Powertap: what interval to display power

jhsidoc

I am trying to use my powertap pro for my SS, CR, Tempo intervals instead of HR and particularly when I'm out on the road vs. on a trainer the power measurements are all over the place. I can adjust the interval that the powertap averages the power for display (like 1,2,3,5, 30, 60 seconds of averaging) which is independant of how often the unit RECORDS the measurement. What have people foundto be the best averaging interval for the display so I won't drive myself nuts trying to keep my power in the particular zone?

frenchyge

Personally, I use 3 seconds. As you say, this doesn't affect the recording interval so it's largely personal choice.

beerco

I like to use the 1s mode. I like using the fast update because it gives me a chance to do something about what I'm seeing on the screen. I've tried using a much slower update and tend to oscilate between too high and too low (underdamped feedback for those who know what I'm talking about).

Be aware that the PT display will usually jump around by about +/- 15w depending on cadence. Your target power should be around the middle of the range you see. Using this method I can usually hit within 5w of my target power.

frenchyge

Also, be aware that the display still updates every second regardless of the averaging interval selected. IOW, the e.g. 3 sec average power is re-computed and displayed every second. Thus, you still have the opportunity to respond in a timely manner, but the fluctuations are dampened somewhat.

Personally, I'm chasing it too badly on a 1 sec averaging interval.

RapDaddyo

I use the shortest averaging interval for everything (watts, speed, HR) because (like beerco) I want to know what's going on real-time. I think there are other ways to avoid what I call "watt hunting." I manage power with cadence. After bringing my power up to whatever level I want at that point in time and getting in a gear that gives me my desired cadence, I settle in on a cadence and, until the road grade or wind changes, I then watch cadence more than watts. If I do need to increase or decrease power a bit, I use the 1% rule since I typically ride at a cadence of ~100rpm. So, if my target is 200w, every rpm is 2w. I don't worry about the typical sawtooth behavior of watts, even at a constant cadence.

rmur17

I use three sample averaging - even then it's a bit too jumpy for my liking - when compared to my TT bike and SRM.

As BeerCo alluded to, even if pedaling at a constant power output, the PT will display different wattages due to an 'precession' effect from the fixed sample rate. I just hate this. The SRM averages over complete CRANK cycles so this effect isn't there. He can explain this better than I

When doing intervals, I'd like to watch both current and average power - but neither the PT nor SRM does that. Or maybe just average power plus an Up/Down arrow to indicate whether you above or below average power.

If I'm working lower L4 or lower in power, I don't look at the display anyway. After riding on/off for too many years, I don't need a PM (nor HRM) to ride in tempo to lower L4 pace. I'll just check the average power display maybe midway thru the ride for some motivation coming home but that's about it. When on the mountain bike, I log average HR and check it 2-3 hrs into a ride. I never, ever look at it while riding. For solo/small group tempo rides, I invariably average 145bpm +/- 3bpm. 3bpm is about 10W on my Power/HR graph so that means I'm within 10W of midtange tempo power. That's plenty close enough for me.

I 'think' some folks read into AC's level's that you ought to stay in that 'zone' or consciously and continually modulate power to stay, for example, in the Tempo or 0.75-0.90IF range. That is not the case. You really don't need to stare at your PM that much Until you start doing intervals of course ....
Uhm but I guess this is well-covered in the new book ...

rmur

p.s. I should confess to looking at my PM during in-season recovery rides. I find it quite hard to stay even at lower L2 - let alone L1 without that feedback.

RapDaddyo

It should be clear to anybody who has read my post here or on other threads that I have spent and continue to spend a lot of time on what I'll call "power management." As anyone who has ridden with a PM for more than a few hours can attest, riding at a specific power over typical road courses (with constantly varying grades and wind conditions) is a non-trivial task. While some seem to have a good feel for their power without reference to their PM, I am not in that camp. I find that it takes a great deal of concentration to ride at a specific power, whether it is high or low relative to my capabilities. About the only two levels I can nail consistently without reference to my PM are the two extremes (flat-out and leg-weight only). Why I have spent so much time learning how to precisely manage my power on training rides and races will be apparent soon enough, but I'll just say at this time that I think it can be a competitive advantage. And as to your wish list for power data, that's about 10% of what I want.