First results with Power2Max power meter

Bit of a palaver with the Power2Max this week.  It was delivered on Tuesday, so when I got home from work I was excited to fit it.  To save money I’d ordered the Rotor 3D+ cranks without chain rings, aiming to re-use my existing FSA chainrings, which, after all, are nearly new.  But they weren’t an ideal fit for the Rotor cranks – the FSA cranks are more ‘bent’ and so they have a longer chain catching stud, which does not fit behind the straighter Rotor cranks.  So I decided to order some oval Rotor Q rings.  These came on Friday, and…didn’t fit!  I hadn’t realised that I need special ones to fit around the bulky power meter/spider.  So I must return them and get them changed.  I’m impatient, so I fitted the FSA chainrings today, but with the chaincatcher not in the right place.  It’s untidy, but it works as a short term measure so long as the chain does not ship off the large chain ring.

If you’ve been following the blog you’ll be aware of my doubts about the accuracy of the TrainerRoad/Tacx Flow virtual power reading.  Well, today would be the day that I’d find out just how accurate it is.  I was pretty sure the actual power figure would be lower, but by how much?  I had pushed up my FTP to 282 virtual watts, what is the real figure?  I reckoned that anything above 250 watts would be a really positive result.  This afternoon I rode my hateful ‘hour of power’ session in order to find out.  I was unsure of what figure to aim for – the software had my FTP at 282 watts, so the target figure would be 101% of that, i.e. 285 watts.  But if that figure was significantly higher than reality, I’d soon run out of puff if I tried to ride at that level.  I know from experience that if you start this session too high, you have to back off, which is terrible for morale.  But I still have the Tacx Flow measurement available, not in the TrainerRoad software I use for recording (that has now been replaced by the power meter reading), but on the Tacx head unit.  This has correlated very well with the TrainerRoad reading in the past, so if I stuck to a reading on the Tacx that is manageable, I should be able to make it through to the end.  Below is a trace of the ride, and here is the link.

Screen shot 2013-04-06 at 18.05.20The figure I averaged for the hour long interval was 260 watts.  Chuffed!  You can see the blue shaded area is the target, which was the original 101% of FTP.  Of course I am below that.  I found that the Power2Max reads about 25-30 watts lower than the Tacx Flow, but the figures did not drift apart significantly.  This session was the hardest HoP I have done so far – my heart rate was 5 bpm higher on average than my recent efforts.  I kept it steady for the first 30 minutes, but as you can see from the graph, power dropped off in the second half.  Lactic acid!  But it’s amazing what happens when you get into the last 10 minutes.  You can see the end, and it doesn’t seem so bad. So I have reset my FTP to 260 watts and will be working using that number from now.  The next couple of weeks aren’t going to see too much training, because I have the Peterborough 105 mile sportive next Sunday, and the Saturday following that is my first ‘big race’!  I have also been a bit slack the past couple of weeks, too many social engagements.

Thanks for reading 🙂


Posted on April 6, 2013, in Training. Bookmark the permalink. Leave a comment.

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