WhyFi

The person that you were addressing is one of the last persons that you should be lecturing about the uses of power meters and the degree to which accuracy is important for a given application.

RChung

On the internet nobody knows you're a dog.

guachi

If I had three bikes each with three different power meters A, B, and C and each power meter overstated power by 20% compared to the previous one and I was unaware of that would the lack of accuracy by at least two of the power meters have any effect on training or performance or anything at all?

If a power meter failed to accurately account for pressure or temperature changes (or whatever) and was off by, say, 10% from one day to the next and I was unaware of that would that have any effect on my training or performance or anything at all?

RChung

Depends on what you're doing with the data. If, as you say, you were unaware of the lack of accuracy, then you might think your performance sucked one day and soared the next, just because you were using a different PM that day. If you're using it to compete on Zwift, yeah, it would matter which power meter you were using. And, if you were doing some of the things I do, yeah, it would matter, too. But, frankly, not many riders do the things that I do.

Here's a pretty common situation: some riders have a smart trainer and then get a single-sided on-bike power meter, and they don't agree. Here's another common situation that happened to me: I had been using the same power for 5 years, then my bike got stolen. It took a little while to get the insurance money, and longer to decide on a replacement bike, and then to buy a replacement power meter. Suppose my new power meter read differently. Had I not known how to verify the accuracy of both power meters I might have had difficulty comparing my data before and after. (Since I do know how to verify accuracy, I knew the problem was me, not the power meter).

There are certain things you can do with power data that are quite reliant on accuracy and precision across the entire range of power. There are other things you can do that don't. Training FTP is one of the things that doesn't. That's why people have been able to train effectively with a regular training route and a wristwatch.

Doomrider74

Its not up to me to research some random profile on the internet: As RChung says, anyone can hide behind a profile.

If someone has legitimate knowledge and experience it is up to them to present themselves, and it, in a clear and concise manner.

Doomrider74

Mind if I ask why that is?

chaadster

It certainly could have an effect, yes.

Say, for example, your power zones are based on PM-A’s results, and your Level 2 / Endurance range is 168w - 225w. Going by your hypothetical variance numbers of PM-B and PM-C overstating PM-A by 20% and -40% respectively, a L2 ride of 200w on PM-A becomes an L4 / Threshold ride of 280w on PM-C.

Situations like where you’re planning for peak freshness for an event, or if you’re unable to complete prescribed workouts, or don’t understand that power output inaccuracy is the reason efforts have different physical impacts on different bikes and so you chase phantom explanations like diet or fueling or sickness, I’d say yeah, those are real effects.

SoSmellyAir

This may be off topic but to what extent can I get by with just a HR monitor and a cadence sensor? I don't have the latter yet; the reviews I have seen are hardly inspirational when it comes to accuracy.

Otherwise, I see that a lively debate has taken place during the time I actually spent riding my bike and then pigging out to replenish the approximate calories spent.

RChung

Ugh. That's a simple question but a full answer is complex.

I'll give a short answer now and you can do some research to fill in the details. The short answer is partly that FTP is only one summary measure of a specific type of performance, and that specific type of performance doesn't actually depend too much on exact levels of intensity. It appears, rather, that FTP is sorta more reliant on volume. (Conversely, there are other measures of performance that are more reliant on intensity than volume). We often use something like a dose-response model for training and performance but it turns out that to train FTP you don't need to titrate the dose very precisely.

A side effect of the expanded use of power meters is that since you could measure titrations pretty precisely, training plans and workouts have become more precise. Highly structured workouts can be distracting and give you something to focus on, especially when indoors on a trainer. They can make you feel like you accomplished something, and can check off that box. What's missing is the evidence that highly structured training produces better outcomes (in terms of FTP) than less structured training.

But there are things that do require high accuracy and precision in power data. It's just that most people don't do them.

BTW, you know who Andy Coggan is? The co-author of "Training and racing with a power meter"? The guy who coined the term FTP? Here's what he says.

RChung

I'm pretty concise.

Grouperdawg

My buddy has been riding them for a while testing, for what it’s worth they seem to be pretty accurate

chaadster

We need to be careful not to conflate structured, precise power meter training with improving FTP. The purpose of structured, precise training with power is to get maximum physical adaptation in a given time period. FTP is one marker of those adaptations, it’s not the point of the training, so assessing the value of structured training program based solely on “FTP outcomes” would be missing the point, it seems to me.

RChung

Depends on your goals and, to some extent, your disposition. Before I used power I tried using a HRM but couldn't quite wrap my head around the information it was telling me. Once I got power I stopped wearing the damn bra. Last year, because of COVID, I started doing a lot more indoor riding and pulled an old HR belt out of a drawer, changed the battery, and it still worked. So I've mostly but not slavishly been using it over this last year. I'm still not quite sure how to wrap my head around the information it's telling me.

Cadence is usually a red herring but maybe in conjunction with a HRM it could be marginally useful. It's a pretty weak carrier of information.

WhyFi

I recently got one o' them optical HRM arm bands - man boobage reduced by a good 87%, so it was definitely a good investment.

Doomrider74

Thanks for that. I guess I come from the mindset where inaccurate data is pointless data, rightly or wrongly.

Isn't it the case that imbalances between left and right legs can result in single-sided PMs being out by 10%+? I wonder how many of us have actually quantified our own imbalance so we can make the necessary corrections.

Its not as if single sided PMs are cheap, either: you're still paying 400-500 bucks. That may be less costly than dual sided, but I wouldn't call it cheap.

RChung

Ah. I come from a field where inaccurate data is an opportunity. Everyone has given up on those data so anything we can salvage is a plus. It turns out that even though bad data from cycling sensors are bad, they're still a lot cleaner than the stuff I'm used to working with so the statistical and analytical approaches that we developed for truly crappy data work pretty well on cycling data.

Yes, but the real problem is that bilateral asymmetry in pedaling isn't constant. There are times when it can be way off and other times when it can be not so much, and if you only have a single-sided device you can't know when that is. The important thing isn't that a device is close to the truth on average. The important thing is knowing when it is, when it isn't, and by how much.

Yeah. I just bought a used but very good condition PowerTap rim brake wheel for < $200. I know how and have what I need to verify that it's reading accurately and precisely (some of the things I do require accuracy and precision, and some don't) but not everyone does. That said, I try not to forget that not everyone has the same needs as I do. There are people for whom a single-sided PM makes sense, just like there are people who don't feel the need for power data at all. My wife has never been interested in power data. There's a hill near our house that she climbs maybe once every other week. She used to use her wristwatch; now she lets her phone app keep track of her time.

cuevélo

In case anyone missed it, it's not going to be this summer.

https://www.dcrainmaker.com/2021/08/...speedplay.html

RChung

The #1 rule of buying a power meter is: unless you have a really really good reason, avoid low serial numbers.

Rule #1B: never predicate a purchasing decision on an as-yet unreleased product. They don't even have serial numbers yet.

cuevélo

It's here.

https://www.dcrainmaker.com/2022/02/...er-review.html

https://gplama.com/2022/02/23/wahoo-...g-term-review/

https://cyclingtips.com/2022/02/waho...rollr-trainer/

Rdmonster69

I'm just here for the cocaine and the arguments LOL ....I thought this thread was about pedals. I however am like the old slow guy above. I do not need a power meter. I ride until I am breathing really hard, sometimes ...I sweat a lot too usually . That's enough for me LOL.

A power meter would probably just flash "give up ....give up" at me over and over.

I have mad respect for those that need and can use a power meter effectively.

As an aside a hundred years ago all athletes did things significantly different. There is certain allure to thinking cyclists from the old days would have been gods today with this technology. Maybe ....maybe not. Its difficult to train desire, will, natural ability and tolerance for suffering ....a power meter probably cant help with those things !!

phrantic09

Just lift weights bra’ - no more moobs

Fox Farm

After 22 years of using Speedplay, when they stopped providing replacement parts / cleats for the X series, and Wahoo's new offerings are pretty expensive, I moved on to Time. Should have done it a few years ago. I was very dedicated to Speedplay but I have to say that the Time system is better. And a lot less money. The much larger pedal base is better. I have two road bikes, four pair of shoes; to up grade to new Wahoo Speedplay at 180 x 2 for pedals and additional cleats at 50 each x 2 = 500. No thanks. Time Xpro 10 at about 90 each x 2 and additional cleats at 15 each x 2, no brainer. in the 80s and 90s, I used Look. These Time are better and the cleats don't wear out from walking on them - little raised nubs keep them off the ground and out of the mud. That was a real PIA with Speedplay. ok, flame me...

Sy Reene

Interesting story, but related to power meters how?

Fox Farm

just my disappointment in in what became of Speedplay with Wahoo ownership with poor customer support.

WhyFi

Man, the saltiness and sense of entitlement of some X-series users is something else. The X-series was long in the tooth and they took a backseat, way, way behind the Zeros, long before Wahoo bought them. Let it go.