Hello, I have had a service ticket open for 34 days now and it has been 16 days since I have gotten any response from Zwift.
I have a new Zwift hub one (bought in early October) that is reading low power by 6-8% once it is warmed up. This is checked and proven on nearly every ride against my Assioma pedals. I have also tested against a Stages power meter and both of those devices have been proven accurate against multiple Kickr’s and Stages SB20 bike. I have attached one image of a test where it is clearly off. I have dozens of compares to show this.
I have seen allot of new reports from Zwift hub owners that the release of the hub one in October has caused the hub to under report power. This seems to be a broader issue and I have yet to hear anything from Zwift on it.
I’m posting here it hopefully get some response/resolution from Zwift and get some comments to see how big/broad this problem could be. I’m pretty disappointed I can’t get Zwift to even response to my support emails on this topic. Everything about the trainer is great except this issue and this issue is a show stopper for me. Losing 6-8% late in races due to trainer power drift is not acceptable on a trainer that is advertised and +/- 2.5%. Hopefully Zwift can resolve it with some firmware changes.
You’re comparing a device that measures power at the pedals with a ±1% accuracy, and a device that measures power at the hub with ±2.5 accuracy. Its highly unlikely that they will ever agree, especially since you need to include the approximate 3% power loss your bikes drive train introduces between pedals and hub.
Mark, I understand your point but that is not the issue here. All of these same comparisons have been fine with the 5+ other trainers (4 Kickrs & Stages SB20) I have had on Zwift over the last 100,000 KM of Zwift riding. I have even retested with my kickr in the exact same way just to prove it is this trainer causing the shift. This issue is a hub accuracy issue. The hub is perfectly within spec for 15 minutes then loses accuracy as I ride longer. A 350 watt effort in the first 10 minutes of a ride is within the 2.5% spec. That same effort after 40+ minutes into a ride has the hub under-reporting power nearly 10% compared to the first effort. Attached are 2 images from the same ride. One is 350 watts at 8 minutes and one is 350 watts at 64 minutes. The Hub goes from 2% over to 6% under reading - that is an 8% shift in one ride. This is not drivetrain loss and this is not within the acceptable +/- specs of the devices being compared. The Zwift hub is the outlier here.
