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rmueller, are you asking about the usefulness of a power meter? I'm not training for anything currently, but I'm thinking of doing the Dirty Dozen ride in Pittsburgh in November. I don't have a power meter, and I'm not about to get one soon because I don't want to spend the money. But the power estimates from the GPS apps are useless, because they don't know what the wind was like. My times vary a lot on my commute, and the variation is due to wind more than anything else, because it's a flat, windy route. Or perhaps you're asking about this particular type of power meter. If it's not reliable, then I agree that it's useless.