to experience a lot of data drops. While I am waiting for a reply from Quarq I figured I would poll you guys and gals to see what you think. Any help and suggestions would be appreciated!
Sent to Quarq:
I just purchased an ELSA 10R. I recently returned the S975 model due to data drops. My question has to do with the zero offset calibration on the ELSA model. I have done about 10 rides on the ELSA to date (mostly indoor rides on a Kurt Kinetic road machine trainer using a Garmin 500). My procedure is to conduct a manual zero offset calibration prior to starting my training session (Drive side crank in the 6 o-clock position, unclipped). My reading is consistently around -195. I then start my warm up (15 minutes of light pedaling with two 1 minute higher intensity efforts). This takes about 20 minutes total. I then back pedal to conduct an auto zero calibration while on the bike prior to starting my intervals. When I do this it appears I have to work harder to generate the same wattage numbers as earlier in the workout. Kind of like the power meter is "warmed up" and giving different numbers. After noticing this I got off the bike and did another manual zero offset calibration (unclipped, drive side in the 6 o'clock position). My reading was about 20 units different -175. This training session was being done in a basement with a constant temperature of 65 degrees. This 20 unit deviation resulted in about a 10-15 watt difference for an identical effort (Same gear, same cadence, same indoor trainer, etc). According to your literature as long as the manual calibration numbers don't deviate more than 50 units then you are okay. I just want some direction from you guys as to what number is inherently more accurate. If I am doing an indoor training session and conduct a pre-ride manual calibration should I even do an auto calibration or another manual calibration during the session or was the first manual calibration the most accurate it will get? Or should I definitely do an auto zero calibration (by backpedaling 5 times) 10 or 15 minutes into my session to get the most accurate power numbers? It seems to me that the power numbers I was getting in the beginning of the session (after the pre-ride manual calibration but before the during session auto calibration) were inflated and that the numbers I was getting after conducting the auto calibration during the session were more accurate. Also I have checked to make sure my crankset is not loose and my chainring bolts are properly torqued (10 nm) since they are aluminum and my magnet is within 2-8 millimeters of the cadence sensor.