Chances of a faulty powermeter resulting in overtraining are virtually nil. Workouts are supposed to be tough. If you aren't occasionally failing to complete a targeted workout and they start too feel 'easy' it's time to raise your targets.

My experience is that virtual power on a trainer can be reasonably accurate to within +/-10% based on dozens of rides on a KK trainer with a PowerTap but it still moves around a fair amount depending on temperature, intensity of workout, temperature etc.

A stages meter will also vary significantly from day to day and intensity as the power balance in your legs changes. Bottom line is you've got two relatively coarse estimates of power and it would be difficult to draw any conclusions regarding the accuracy of either without a third independent more accurate reference.

Sample of one, admittedly. I've got power data for each leg with vector, and virtual two sided power with Quark. For me, there can be 2-3% difference just riding around. That shrinks to .1-.2% on intervals or hard efforts.

If you've got a 33% difference, it would be the result of an injury, or obviously noticeable disparity. I doubt anyone has such a difference minus some obvious issue observable without a power meter.

1-) You are not along, there are a lot of reviews out there where they ride with 3 power meters together and 3 head units and compare the results later. no noticeable difference for stages.

2-) Even if you have a discrepancy between legs, as you said 3%, it does not matter for your training. FTP is not ePenis... As long as you get consistent readings compared to your self, you can always achieve the workout that you intend.

This whole thread is non-sense to me.

Exactly. Go look on Zwift and see all the jerseys 'won' by the zPower people.

I use a Kickr with Zwift. I visually compared the power numbers from my Stages to the Kickr. I did not notice any glaring discrepancy. I did not, however, record both and graph them. I should do that.

Unless you're regularly putting out 25+ hour weeks, you don't need to worry about overtraining.

Better recreational cycling through electronics...

I'm just here for the toys... :innocent:

You don't notice a difference?
http://media.dcrainmaker.com/images/...wer_curves.png


I think the OP's problem belies your conclusion.

This is true if you're a pro or a trust fund baby. If you're like most of us with job/spouse/kid(s), overtraining can be an issue on fewer hours. OTOH, if you only have time to train 3-4 days/week, there's enough downtime in there to guard against overtraining.

If you have a job/spouse/kids and are obviously not riding a bike to make a living what are you training for to the point that you would be clueless enough to overtrain and hurt yourself?
"Sorry, I can't make it to work this week because I hurt myself due to a malfunction in my power meter"

Some people are:

1. Racing. Which requires training

2. Women. Who commonly need more recovery (ie are at risk of overtraining)

3. Masters. See comment #2

While others are:

A. Judgmental twits. Pick up a mirror

:)

In addition to what @heathpack wrote, some of us find training hard to be fun, and more fun is always better, right? :p It's not hard to fall into that trap.

Power meter malfunctions don't cause overtraining. Overtraining is the cycling equivalent of having a few beers too many and thinking you're ten feet tall and bulletproof...until reality steps in.

One of the main perks of using a powermeter for us working stiffs is to prevent overtraining. Personally, I'm inclined to ride myself in to the ground as I like working out, and I've used the PM data to make a conscious decision to back off or ride easier in more than a few occasions.

I would NOT trust a virtual power meter or estimates power meter data for reliable training data!


if you a take a given segment and ride it with a tail wind, no wind and head wind. Based on the times that you completed the segments you will get wildly different power meter numbers.


heart rate and speed can't estimate your power out numbers.

How does a powermeter prevent overtraining? Is there a universally applicable amount of work or stress that results in overtraining?

I think it's common to confuse over-reaching with over-training. Overtraining is rare among elite athletes and likely even less common among recreational athletes.

Overtraining is probably the least useful justification for an accurate powermeter.

A power meter provides an objective measurement of how much work you're doing. I don't think there's a universally applicable amount of work that results in overtraining, since we're all different. I'm 64, and trying to maintain a training schedule meant for a guy in his 20s would wipe me out in short order. But I can still do 700-1000 TSS weeks in a training block based on my FTP and recovery needs. FWIW, my builds are based on two-week blocks; this is a common practice among Master's racers.

I'm with you on the overreaching vs. overtraining thing. You can't improve without overreaching. The issue occurs when you think that if a little is good then a lot is better, and also think that recovery is for wusses. Elite racers don't overtrain because they use their power meters to quantify how much work they've done, and know when they've hit their targets and stop. Almost all of them have coaches to keep them honest.

I also think that overtraining is probably not an issue with the OP, but it's good that he's aware of the possibility.

For most people their motivation goes away before they are in danger of overtraining.

And I think for elite racers they don't use their powermeters to prevent overtraining, they just build downtime into their schedules. Because it's so individual there are really no guidelines for power (or work) that protect against over-training. Other markers such as resting HR being depressed, mood etc are probably better at detecting the early signs of overtraining. The accuracy of your powermeter is not important in detecting overtraining.

Must be my stages then...have this exact same set up and Stages is consistently 20-30 watts lower than Kickr...unless just soft pedaling.

In DC Rainmaker review there is a statement that team Sky even has similar issues against other known accurate power meters. So much so that they utilize an offset percentage for training with Stages in some cases.

Edit: This being said, it is consistent. So for training purposes as long as you stick with just Stages it should be fine.

Many people say this -- and they'd be right. But the real reason this is so is because training FTP is one of the least demanding applications for a power meter. That's why people have long been able to train successfully without a power meter. There are some things that are hard to do without accurate and precise measurements, but training FTP isn't particularly one of them. Many (but not all) riders aren't interested in doing those other things so for them a PM like the Stages will probably be fine. If you are interested in those other things, it won't be. No one (and that can sometimes include you yourself if you're first starting off with a power meter) can tell which group you fall into, or if your needs will stay the same over time or change.

This is the reason my new bike arriving soon will be with P2M rather than another stages. Stages appears to be a great meter for introduction to Power and good price but if you want some advanced metrics it has limitations.

There's a group of relatively low data quality but relatively inexpensive (nothing is inexpensive -- just relatively so) products on the market. A friend who's a coach calls them fine gateway drugs.

Nothing's perfect, and every power meter is trying to fill a different niche, so there's room for lots of alternatives, including gateway drugs. There are also some products that have relatively high data quality but are relatively inexpensive. I put the P2M and the PT hub in that group (I haven't analyzed data from the PT chainring yet so don't know whether it would fall into that group or not). Some people, even racers, will be perfectly happy with the Stages. Some people, even non-racers, won't. Racing category actually isn't a terribly good predictor of what you'll want or need or will be able to use.

To get back to the OP, he's got two relatively low data quality devices, the Stages and a trainer, and there's no simple way for him to know which is worse -- or if the problem is his legs. In his case, the discrepancy is large enough to be obvious. There are cases where the discrepancies may be small most of the time but large under certain circumstances, and not obvious. Lots of people appear to think that if something isn't obvious it can't be important.

A powermeter prevents over training by letting one compare Acute and Chronic training load values to make training decisions on the short-term. The amount of work or stress that results in over training depends on one's Chronic Training Load over a long period of time.

We may be saying "over training" when we mean "over reaching", but the difference in definition between the two terms are primarily based upon an arbitrary time constant, and as such it's not useful to differentiate between them for the purposes of this conversation. Yes, of course, over training is more severe and less common.

In a separate post you stated that for most people motivation would be the limiter, but I think that there are many "Type A's" out there that don't have that problem.

I plan my weeks (or usually 3-4 week blocks) out in advance, as it's part of the fun for me. Much of of the time I will end up using the data to consciously decide to back off at some point, as I tend to overexert myself. The PM has helped me manage performance for key events and/or prevent chronic injury from overtraining, which I am susceptible to.

The difference between over-training and over reaching is more than a time constant. Overtraining results in a set of physiological symptoms quite different than just being tired. These symptoms can't be identified by looking at CTL or ATL without having actually trained hard enough to bump into the region of overtraining and possibly correlating training load with the symptoms.

I suspect some can simply handle more training than others, some can handle 25+ hr training weeks that might cause others to overtrain. Building a CTL of 140+ with a steady diet of threshold intervals is different than getting the same CTL with higher volume but lower intensity.

I just think power and the metrics associated with training are second order metrics for identifying over-training.

Ah! So you do see how a power meter helps to prevent over training then :).

No one will argue with you that it's a second-order metric, at best. It's still a useful tool in this regard IMO.

Also, I could have been more graceful with what I was trying to communicate here:

Many cyclists in competitive circles, like rev. and myself, use the term "over training" somewhat loosely. True overtraining is quite rare and does have some physiological significance, I agree. If one tends to overreach for a few rides, say, a couple weeks' worth, when you're already fatigued in the first place, it can take a while to recover out of that TSB hole and actually be counter-productive to your long term fitness. Really it's just "fatigue", but we like to refer to it as "over training", potentially because the term has some clinical and prescriptive connotation to it. Many of the symptoms of true over training like chronic injury, illness, irritability can start to rear their ugly heads in this medium-term time view.

This is why we have felt that you are being so pedantic - because we chose to misuse the term :).