Just started training with Power? Post your questions/comments here!
#4051
SkinnyStrong
Join Date: May 2010
Location: Austin, Tejas
Posts: 1,169
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
I don't get xPower in Golden Cheetah. I went out for ZCI intervals tonight, and paced them perfectly, no big spikes anywhere, just a bunch of flat tabletops. Yet xPower is 10 watts lower than average power on each interval. Is it because of the length of the interval, or what?
#4052
a runner no more
Join Date: Oct 2010
Location: Allentown, Pennsylvania
Posts: 261
Bikes: Raleigh Competition C6 Fusion
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I've never seen xPower < AP. Only thing I can think of is that since xPower uses a rolling average power, it would take in some of the low-power data from the rest interval. Normally, I would think that effect would be outweighed by the variability that tends to make xPower > AP. But since you paced your intervals so well, it's possible that it works out the other way around in this case. I think the averaging duration is ~30 seconds, which is 1/10th of your ZCI interval. A reduction by 10W (presumably, <3% of your power during the work intervals) is possible, especially if you took your rest intervals really easy.
That's just the mathematics. A better answer might be that xPower isn't particularly meaningful over a 5-minute interval. Stick with AP for short-duration power analysis.
That's just the mathematics. A better answer might be that xPower isn't particularly meaningful over a 5-minute interval. Stick with AP for short-duration power analysis.
Last edited by plantrob; 06-19-12 at 06:22 AM.
#4053
Senior Member
Join Date: Nov 2011
Posts: 183
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I've seen xPower below Avg Power. If you're at 100 w and your interval is 200, and well placed, it takes some time for your exponentially weighted moving average to rise to 200 watts, so for the first part of the interval, your EWMA is <200 (this is what is being averaged for xPower I believe). 10 watts seems high for a 5 minute interval, but I see them equal or xpower slightly lower on well paced intervals (usually on the trainer, I'm less well paced on the road).
That would be my guess, if I remember from reading Skiba's books correctly.
That would be my guess, if I remember from reading Skiba's books correctly.
#4054
Making a kilometer blurry
The big difference between XP and NP is that XP uses an exponential moving average (from the last 25s), where NP just uses the moving average (from the last 30s). I would need to look at the source code to know the value of α, which is the weighting factor for each sample in the EMA.
#4055
fuggitivo solitario
I've never seen xPower < AP. Only thing I can think of is that since xPower uses a rolling average power, it would take in some of the low-power data from the rest interval. Normally, I would think that effect would be outweighed by the variability that tends to make xPower > AP. But since you paced your intervals so well, it's possible that it works out the other way around in this case. I think the averaging duration is ~30 seconds, which is 1/10th of your ZCI interval. A reduction by 10W (presumably, <3% of your power during the work intervals) is possible, especially if you took your rest intervals really easy.
That's just the mathematics. A better answer might be that xPower isn't particularly meaningful over a 5-minute interval. Stick with AP for short-duration power analysis.
That's just the mathematics. A better answer might be that xPower isn't particularly meaningful over a 5-minute interval. Stick with AP for short-duration power analysis.
correct on both accounts. NP & XP don't start to tabulate until the 30th second (25th for XP), so that chunk will be missing
also correct that NP is useless for duration < 20 minutes
#4056
Senior Member
Join Date: Jul 2002
Location: Sacramento, California, USA
Posts: 40,865
Bikes: Specialized Tarmac, Canyon Exceed, Specialized Transition, Ellsworth Roots, Ridley Excalibur
Mentioned: 68 Post(s)
Tagged: 0 Thread(s)
Quoted: 2952 Post(s)
Liked 3,106 Times
in
1,417 Posts
Got an email from Training Peaks:
Is this a new feature?
After analyzing the data you uploaded into your TrainingPeaks account, we believe your threshold(s) have changed. Below are the threshold(s) we believe to be correct according to our analysis of your data:
Suggested Power Threshold: 315 watts
Current Power Threshold: 275 watts
These suggested changes to your threshold(s) have NOT been auto-applied. You can modify your threshold(s) to the suggested new value(s) within your TrainingPeaks account, under the Zones section of your Account Settings.
Suggested Power Threshold: 315 watts
Current Power Threshold: 275 watts
These suggested changes to your threshold(s) have NOT been auto-applied. You can modify your threshold(s) to the suggested new value(s) within your TrainingPeaks account, under the Zones section of your Account Settings.
#4057
Senior Member
Join Date: Aug 2011
Location: San Diego, CA
Posts: 109
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
#4058
These Guys Eat Oreos
Join Date: Jun 2010
Location: Superior, CO
Posts: 3,432
Bikes: Yes
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 13 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
#4059
Senior Member
Join Date: Jul 2002
Location: Sacramento, California, USA
Posts: 40,865
Bikes: Specialized Tarmac, Canyon Exceed, Specialized Transition, Ellsworth Roots, Ridley Excalibur
Mentioned: 68 Post(s)
Tagged: 0 Thread(s)
Quoted: 2952 Post(s)
Liked 3,106 Times
in
1,417 Posts
I think what they were telling me is "You're cheating to get a bigger TSS, so knock it off!"
#4061
Senior Member
Join Date: Apr 2008
Posts: 1,331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Newbie question
when someone says that person has a 1200W sprint are they talking average or peak ?
Also last night I found the interval feature on my Garmin under workouts. I was doing 250meter sprints then a 1.75km recovery. What I did was reset my Garmin after each set. I might be doing this incorrectly but it does work but am I throwing off my TSS. Each of my sets were in the 24-26 range so I can add them up but wil lthe nubmer be the same as if it was one workout.
when someone says that person has a 1200W sprint are they talking average or peak ?
Also last night I found the interval feature on my Garmin under workouts. I was doing 250meter sprints then a 1.75km recovery. What I did was reset my Garmin after each set. I might be doing this incorrectly but it does work but am I throwing off my TSS. Each of my sets were in the 24-26 range so I can add them up but wil lthe nubmer be the same as if it was one workout.
#4062
Senior Member
Join Date: Jun 2010
Location: Western MA
Posts: 15,669
Bikes: Yes
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Peak. After the peak, it goes in terms of 5 second power, 10 second power, 15 second power, etc.
#4063
Roadie
Newbie question
when someone says that person has a 1200W sprint are they talking average or peak ?
Also last night I found the interval feature on my Garmin under workouts. I was doing 250meter sprints then a 1.75km recovery. What I did was reset my Garmin after each set. I might be doing this incorrectly but it does work but am I throwing off my TSS. Each of my sets were in the 24-26 range so I can add them up but wil lthe nubmer be the same as if it was one workout.
when someone says that person has a 1200W sprint are they talking average or peak ?
Also last night I found the interval feature on my Garmin under workouts. I was doing 250meter sprints then a 1.75km recovery. What I did was reset my Garmin after each set. I might be doing this incorrectly but it does work but am I throwing off my TSS. Each of my sets were in the 24-26 range so I can add them up but wil lthe nubmer be the same as if it was one workout.
#4065
Bulldozer
Join Date: Jun 2006
Location: NYC
Posts: 2,846
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Many of the display metrics also include a 'lap' option. So, for example, if you're interested in seeing your lap power, you can set it to show 'Power - Lap' and it will display whatever you're averaging since you last hit the 'Lap' button. That's also especially useful for displaying time when you're doing intervals, so you don't have to keep track in your head of when you started and when you need to stop.
#4066
You blink and it's gone.
Join Date: Mar 2005
Location: Dundas, Ontario
Posts: 4,436
Bikes: Race bike, training bike, go fast bike and a trainer slave.
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Looks like my PT bearings may be on the way out, Noticed last night when moving the bike that there's a slight grinding sound coming from the rear wheel. My guess is the bearings are on the dry side. I need to remove the wheel and spin the axle by hand to check for roughness/resistance.
I'm thinking of attempting this one myself since the wheel is out of warranty, bought from Rob a couple years back. I know I risk buggering the calibration, but if I do then I send it in and wait for the bill.
I've got the bearing specs, but just curious if someone's knows where there's instructions on how to do this...Or what not to do so it doesn't get screwed...
I seem to remember a couple post in the 33 a while back from someone who did this exact thing.
I'm thinking of attempting this one myself since the wheel is out of warranty, bought from Rob a couple years back. I know I risk buggering the calibration, but if I do then I send it in and wait for the bill.
I've got the bearing specs, but just curious if someone's knows where there's instructions on how to do this...Or what not to do so it doesn't get screwed...
I seem to remember a couple post in the 33 a while back from someone who did this exact thing.
#4068
You blink and it's gone.
Join Date: Mar 2005
Location: Dundas, Ontario
Posts: 4,436
Bikes: Race bike, training bike, go fast bike and a trainer slave.
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I've been looking, but haven't found anything yet...video/picture wise..I'll keep searching...
#4069
Roadie
There are some directions here on WW for replacing the bearings
#4070
You blink and it's gone.
Join Date: Mar 2005
Location: Dundas, Ontario
Posts: 4,436
Bikes: Race bike, training bike, go fast bike and a trainer slave.
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Thanks Brian...I had found those...It really is pretty simple to get apart...
My freehub bearings are fine so I will leave those as is...
Now it's a matter of sourcing the bearings locally and pressing them in...I also found a youtube video that showed how to remove the axle and install the NDS bearing and axle...Looks easy enough...
I have no issues paying Saris to service the unit if there is actually something worn, but $300+ (plus the down time) for a bearing swap is a bit much....
My freehub bearings are fine so I will leave those as is...
Now it's a matter of sourcing the bearings locally and pressing them in...I also found a youtube video that showed how to remove the axle and install the NDS bearing and axle...Looks easy enough...
I have no issues paying Saris to service the unit if there is actually something worn, but $300+ (plus the down time) for a bearing swap is a bit much....
#4071
Making a kilometer blurry
Thanks Brian...I had found those...It really is pretty simple to get apart...
My freehub bearings are fine so I will leave those as is...
Now it's a matter of sourcing the bearings locally and pressing them in...I also found a youtube video that showed how to remove the axle and install the NDS bearing and axle...Looks easy enough...
I have no issues paying Saris to service the unit if there is actually something worn, but $300+ (plus the down time) for a bearing swap is a bit much....
My freehub bearings are fine so I will leave those as is...
Now it's a matter of sourcing the bearings locally and pressing them in...I also found a youtube video that showed how to remove the axle and install the NDS bearing and axle...Looks easy enough...
I have no issues paying Saris to service the unit if there is actually something worn, but $300+ (plus the down time) for a bearing swap is a bit much....
Last edited by waterrockets; 07-12-12 at 10:40 AM.
#4072
You blink and it's gone.
Join Date: Mar 2005
Location: Dundas, Ontario
Posts: 4,436
Bikes: Race bike, training bike, go fast bike and a trainer slave.
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Got the bearings replaced for a grand total of $35 and about an hour of my time...
Took the bike out today and everything seems to be working fine...Numbers make sense...
The only time I'll send the PT in is if the thing is actually not working...
The big deal for me is turn around time as well. Here in Canada the distributor is a little slow on the service and the last time mine went in I was without the wheel for almost a month...That's ok in the fall, but not now in prime racing/training season...
Took the bike out today and everything seems to be working fine...Numbers make sense...
The only time I'll send the PT in is if the thing is actually not working...
The big deal for me is turn around time as well. Here in Canada the distributor is a little slow on the service and the last time mine went in I was without the wheel for almost a month...That's ok in the fall, but not now in prime racing/training season...
#4073
Senior Member
Join Date: Aug 2006
Location: NOLA
Posts: 2,200
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
When iBike first came out I read a lot of scepticism on this forum. Given the current generation of iBike, is it a worthwhile power meter at this point in its development? I ride a road bike, a TT bike, a cyclocross, and a roadbike on a LeMond trainer. I'd like to transfer a power meter easily from bike-to-bike, and am considering an iBike Newton+ (which supposedly works on a trainer).
Also, I currently use a Garmin 705 with hrm, and would like to continue recording that data (I suppose I could always stick it in my jersey pocket on a ride rather than having two devices mounted on the bars). Can the Garmin receive the iBike power data via ANT+ so that its all in one file?
Finally, since the iBike uses wind as factor, is there any way I can determine drag with different positions on my TT bike to determine my most aero position?
Also, I currently use a Garmin 705 with hrm, and would like to continue recording that data (I suppose I could always stick it in my jersey pocket on a ride rather than having two devices mounted on the bars). Can the Garmin receive the iBike power data via ANT+ so that its all in one file?
Finally, since the iBike uses wind as factor, is there any way I can determine drag with different positions on my TT bike to determine my most aero position?
__________________
#4074
Senior Member
Join Date: Apr 2008
Posts: 1,331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
what are realistic percentages for improving each of the power metrics we use?
reason I'm' asking is I'd like to set some realistic goals for next year for peak, 5 second, 1 minute, 5 min and 20 min.
My soon to be wife says I'm crazy and set unobtainable goals so I'm asking you crazies...lol
right now my bests are 1125, 1063, 470, 293, 260 respectively.
I've never tested my peak, 5 second and 1 minute the numbers just from a rides and intervals I've done.
reason I'm' asking is I'd like to set some realistic goals for next year for peak, 5 second, 1 minute, 5 min and 20 min.
My soon to be wife says I'm crazy and set unobtainable goals so I'm asking you crazies...lol
right now my bests are 1125, 1063, 470, 293, 260 respectively.
I've never tested my peak, 5 second and 1 minute the numbers just from a rides and intervals I've done.