Danpj

So I did a ftp test today. Averaged 349 for 20 minutes. I'm 71 kilos so that puts me at 4.9 watts a kilo. I'm 17 and this is my second season of cycling. I find it hard to believe I can put out those numbers. I mean I'm fast but 4.9 watts a kilo would make me like cat 1 fast haha. I made sure it was calibrated correctly. I updated the firmware too. Is there anything else that would cause it to read high like that? I've never used any other power meter so I have nothing for reference.

HOWSER

Multiply your number by .95 to estimate your 1 hour FTP from a 20 minute test.

I'd suggest testing a few times to establish a baseline, then work from those numbers with your training.

greenlight149

Borrow someone else's pm, and compare.

Go to a steep hill, and see how fast you can go up it, plug in the info, including the gradient into a online calculator and see if its remotely close, since wind resistance is less of a factor when the hill is really steep.

Danpj

I took my data from the finishing climb of a race last weekend (went full gas up it) and plugged it into one of those calculators. It came out pretty close actually. And it actually estimated 20 watts above what my stages said. I'm gonna borrow a power tap and go for a ride and see if they give off similar numbers. Can you connect two power meters to an edge 510?

greenlight149

If it's fairly close then your pm is probably not that off, but ya compare to a power tap just to make sure would be a good idea.

I have no idea if you can connect two at the same time, but I don't think so.

valygrl

no, borrow another garmin too.

yankeefan

You're probably left leg dominant, which is skewing the power readings. As cliche as this sounds, consistency is more important than accuracy (in some regards) so it doesn't mean your Stages is useless. Also, Powertap usually gives lower numbers than crank arm/spider based power simply due to the physics of where the torque is being measured. You shouldn't worry too much unless the disparity is more than ~30 watts.

greenlight149

Oh right, forgot to mention this, I think 3% loss is typical through the drive train.

FLvector

You don't mention any software to analyze your data from the PM. Just looking at your 20 minute avg doesn't tell you much. By using Golden Cheetah, Training Peaks, WKO, etc. you'll be able to look at your data to see if this one ride was an anomaly. You should be able to look at your 20 min peak power, critical power curve, etc. This will help you to train for certain events and make sure you peak at a specific time during your training regime.

RChung

These threads make me sad.

_ediri

Why not? How far can it be off? 20-30 watt! Still good! You should be proud

Silvercivic27

Well, I guess he *thought* he didn't when he bought it, but it turns out he really *does* care about both precision AND accuracy, lol.

Danpj

I do realize when it comes to training it really is all relative. And the accuracy doesn't matter much as long as it's readings are consistent. Im just curious

cthenn

I have a left only crank PM, and wonder the same thing. It's very easy to see, sometimes I'll mess around and purposely pedal with my left leg only and then my right leg only, and the readings are extremely different. Of course they would be, but I wonder how much uneven pedaling can skew the accuracy. I guess it's true, only consistency is what matters, as long as I'm not doing 55/45 one day and 60/40 the next...

greenlight149

For some people the balance can change depending on the power output.

RJM

This would help you.

Your 349 puts you at 4.66 watts per kilogram if my calculations are correct.