The Wattage Thread

[Grandfondo]

Another Astana rider caught out!

[fromage]

okgo said:

Its HUGELY useful post race. Massive.

I couldn't care less about it during, unless in break, but after you can break your race down to the nth degree.

Ditto and looking at my power after a race a few times there have been junk data which was very annoying.

[BMWBen]

Did a ride to compare my stages and powertap yesterday, to see if the funny numbers that my stages have been giving me is because I've turned into a complete beast or if it's just because it's a bit broken.

Rode for 2:50 with my perceived effort at a comfortable Zone 2 level - for me with my FTP defined at 310w-ish that should be 170-230w.

FTP is actually lower than that at the moment, but not done a test for a couple of months so just left it there.

For the whole ride:
Average Watts on Stages - 231w
Average Watts on PT - 191w

Maximum on Stages - 780w
Maximum on PT - 633w

Cadence on Stages - 91rpm
Cadence on PT - 88rpm

Then for some select sections...
2 mins riding at what felt like threshold:
Stages - 400w
PT - 334w

etc. You get the picture. I'm a bit disappointed. Going by RPE it's the powertap that's correct. I've had both (different bikes, different BB types, different cranks, etc etc) for about a year, and when I first compared the Stages did read slightly higher, but it was 10-15w rather than this. It's too far apart to be useful. I'm going to test the stages with some weights/torque measurements and check it's not broken. If it isn't, then I'm going to have to get rid of it.

[anonymous-user]

That mirrors my experience with Stages. I have found my P2M similar to the PT but it is slightly slower on changes of cadence. A couple of club guys started posting bigger wattage after using Stages but their times over 10/25 didn't reflect the numbers.

Edited by anonymous-user on Sunday 23 November 10:08

[okgo]

I am embarrassed for stages. Bringing a product that st to market. Wow

[BMWBen]

okgo said:

I am embarrassed for stages. Bringing a product that st to market. Wow

Wanna buy it? I give you good price.

[drgav2005]

BMWBen - had you calibrated both Stages and PT before those numbers? I'm surprised the Stages numbers are so far out. My Stages values are within 2-4% or so of my Wahoo KICKR values. Maybe worth sending the Stages back if it is still under warranty.

[BMWBen]

drgav2005 said:

BMWBen - had you calibrated both Stages and PT before those numbers? I'm surprised the Stages numbers are so far out. My Stages values are within 2-4% or so of my Wahoo KICKR values. Maybe worth sending the Stages back if it is still under warranty.

Yup, calibrated both, both recorded on Garmins over Ant+ (different garmins, naturally). I'm going to do a torque test - it is still under warranty.

[Grandfondo]

BMWBen said:

Yup, calibrated both, both recorded on Garmins over Ant+ (different garmins, naturally). I'm going to do a torque test - it is still under warranty.

What was your average speed on the ride?

[Grandfondo]

BMWBen said:

Yup, calibrated both, both recorded on Garmins over Ant+ (different garmins, naturally). I'm going to do a torque test - it is still under warranty.

What was your average speed on the ride?

[BMWBen]

Grandfondo said:

BMWBen said:

Yup, calibrated both, both recorded on Garmins over Ant+ (different garmins, naturally). I'm going to do a torque test - it is still under warranty.

What was your average speed on the ride?

29.8 Km/Hr, ride was pretty flat, less than 300m of elevation gain.

Had to stop at 2 level crossings.

[anonymous-user]

For everyone who has got Stages and PT what have you found the peak readings like? I could always put out 10-15% more power according to the Stages. I know there are supposed to be drive train losses but....

[drgav2005]

BMWBen - there's definitely something wrong in that case! Hope you get it sorted quickly

[Grandfondo]

BMWBen said:

Grandfondo said:

BMWBen said:

Yup, calibrated both, both recorded on Garmins over Ant+ (different garmins, naturally). I'm going to do a torque test - it is still under warranty.

What was your average speed on the ride?

29.8 Km/Hr, ride was pretty flat, less than 300m of elevation gain.

Had to stop at 2 level crossings.

Looks like the PT is about right and the stages is pub power!!!

[BMWBen]

Grandfondo said:

BMWBen said:

Grandfondo said:

BMWBen said:

Yup, calibrated both, both recorded on Garmins over Ant+ (different garmins, naturally). I'm going to do a torque test - it is still under warranty.

What was your average speed on the ride?

29.8 Km/Hr, ride was pretty flat, less than 300m of elevation gain.

Had to stop at 2 level crossings.

Looks like the PT is about right and the stages is pub power!!!

Much as I wish that I could ride at 400w threshold, the reality is that it's roughly my 3 min power when I'm fit I'll keep the data on strava anyway though

[nacnac]

I did a comparison between my Powertap and Stages, it looked like this:

Duration	Stages Max	Stages Avg	PT Max	PT Avg
17 secs	975	731	995	751
1 min	518	386	531	420
7 mins	438	272	493	301

So then I got a friend of mine on my rollers to do another quick test:

Duration	Stages Max	Stages Avg	PT Max	PT Avg
1 min	130	113	126	108
2 mins	187	156	185	159

The conclusion I came to was that I have a leg imbalance and in general the Stages seems ok. However if I didn't have two power meters how could I draw that conclusion?

I will try to balance my power over the coming months and keep re-evaluating. In this sense buying the Stages has been useful to highlight a weakness.

[upsidedownmark]

Main weakness you've highlighted is that stages is flawed..

Do you kick a ball equally well with left/right feet? Are both arms equally strong? We're all typically a little unbalanced (perhaps not just physically ). The general conclusion so far seems to be that some degree of power imbalance is normal and within some percentage (which I can't remember, but I'm inclined to say something like 5-10%) is not worth worrying about.

Even then, stages is not useless, if your imbalance is consistent; it doesn't matter if stages counts double (or half), so long as it is repeatable; internet bragging rights aside it would be a valid training tool.

However, that's a big IF. In my experience, *my* L-R balance is not repeatable at all - extremes are 55/45 to 40/60 or thereabouts. I'd not be at all surprised if BMWBen's numbers turned out to be an imbalance.

PT to vectors, the PT picks up short accelerations better. I believe that to be down to magnet cadence vs accelerometer - the accelerometer appears to lag somewhat, I'd guess that it needs to heavily process the signal to derive cadence with accuracy. The vectors read a few watts higher in general, again expected due to position in the drivetrain. L/R balance appears to be mostly a random number generator, and is mostly ignored! You don't need L/R balance, but IMHO you need something that measures the total power, not takes one side and assumes you're evenly balanced / doubles it. With P2M priced that close, I don't understand why anyone buys stages, but there we go..

[bert11]

I have stages, rode with someone running PT on the weekend, his readings were consistently 5-10% lower than mine. So that echo's other peoples findings on this thread I guess. Still, the Stages is certainly helpful for training and pacing, just not comparisons with other riders.

And it's great not needing a special hub Left the rear wheel at the LBS for a week to get a new rim recently, but used a spare wheel and didn't miss a weeks worth of power data

[okgo]

nacnac said:

I did a comparison between my Powertap and Stages, it looked like this:

Duration	Stages Max	Stages Avg	PT Max	PT Avg
17 secs	975	731	995	751
1 min	518	386	531	420
7 mins	438	272	493	301

So then I got a friend of mine on my rollers to do another quick test:

Duration	Stages Max	Stages Avg	PT Max	PT Avg
1 min	130	113	126	108
2 mins	187	156	185	159

The conclusion I came to was that I have a leg imbalance and in general the Stages seems ok. However if I didn't have two power meters how could I draw that conclusion?

I will try to balance my power over the coming months and keep re-evaluating. In this sense buying the Stages has been useful to highlight a weakness.

Those numbers mean this product is not fit for purpose. Send it back. The difference is laughable.

Its not even data, its just garbage.

[fromage]

bert11 said:

I have stages, rode with someone running PT on the weekend, his readings were consistently 5-10% lower than mine. So that echo's other peoples findings on this thread I guess. Still, the Stages is certainly helpful for training and pacing, just not comparisons with other riders.

And it's great not needing a special hub Left the rear wheel at the LBS for a week to get a new rim recently, but used a spare wheel and didn't miss a weeks worth of power data

Not much point comparing your readings to others on the same ride unless they are the same weight and have a similar cda etc and you both have done exactly equal turns on the front etc

For example I rode with someone the other day and over a course of 60ish miles and 4600ft of climbing my average power was 179w and his was 215w but he is about 8kg heavier than me.

Stages really will only really work for someone has 50/50 power balance and has that throughout the ride as they fatigue etc