Originally Posted by
bbbean
The reason is that it does a good job of what it is designed to do. It's an affordable way to reliably measure power. It's not as accurate as a two sided power meter but it is approximately 100% more accurate than no power meter.
Hmmm. What does "100% more accurate than no power meter" mean? Here's a plot of 10 rides I did up a little hill I have to go up pretty often, showing avg speed on one axis and avg power (from my calibrated power meter) on the other. As you can see, if I only had a wristwatch and no power meter, either speed or elapsed time would have been a pretty good predictor of power. The correlation was 0.97, and that includes one ride on a very windy day. So can you explain what "100% more accurate than no power meter" means? Cuz my current thinking is that it's as circular and meaningless as your original post.
It's certainly reliable and accurate enough for the vast majority of riders who want a power meter for fitness or racing. For those whose needs require the accuracy of a two sided PM, the extra $$$ is more easily justified.
I don't know what the "vast majority" of riders want or need, and I work with a lot of racers (and a few people who are just into "fitness"). I do know that there are differences in the data quality produced by different power meters, and that some riders can use high quality data and others don't. You appear to be among those who don't need high quality data, and there's nothing wrong with that. What's wrong is that you think everyone is exactly like you. The reason why Ray Maker's reviews are so long is that he thinks there's a use case for every product and he's not the arbiter for everyone else what their use case is. So he lays out the strengths and weaknesses and hopes that his readers will know their own use case well enough that they can navigate to the right choice among the many products he reviews.
But making pronouncements like you do is certainly faster and easier, so there's that.