The Wattage Thread
Discussion
Read what I posted.
Assuming your leg balance is perfect at every integer, its fine. But most peoples are not, and that only becomes more noticeable with harder efforts.
Lets say you are 46% one side like Ross above, stages will be doubling that and assuming both legs are equal. That's 8% error. Which is about 30W at threshold for me and a huge number of watts at any shorter intervals.
Assuming your leg balance is perfect at every integer, its fine. But most peoples are not, and that only becomes more noticeable with harder efforts.
Lets say you are 46% one side like Ross above, stages will be doubling that and assuming both legs are equal. That's 8% error. Which is about 30W at threshold for me and a huge number of watts at any shorter intervals.
Exactly, go and use a Watt bike (which is calibrated) or other PM to see what your split is. Mine drifts quite a bit depending upon output and how fatigued I am. I also have a fully rupture MPFL in my left need and G2 tear to my ACL so numbers do move about a bit.
Also interested in the value Quark PM's.....
Also interested in the value Quark PM's.....
I'd argue that consistency is more important than absolute accuracy. For most people power meters are tools to track performance gains and not to be certain that you can output 257.8 Watts for an hour. If you do have a L/R imbalance (which may be more pronounced during very hard efforts, then the error is always present and your progress is therefore measurable.
Example:
(1) Threshold effort (L/R = 48/52%)
Effort 1: Actual power = 250W, left leg power = 48% of 250W = 120W. Stages power = 120*2 = 240W (10W under-stated, or 4%).
Effort 2: Actual power = 270W, left leg power = 48% of 270W = 129.6W. Stages power = 129.6*2 = 259.2W (10.6W under-stated, or 4%).
(2) Sprint (L/R = 45/55%)
Effort 1: Actual power = 1000W, left leg power = 45% of 1000W = 450W. Stages power = 450*2 = 900W (100W under-stated, or 10%).
Effort 2: Actual power = 1200W, left leg power = 45% of 1200W = 540W. Stages power = 540*2 = 1080W (120W under-stated, or 10%).
So yes in both cases the stages will under-state the actual Watts; 4% in the threshold effort and 10% in the sprint effort. But the key is that as long as your left right balance remains the same for each type of interval then the Stages will consistently under-state your power, thus enabling you to measure your improvements. Or to put it another way, if you had a perfectly accurate power meter, your improvements would be as follows:
(1) Threshold - real improvement 20W, stages improvement 19.2W
(2) Sprint - real improvement 200W, stages improvement 180W
How would you adapt your training differently under the perfect vs. stages scenario?
Example:
(1) Threshold effort (L/R = 48/52%)
Effort 1: Actual power = 250W, left leg power = 48% of 250W = 120W. Stages power = 120*2 = 240W (10W under-stated, or 4%).
Effort 2: Actual power = 270W, left leg power = 48% of 270W = 129.6W. Stages power = 129.6*2 = 259.2W (10.6W under-stated, or 4%).
(2) Sprint (L/R = 45/55%)
Effort 1: Actual power = 1000W, left leg power = 45% of 1000W = 450W. Stages power = 450*2 = 900W (100W under-stated, or 10%).
Effort 2: Actual power = 1200W, left leg power = 45% of 1200W = 540W. Stages power = 540*2 = 1080W (120W under-stated, or 10%).
So yes in both cases the stages will under-state the actual Watts; 4% in the threshold effort and 10% in the sprint effort. But the key is that as long as your left right balance remains the same for each type of interval then the Stages will consistently under-state your power, thus enabling you to measure your improvements. Or to put it another way, if you had a perfectly accurate power meter, your improvements would be as follows:
(1) Threshold - real improvement 20W, stages improvement 19.2W
(2) Sprint - real improvement 200W, stages improvement 180W
How would you adapt your training differently under the perfect vs. stages scenario?
If I'm paying hundreds of pounds I want a device that is inline with other devices. Like it or not, people want to compare themselves to other people. For me its vital to really to have accurate numbers as working out the drag of a time trial position relative to your rivals (assuming you know they're on proper meters also) relies on that.
For £400 quid do I want something that is consistently wrong, or not? Easy answer for me.
For £400 quid do I want something that is consistently wrong, or not? Easy answer for me.
okgo said:
If I'm paying hundreds of pounds I want a device that is inline with other devices. Like it or not, people want to compare themselves to other people. For me its vital to really to have accurate numbers as working out the drag of a time trial position relative to your rivals (assuming you know they're on proper meters also) relies on that.
For £400 quid do I want something that is consistently wrong, or not? Easy answer for me.
Totally agree, if you need/want to compare with others. For most people though it's not important and the flexibility of Stages for swapping between bikes is a big plus.For £400 quid do I want something that is consistently wrong, or not? Easy answer for me.
I just took a quick look over my left / right balance history. It moves over time and also moves depending on position, as well as effort level!
The swings within the standard deviation are around 45% to 49% left leg. If using a Stages that is a whopping 24 Watts at 300 Watts. That is also the kind of gain I have been able to see and measure over the last few months of VO2 intervals. If I was trying to use a Stages, well basically I couldn't!
I say all of this as a Stages owner too. I have one on my least used mtb, it's perfectly acceptable on that for calculating TSS (once I have "corrected" the numbers). I suppose it could also be used for pacing somewhat as long as you were very aware of feel. I just don't think it could be used in any way to accurately measure gains. When I bought mine there was very little choice for mtb but as alluded to above that has now all changed. I wouldn't advise anyone to get a singled sided power meter.
The swings within the standard deviation are around 45% to 49% left leg. If using a Stages that is a whopping 24 Watts at 300 Watts. That is also the kind of gain I have been able to see and measure over the last few months of VO2 intervals. If I was trying to use a Stages, well basically I couldn't!
I say all of this as a Stages owner too. I have one on my least used mtb, it's perfectly acceptable on that for calculating TSS (once I have "corrected" the numbers). I suppose it could also be used for pacing somewhat as long as you were very aware of feel. I just don't think it could be used in any way to accurately measure gains. When I bought mine there was very little choice for mtb but as alluded to above that has now all changed. I wouldn't advise anyone to get a singled sided power meter.
I used to think stages was ok... until I did an FTP test that gave me 25w more than I'd ever managed previously despite the fact I hadn't really been training. And then I was unable to repeat the results with my powertap. Sold it soon after.
Good enough for some though, they all have their own unique downsides after all!
Good enough for some though, they all have their own unique downsides after all!
Just completed my first FTP test of the year managed 340w for 20 mins so puts me at 323w at the minute which I'm pleased with.
Had a really solid training block for the past 4 weeks and have another week to go before I have a week off (on hols) then back on it before the first race of the season on 9th April. This has also brought my weight down to 76.7kg so puts me at 4.21w/kg.
I'm getting on a bit (42 years young) but I'd like to try and get myself in the 340w -350w ftp range this season ... lets see how achievable that is.
Had a really solid training block for the past 4 weeks and have another week to go before I have a week off (on hols) then back on it before the first race of the season on 9th April. This has also brought my weight down to 76.7kg so puts me at 4.21w/kg.
I'm getting on a bit (42 years young) but I'd like to try and get myself in the 340w -350w ftp range this season ... lets see how achievable that is.
JEA1K said:
Just completed my first FTP test of the year managed 340w for 20 mins so puts me at 323w at the minute which I'm pleased with.
Had a really solid training block for the past 4 weeks and have another week to go before I have a week off (on hols) then back on it before the first race of the season on 9th April. This has also brought my weight down to 76.7kg so puts me at 4.21w/kg.
I'm getting on a bit (42 years young) but I'd like to try and get myself in the 340w -350w ftp range this season ... lets see how achievable that is.
Oof that's a good set of numbers!Had a really solid training block for the past 4 weeks and have another week to go before I have a week off (on hols) then back on it before the first race of the season on 9th April. This has also brought my weight down to 76.7kg so puts me at 4.21w/kg.
I'm getting on a bit (42 years young) but I'd like to try and get myself in the 340w -350w ftp range this season ... lets see how achievable that is.
I'm a mere 54-55kgs and 4.3-4.4W/kg with an FTP of 234W at the moment....though I'm due another test, I reckon I'm probably a few % higher now.
In other news....I've switched back to my summer wheels and tyres and bugger me the difference is comical. I reckon they're about 1.5mph faster. Did a tempo/sweetspot ride yesterday after a brutal session on the TT the day before, but the intensity factor was 0.87 (so working, but certainly not killing myself) and over 24 miles/1300ft climb I averaged 19.7mph which I was pleased with.
I know it's very slow compared to some of you guys but considering how hard I'd worked the day before, and the fact I felt pretty good, wasn't working that hard and had a few instances of having to slow for traffic etc, means I'm easily capable of doing a 20mph average without going too hard.
I have also put on about 1kg over the last 2 months or so, generally (I say generally
) by eating healthy foods and I've increased my carbohydrate intake and I do feel stronger on the bike for it, I think.Thanks, I'd say yours are a little better though! 55 kilo's is just so light ... born climbing machine. I'm probably not going to shed a significant mount of weight, maybe a couple of kilo's and power should increase steadily.
Well a the whole winter bike vs summer/spring makes a huge difference ... changing wheels and removing mudguards is a revelation.
I'm probably not going to shed a significant mount of weight, maybe a couple of kilo's and power should increase steadily. Well a the whole winter bike vs summer/spring makes a huge difference ... changing wheels and removing mudguards is a revelation.
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