First post, long time lurker who has learned a lot from you guys (thanks, by the way). Been racing in Tucson for a couple years. I have been using the Stages PM (Ultegra) since January. I did a little "experiment" earlier this year and I'd be interested in what other's thoughts might be...

Indoor on trainer, maintaining constant cadence, single leg drills (1-minute long each leg) at multiple power outputs (40%, 60%, 80%, 100%, and 120% of FTP). With the PM only measuring left-leg power, assuming an FTP of 250, the results *should* be:

[TABLE="width: 300"]
[TR]
[TD][/TD]
[TD]Both[/TD]
[TD]Left[/TD]
[TD]Right[/TD]
[/TR]
[TR]
[TD]40%[/TD]
[TD]100[/TD]
[TD]200[/TD]
[TD]0[/TD]
[/TR]
[TR]
[TD]60%[/TD]
[TD]150[/TD]
[TD]300[/TD]
[TD]0[/TD]
[/TR]
[TR]
[TD]80%[/TD]
[TD]200[/TD]
[TD]400[/TD]
[TD]0[/TD]
[/TR]
[TR]
[TD]100%[/TD]
[TD]250[/TD]
[TD]500[/TD]
[TD]0[/TD]
[/TR]
[TR]
[TD]120%[/TD]
[TD]300[/TD]
[TD]600[/TD]
[TD]0[/TD]
[/TR]
[/TABLE]

If the power ouput for the left-leg only portion is higher than expected, this would mean my right leg is providing more power when pedaling with both legs. Conversly, if the power output for left-only is lower than expected, my left leg provides more power. This would also show whether my legs provide different %'s of power at differing power outputs.

When I did this, my results showed that my legs are within the PM's 2% accuracy of being equal -- which of course was of great dissapointment as I was hoping my embarrassingly low FTP could be explained by my power meter's innability to accurately account for my incredibly strong right leg.

The new PM from 4iiii might be another good option to look at if anyone else is in the market.