topflightpro

I've had PT, Quarq and SRM pms.

In my experience, each gave me different numbers. 300w on a PT was much easier to hit and hold than 300w on the SRM. Quarq was in the middle. I also know it was much easier to hit very high sprint numbers on the PT than my SRM, though my highest recorded power came on the SRM. And when on the Kickr and using the Wahoo app, the Kickr numbers are usually about 5-10% higher than my SRM numbers.

At this point, I have SRMs on three bikes, and all three give me the same numbers.

I also now have a Stages that I took off my wife's bike before she sold it and doesn't fit on any of her other bikes, but I haven't used it yet, so I don't know where it fits into this.

TMonk

There's nothing wrong with it, which is why it's taken me so long. I'm just missing some functionality, like the ability to measure power with race wheels on (road or TT) , or to compare to my direct drive Saris H3 smart trainer

gsteinb

It's not like it's isn't an industry with a long and storied history of product issues, failures, and inaccuracies.

It's also important to point out that we're not even talking about something inherent in the meter itself but in the at homes calibration process. If one use a 50 pound weight that isn't really 50 pounds but +/- by some measure the number is different. Then there's the +/- 2% from there.

burnthesheep

I kind of want to make sure now the discussion stays with "real world" power. I think Zwift is so full of crap it can't be trusted for this discussion.

Case in point.....
So, just this week I was on Zwift doing an hour long sweetspot/threshold level interval. I was doing 265w nonstop on Richmond "fan flats". Avg speed on the road bike with the draft during this time was about 24mph or so. 265w being 3.75w/kg. As people pass you can see the color of the workout "zone" and see the power on the display as they pass. Then the board on the right shows their w/kg, so you can work out the weight. You can also see a symbol if they're doing a workout with erg mode by a symbol.

During that ride I pass a rider in a rest part of an interval, I assume. I think the color was grey. I glance and see they're doing like 230w in Z1. I think, whoa nelly, that's a lot of Z1 power. So, I workout the weight from their w/kg and they're between 220 and 240lbs.

They get into a work interval and the color changes to one of the non-VO2 zones but not tempo. Green? Yellow? As they pass I couldn't see the power.......but suddenly it's saying 5.3w/kg. They did this long enough to LAP ME on the fan flats course. So, like over 530w for over 20min. Possibly. They disappeared from the board, then reappeared behind me still at the same figures.

Not Zwift power with a curve on your fluid trainer, real meter.

Bull crap.

So, I disqualify Zwift from this discussion. I trust nothing I see on there any longer. Period. So, all the folks routinely doing 300w for 35, 45min at 100kg plus on Zwift..........I will say disqualified from counting. Same for 60kg folks on Zwift. Can't trust it.

TheKillerPenguin

Interesting, I find my G3 agrees with my Quarq dFour almost to the watt. I have no idea if my Direto is accurate or not, I only use it for terrain simulation (I pair my Quarq to Zwift for power).

furiousferret

I've recently thought you could sell a product that gives accuracy tests to certify power meters. For example, in Zwift Racing you bring in your trainer to be certified accurate and it picks up that SSN (which I'm not even sure exists) and Zwift knows its accurate power. For 'Championships' that and a weigh in the week of the race would be required, almost like a test proctor.

You could probably do it with an SRM and a pedal PM to compare the 3, but there would have to be a standard or people would argue the results.

topflightpro

I had PT SL 2.4, later updated to 2.4+. So, much older than the G3. My Quarq was also a second generation model, again, much older than the dFour. So, it's possible the technology has improved since I used it. (I also went through 3 Quarqs in 18 months, which is how I ended up on SRM, but that is another story.)

gsteinb

The weigh-in thing is forever a weak link in all this, and the reason I think the only way zwift becomes legit racing is doing in the same place real time like they run rowing regattas indoors. You can have massive shifts in weight. Gees until I moved here we had a hot tub and I sat in there about an hour a day. I could lose 7 pounds or more.

burnthesheep

Most recently, I'm pretty sure they shipped the same trainer to all participants from Garmin........the Tacx. So, you used what they shipped you. I can only find the "partner" literature right now, but there was an article floating around talking about the effort to send them out............either that or that was just a fever dream.

himespau 

The ZRL protocol of having you video yourself weighing yourself, then weighing some object (a weight, a gallon of water), then weighing yourself with the weight, then measuring your height all in one continuous video within 12 hours before or after your race is better than nothing, but I did a light 40 minute ride before bed last night and didn't drink as much as usual during the ride (didn't feel like I was working much) and my scales said I weighed ~1.5 lbs less this morning when I weighed myself than I did yesterday morning (drank a typical amount during the 3 laps of Whole Lotta Lava the night before), so, as you say, there is lots of room for gamesmanship. Of course, I'm a fatty, so there's a lot more room for play in my numbers (and small changes have less of an effect) than you folks with typical cyclists' bodies.

burnthesheep

If that's the case, yeah........do an easy Z1/Z2 ride 12 hrs before with no fan.......drop 3 lbs......weigh immediately........hydrate. That's over a kilo right there.

The other thing with the weighing an object like a weight is that most home scales probably don't have a good range for small weights like a 10lb dumb bell.

Whatever. I think I know my answer now is to not pay attention to almost anything on Zwift and not nearly as much "indoors" stuff that comes across my Strava also. Just pay attention to my own progress and consistency.

This week, doing well on time in zones. Just gotta do it tonight for the harder stuff and I'll be done for the week on the harder stuff (since Monday was harder also).

himespau 

Eh, racing is racing. Doing it with a team is fun. I know I'm not going to win, so I try to win my group or bridge to the next one, or not lose the sprint or whatever. I've sort of convinced myself not to care that not all the other people are racing fairly (hell, my powertap might not be fully accurate). Racing against some avatar on a screen that I can convince myself is a real person putting out a real effort is a helluva lot more fun than staring at a graph to see if I'm hitting my goals (though the latter is much better if I actually want to get better at this thing).

burnthesheep

I guess I appreciate the terrain in there for free riding when weather sucks. Sure, the structured training workouts I can toss on there from TP are nice. But being able to free ride for 2.5 hours indoors and not want to punch drywall out of boredom is great.

Also, learning to "world hack" has made me happier. Much fewer people in the world, so your bike speed is much more realistic without the crazy drafting. Also, tends to be fewer obvious cheats roaming around flying at 50mph. More peaceful.

Just put the code into the text doc of the world you want, and voila. Mostly empty France. Or one up everyone and go fully solo and get started then turn off the wifi. No weirdness. Just you.

As for group events, I only really do group rides with the group of folks I know and have a Facebook group with. That makes that more enjoyable. We have Discord channel going usually.

Enthalpic

I think the TT bike and workout mode have no draft effect if that's all you want.

burnthesheep

I seem to prefer the lonelier roads. I know my own effort is all it is if I choose the TT bike, and often do. Just that the world hack means fewer "high load" glitches in Zwift also. Like, you don't see all the weird flying bikes or people soaring off into the woods like you do sometimes in a really busy world.

For road bike, I'll often do something with an Epic KOM or Alpe climb. The w/kg and length of climb seems to somehow negate a lot of the weirdness where it is flatter. No idea why. Also that way I gain elevation towards the Tron bike.

Our Zwift group has a custom team kit on there that the blue Tron wheels would look awesome with!

TheKillerPenguin

I have heard stories of older Quarqs. Have to say dFour has been completely bombproof. And half the time its calibration number is 69. There are no drawbacks!

Toespeas

i would say on the road in a crit you wont actually do that because you are rotating but it should be pretty common to be able to produce 300 , thats not really that much , but again you will be rotating so you can hold 30 mph for the hour at around 225 but you will be surging up and down
on group ride pretty much the same , if you can find and hour climb or a climbing road race that seeing you have to produce more than 300 up the climbs you might average it , indoors it should be pretty easy depending on how accurate your power meter is , it will be about 25 miles per hour .
if you are talking 325 for like 5 hours then i will be unable to understand how thats possible but its said to be done by the elites !

sewupnut

Now that you mention it, I've got one working Cateye Solar left. Think I'll just start using it again.

gsteinb

This is like a cdr thread.Which particular you is averaging 30 mph for an hour crit?

topflightpro

East Coast Watts.

TMonk

OK cliff notes time, east coast guys can do 300w an hour no problem, west coast maybe, BTS hates zwift, zwift is nothing like real racing, and power meters are (sometimes) accurate.

jadocs

If the Stages is NDS and your pedals are dual, potentially there could be a difference (either high or low) depending on if your left leg is dominant or not. Not because the NDS PM is not accurate, but because it's only taking that one reading and applying it to the right as well. I have not met anyone who's L/R balance stays consistent in all conditions. In general if you are climbing at a high steady effort, L/R is pretty consistent, but when you throw variations in effort, level of fatigue, etc.... that's when the variation starts opening up and where you will see an effect on total power.

jadocs

You can't go wrong with these pedals. I used to be very hesitant about giving up my SPD-SLs, but honestly, I don't notice any difference clipping in or out. I also never had a problem with the pedal rotating on me when I tried to clip in (some people say that is an issue for them).

TMonk

I have heard a lot of good things about them! Thanks for the testimony.

jadocs

Yep, and with respect to my comment about L/R balance above....The Duos have what they call Instantaneous Angular Velocity (IAV). Other brands average the angular velocity and is why they cannot be used with oval chainrings. So if accurate total power is important, you can't go wrong.

https://cycling.favero.com/blog/tech...hats-iav-power