SkippyKitten wrote:
Accuracy and precision are very good for starters with the G3. It’s also easy to install without needing calibration. For aero testing where you’re interested in the energy delivered to the tyre rather than output by the rider, hub PM means you can, pretty much, ignore gearing and transmission losses.
Yes it limits rear wheel testing choices, but the impact of rear wheel on the rest of the system is extremely limited, and in the few cases* where we’ve been looking at rear wheel options, we could still use another PM, but then you have to factor in transmissison loss and gear changes in test. We do test that way, but hub PMs are preferred.
* front end changes are normally more significant. Most riders have a deep section rear and disc and use the disc unless it’s not allowed, or really hilly.
Changing gear can affect the power accuracy of a Powertap as well (at a level that matters for aero testing). At least that's my experience when analysing such data from aero testing and is why when doing such testing we settle on staying in the same gear if we are using a Powertap.
Over the past decade or more of doing field testing indoors, I've never been let down by those with SRMs on their bikes. However I typically find with many other meters, while they still enable us to do good work for most aero testing stuff, they tend to provide data with a higher variability and so being able to nail down very small changes (e.g. an assessment of shoe covers) is harder or not possible or requires collection of so much data it's not cost effective for the time required.
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