On my road bike I’m riding an Ultegra left sided power meter from 4iiii. I’m using it for exact a year now, I never had any problems with it . I noticed since the last couple of weeks that my power meter starts overreading at random times. For example: on my cool down today the power meter was showing 300w while i was actually riding 200w. I stopped the ride and did a calibration. After that the head unit showed me the 200w as it was supposed to show me in the first place.
Last few days it displayed everything perfect, but today it was overreading sometimes. Every time i think it over reads it stop for calibration, but calibrating your power meter 4 times on a 4h ride is far from optimal. The battery is full, i calibrate my power meter every ride and there are no big differences in temperatures (taking your bike from a hot car outside for example).
Hopefully one of you guys can provide me of some useful information why this happens.
I had one a few years ago that worked OK (as well as you could expect a 1 sided meter to work) until midway through a ride it quit transmitting power, but still registered cadence. I replaced the battery before the next ride, and at first didn’t get anything at all, and then it started giving me really high and inconsistent numbers: soft pedal and it would register 2000-4000w, then sprint and power drops to less than 3 digits. I tried another battery and got the same results. Since I was dealing with a known and fairly significant L/R imbalance, I just gave up and replaced it with Faveros…
one thing you can try if you have not already is place the battery in the holder backwards for a few seconds then put a fresh battery in correctly. This might help if there is a capacitance issue.
4iiii offers a trouble shooting protocol on it’s website. When that didn’t work for my Dura Ace arm they replaced it at no cost. The problem was the arm separating, not the power unit. My symptom was also high readings.
Thanks for the reply. I replaced it with a new and better battery. The weird thing was, that those overreading only happend 2-3 times since last year. So it wasn’t a structural problem. And when it did some overreading, I calibrated the power meter and everything was solved. But sometimes it freaked out again a few days later. Since i replaced the battery it works just fine. I also don’t have a big imbalance in power out put between my right and left leg. 4iiii are great and cheap power meters but the quality is a bit dodgy if you ask me. Not in a way that the power numbers are incorrect (i have a dual Dura ace power meter on my TT bike and the numbers are highly comparable), but more in a way that they will break after a year or two.
Thanks for the reply! I also had a 4iiii power meter a few years ago (early gen i believe) and it also had some issues. I got a new one quite fast. Maybe my next power meter will be dual sided like a quarq or something like that.
Doing 2000w for just one leg is very impressive!! Ever considered track sprinting jokes aside, super weird when these power numbers are so high. Mine just did a very minor overreading compared to yours. Changed the battery with a new one and everything seems normal again. I also did a 5 min power test and the watts were correct. Thanks for the reply!
Doing 2000w for just one leg is very impressive!! Ever considered track sprinting jokes aside, super weird when these power numbers are so high. Mine just did a very minor overreading compared to yours. Changed the battery with a new one and everything seems normal again. I also did a 5 min power test and the watts were correct. Thanks for the reply!
This was from just a quick spin around the block after replacing the battery (and wearing flip-flops!):
And this is the moment it went bad a few days earlier. Just crested a climb, and when I started pedaling again I had cadence but no power:
I did a few rides where it only transmitted cadence without power, and then I changed the battery. From that point on, I had power but it was all over the place, often up in 4 digits, and with no correlation to my actual effort.
