Can a power meter lose accuracy over time?

I have 3 stages power meters, 2 newish and one about 5 years old.

The older one reads about 15-20 watts lower than the new ones at all power zones, which I reckon is outside the ‘margin for error’ youd expect.

It works fine other than that, it’s consistent, doesn’t dropout any more than the new ones. But given the entire point of a power meter is consistency, if it’s not consistent with my other meters it’s probably not worth keeping.

Any thoughts?

How are you comparing the individual crank arms? Do you have another point of reference?

I would imagine that as it’s a strain gauge on a piece of metal that it’s sensitivity could indeed change with use.

You will get drift in strain gauges – though how much in the Stages I don’t know as I’ve never used one.

Can you check it? I used to manage T&E labs and had quite a good set up for calibrating them – done a fair few for people on here a few years ago.

No way to scientifically check other than on the tack flux, which is even less accurate than the stages!

What I do know is all my rides with it, overall and on individual segments, outside and on the turbo, I’m always showing less watts. Likewise, holding power I can usually manage easily seems alot harder.

I’ve had a number of stages and embarassingly have 4 at the moment…. 3 of them have been replaced under warranty at some point due to false 0w readings or huge 1 min long power spikes. I’ve had one read significantly lower than the others and 1 read significanlty higher than the others.

What I’ve come to believe is that the calibration figure tends to influence over / under reading. The ideal calibration number is 900. Over 900 tends to result in lower numbers and under 900 results in high numbers.

I did get one wet once (washed it without the batter door on it like div…) and the readings / calibration figures amplified my assunmptions until it dried out.

It’s a Stages – you didn’t ever have any accuracy to lose….

My 4iiii was running on battery fumes on 1st November, as a result I turned into an Olympic cyclist for the afternoon! 😆

On the whole stages aren’t accurate anyway

My 4 now track power very consistently against one another when compared with my wahoo kickr. I guess they could all be inaccurate but at least they’re all consistent with on another. Chances of that eh

ONe of mine started to drift a bit and I contacted stages customer support about it. Turns out the battery door and seal needed replacing and the unit needed to dry out inside a litte. Could be worth a try.

Stick them on the turbo and look at speed for power. They are probably all wrong but 15%!is well out of spec. 😉

My stages live in their box having all failed and I lost hope. Now running an SRM and an Assioma. They both read within 4% based on calibrated circuit rides. The Assioma agrees with my KICKR to within 2%.