Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

Using left crank power meter and now adding Garmin Rally pedal PM

Notices
Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Using left crank power meter and now adding Garmin Rally pedal PM

Old 10-20-21, 01:24 PM
  #26  
Seattle Forrest
Senior Member
 
Seattle Forrest's Avatar
 
Join Date: Mar 2010
Location: Seattle, WA
Posts: 22,257
Mentioned: 79 Post(s)
Tagged: 0 Thread(s)
Quoted: 15938 Post(s)
Liked 7,552 Times in 4,210 Posts
Originally Posted by Iride01 View Post
a consistently off by a certain percent PM will do just as well as another.
If that's how it worked, you would have your head unit automatically correct it. A power meter that's always exactly right but speaking in code like you describe would be fine. 🙂
Seattle Forrest is offline  
Old 10-20-21, 04:22 PM
  #27  
genejockey 
Klaatu..Verata..Necktie?
 
genejockey's Avatar
 
Join Date: May 2007
Location: SF Bay Area
Posts: 7,807

Bikes: Canyon Endurace, 105; Battaglin MAX, Chorus; Bianchi 928 Veloce; Ritchey Road Logic, Dura Ace; Cannondale R500 RX100; Schwinn Circuit, Sante; Lotus Supreme, Dura Ace

Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 4076 Post(s)
Liked 4,348 Times in 2,209 Posts
Originally Posted by RChung View Post
There are lots of things you can do with power meter data. Training is certainly one of them, but there are others. It turns out that training (especially training FTP) is one of the least demanding things you can do with power data (that's why riders have been able to train effectively with just a wristwatch and a regular training route since there have been wristwatches). There are things you can do with power data that you can't do with a Timex wristwatch. That you don't do any of these things and instead only do the simplest possible thing with power data is probably why you think that consistency is all one needs.

And, I don't look at that right hand panel and think "oh, that shows that one is consistently off by a certain percent." I think that's what the left hand panel shows.
Right. In the left hand panel, you can predict the value PM1 will give very closely if you know the value from PM2, but in the right hand case, for example, if PM2 shows 200W, PM1 might give you anything from 150W to 250W. Or something around 100W.

It's like having two watches, that not only don't always give the same time, but don't show a consistent difference - without other instrumentation, you have no idea whether either is accurate.
__________________
"Don't take life so serious-it ain't nohow permanent."

"Everybody's gotta be somewhere." - Eccles
genejockey is offline  
Old 10-21-21, 12:26 PM
  #28  
aclinjury
Senior Member
 
Join Date: May 2013
Posts: 660
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 496 Post(s)
Liked 167 Times in 126 Posts
Originally Posted by RChung View Post
That's a good and important question.

There are two ways to get faster: more power or less drag. I'm now at a stage of my life where my power is way down from my peak -- but I'm only a tiny bit down from my peak speeds. All this crazy stuff I do with power data? I have to do it or else I'd be even slower than I am.
I've always appreciated your tehnical discussions through the years on this and other forums. And I didn't mean to diminish your contribution value in anyway (if I came across like so).
Like you, i'm at a stage where I'm not as concerned with power numbers, doesn't mean I'm totally disinterested in them. But I feel like for the weekenders, there has to be a balanced perspective on the pursuit of their training goals (but this is only my personal value judgement).

I often wonder about this. Toward the end of many of my 10min or 20min intervals, I will find myself pedaling in squares, or shifting my butt as I try to finish the intervals. This is when the force going into the pedal change (based on my square pedaling). This probably affect muscle recruitment. This is one scenario that I wish to have good measurements and insight into how my pedaling techniques as I fatigue may or may not affect muscle recruitment.

Last edited by aclinjury; 10-21-21 at 01:50 PM.
aclinjury is offline  
Old 10-21-21, 12:49 PM
  #29  
PeteHski
Senior Member
 
PeteHski's Avatar
 
Join Date: May 2021
Posts: 2,165
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 1073 Post(s)
Liked 1,126 Times in 713 Posts
Originally Posted by aclinjury View Post
The real question is, can a more accurate PM on the market make a weekend athlete any better than a less accurate PM. I'm referring to weekend athletes, the people in this discussion. I doubt it. To this end, the discussion and dissection of PM... probably doesn't mean much for weekenders than say a pro pursuit cyclists. They should really stop pushing weekenders into buying PMs and into thinking that PMs will somehow enable them to do something that requires genetic blessing. No PM is gonna overcome a genetic deficit.
For me it's quite important that my bike PM correlates well with my indoor trainer PM. Fortunately they are always within a couple of percent and both are consistent. They could both be reading power in units of chicken-power for all I care. I find both PMs massively useful for both training and events and you would probably class me as a "weekender". The only bike I don't have a PM on is my mtb, as I don't really think it would be a lot of use for the casual trail riding I do on it. But on my road bike a PM really helps me to pace long Sportives and mountain climbs etc. I'm not sure anyone thinks a PM will enable them to do something that requires "genetic blessing" as you put it!
PeteHski is offline  
Old 10-21-21, 01:42 PM
  #30  
aclinjury
Senior Member
 
Join Date: May 2013
Posts: 660
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 496 Post(s)
Liked 167 Times in 126 Posts
Originally Posted by PeteHski View Post
For me it's quite important that my bike PM correlates well with my indoor trainer PM. Fortunately they are always within a couple of percent and both are consistent. They could both be reading power in units of chicken-power for all I care. I find both PMs massively useful for both training and events and you would probably class me as a "weekender". The only bike I don't have a PM on is my mtb, as I don't really think it would be a lot of use for the casual trail riding I do on it. But on my road bike a PM really helps me to pace long Sportives and mountain climbs etc. I'm not sure anyone thinks a PM will enable them to do something that requires "genetic blessing" as you put it!
I see your points, all valid. I consider myself a weekender. I used to train a lot 18 hrs/wk, and was holding 4.5-4.6 w/kg on an hour mtb climb (peaks over 7000 ft elevation). This would make me a solid cat 3 climber. But for me to maintain this w/kg, it requires a lot of training. Fast forward 4-5 years later, I've lost a bit of interest in all the structure training and power stuff. I hit the gym, packed on 5 pounds of muscles, and cut back my cycling hours to ~10 hrs/wk. And incidently this morning, I decided what the heck let's do a 20min interval, didn't really have a wattage goal for the interval at all, just went by leg feeling, and to my pleasant surprise, I keep the exact same power I did 4-5 years ago, granted i did gain 5 pounds, but I also felt like with the weight gain my "perceived effort" was a tad easier too. So, I guess what I'm sayin here is that, for my case, I didn't seem to lose much fitness after plateauing 4-5 years ago.

So now, I'm thinking, maybe after a certain point of training gains that your genetics have allowed, then the continual rigorous trainng and use of a PM... is probably a just like to give the same result as a loser training routine, and even without a power meter. That's why I asked the question earlier, "would a more accurate PM allow a weekender to train better than a less accurate PM". In my personal anecdote, I'd say... probably not likely.
aclinjury is offline  
Old 10-21-21, 07:53 PM
  #31  
Seattle Forrest
Senior Member
 
Seattle Forrest's Avatar
 
Join Date: Mar 2010
Location: Seattle, WA
Posts: 22,257
Mentioned: 79 Post(s)
Tagged: 0 Thread(s)
Quoted: 15938 Post(s)
Liked 7,552 Times in 4,210 Posts
Originally Posted by aclinjury View Post
That's why I asked the question earlier, "would a more accurate PM allow a weekender to train better than a less accurate PM". In my personal anecdote, I'd say... probably not likely.
Will I get bigger gains lifting at the gym where there's numbers on the side of each plate saying what it weighs, or picking up rocks in nature? DCRainman reviewed one that he said was fine up until about 600 w and then had no idea what's going on above that. That would be useless for sprint training for me. But most of the ones that are being sold are pretty good. 🙂
Seattle Forrest is offline  
Old 10-22-21, 02:00 AM
  #32  
RChung
Senior Member
 
Join Date: Sep 2009
Posts: 1,860
Mentioned: 31 Post(s)
Tagged: 0 Thread(s)
Quoted: 543 Post(s)
Liked 496 Times in 199 Posts
Originally Posted by PeteHski View Post
For me it's quite important that my bike PM correlates well with my indoor trainer PM. Fortunately they are always within a couple of percent and both are consistent. They could both be reading power in units of chicken-power for all I care. I find both PMs massively useful for both training and events and you would probably class me as a "weekender". The only bike I don't have a PM on is my mtb, as I don't really think it would be a lot of use for the casual trail riding I do on it. But on my road bike a PM really helps me to pace long Sportives and mountain climbs etc. I'm not sure anyone thinks a PM will enable them to do something that requires "genetic blessing" as you put it!
I care about whether they read in chicken-power because in order to test their accuracy, I measure the difference in reported power when adding a known mass, or climbing a known height, at different known speeds. It's a lot easier to do that in watts than in chicken-power.

Pacing can actually be important (but it's more about the distribution of work than raw power). One of the earliest things I learned from using power is that my previous pacing using RPE was way off. Having accurate power data (not just consistent) helped me to learn when to trust my RPE and when not to, so I learned how to "re-calibrate" RPE. That's especially important near threshold, so having accuracy near threshold was important to me.

Originally Posted by aclinjury View Post
I see your points, all valid. I consider myself a weekender. I used to train a lot 18 hrs/wk, and was holding 4.5-4.6 w/kg on an hour mtb climb (peaks over 7000 ft elevation). This would make me a solid cat 3 climber. But for me to maintain this w/kg, it requires a lot of training. Fast forward 4-5 years later, I've lost a bit of interest in all the structure training and power stuff. I hit the gym, packed on 5 pounds of muscles, and cut back my cycling hours to ~10 hrs/wk. And incidently this morning, I decided what the heck let's do a 20min interval, didn't really have a wattage goal for the interval at all, just went by leg feeling, and to my pleasant surprise, I keep the exact same power I did 4-5 years ago, granted i did gain 5 pounds, but I also felt like with the weight gain my "perceived effort" was a tad easier too. So, I guess what I'm sayin here is that, for my case, I didn't seem to lose much fitness after plateauing 4-5 years ago.

So now, I'm thinking, maybe after a certain point of training gains that your genetics have allowed, then the continual rigorous trainng and use of a PM... is probably a just like to give the same result as a loser training routine, and even without a power meter. That's why I asked the question earlier, "would a more accurate PM allow a weekender to train better than a less accurate PM". In my personal anecdote, I'd say... probably not likely.
I mostly agree, which is why I say that one of the least demanding uses for power data is training. That's why I keep saying that you can train pretty effectively with just a wristwatch and a regular training route, and why I think a single-sided power meter is fine for many riders. However, I think the real value of power data comes from doing things you can't do with a wristwatch, like drag reduction (but there are others, depending on what kind of weekend warrioring you do).

As an anecdote, I've never done 18 hrs/week of riding. The most I've ever done for an extended period was maybe 12 hrs/wk, and I was at my fittest. Then I changed jobs, and got married, and soon after we were expecting a child, so my riding time got cut a lot. That's when I bought a power meter. I was using the power meter not to get faster, but to learn how to cut out "inefficiency" in training time. I was able to stay very close to my former speeds and times on half as much riding -- but I couldn't keep it up for hours and hours as I had before. So I never actually got faster with power -- I stayed almost the same on half the riding. Now, of course, I'm much slower, and the kid is going to graduate from college next spring. So I'm old, fat, and slow; but if I do all these crazy things, there are times when I'm just old and fat.
RChung is offline  
Likes For RChung:
Old 10-22-21, 08:08 AM
  #33  
aclinjury
Senior Member
 
Join Date: May 2013
Posts: 660
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 496 Post(s)
Liked 167 Times in 126 Posts
Originally Posted by RChung View Post
I care about whether they read in chicken-power because in order to test their accuracy, I measure the difference in reported power when adding a known mass, or climbing a known height, at different known speeds. It's a lot easier to do that in watts than in chicken-power.

Pacing can actually be important (but it's more about the distribution of work than raw power). One of the earliest things I learned from using power is that my previous pacing using RPE was way off. Having accurate power data (not just consistent) helped me to learn when to trust my RPE and when not to, so I learned how to "re-calibrate" RPE. That's especially important near threshold, so having accuracy near threshold was important to me.



I mostly agree, which is why I say that one of the least demanding uses for power data is training. That's why I keep saying that you can train pretty effectively with just a wristwatch and a regular training route, and why I think a single-sided power meter is fine for many riders. However, I think the real value of power data comes from doing things you can't do with a wristwatch, like drag reduction (but there are others, depending on what kind of weekend warrioring you do).

As an anecdote, I've never done 18 hrs/week of riding. The most I've ever done for an extended period was maybe 12 hrs/wk, and I was at my fittest. Then I changed jobs, and got married, and soon after we were expecting a child, so my riding time got cut a lot. That's when I bought a power meter. I was using the power meter not to get faster, but to learn how to cut out "inefficiency" in training time. I was able to stay very close to my former speeds and times on half as much riding -- but I couldn't keep it up for hours and hours as I had before. So I never actually got faster with power -- I stayed almost the same on half the riding. Now, of course, I'm much slower, and the kid is going to graduate from college next spring. So I'm old, fat, and slow; but if I do all these crazy things, there are times when I'm just old and fat.
Right. In my experience, one of the major "advantage" of being able to train long hours per week is that:
1. your routine doesn't have to be "efficient" because you will gain fitness based on sheer volume. Of course, as a race or event approaches, you need to cut down the zone1/2 hours and start to focus on specificity (the greater the volume you had put in, the shorter amount of time you need to spend on specificity before entering peak fitness).
2. with a great volume base, you're considered well trained, then the rule "FTP = 95% of 20min max effort" applies. If not well trained, then this rule doesn't apply. And it seems from personal experience that it requires about 18-20 hrs/wk to be considered "well trained". Anything less then this, then you could still train to get a good threshold but you won't be able to do many above-threshold forays and still have something left at the finishline.

But I will say this. There are many research on exercise physiology already. All the training and response are pretty well researched (yes, you still need to understand your body because of specific individual response, but this can only be known after some experience, and maybe a good coach). However, the one area that is still not well document is diet. There isn't much research that say "if you eat this diet, you can expect to get this training response". If there is something I wish to know better, it's this aspect of training performance.
aclinjury is offline  
Likes For aclinjury:
Old 10-22-21, 08:22 AM
  #34  
aclinjury
Senior Member
 
Join Date: May 2013
Posts: 660
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 496 Post(s)
Liked 167 Times in 126 Posts
Originally Posted by Seattle Forrest View Post
Will I get bigger gains lifting at the gym where there's numbers on the side of each plate saying what it weighs, or picking up rocks in nature? DCRainman reviewed one that he said was fine up until about 600 w and then had no idea what's going on above that. That would be useless for sprint training for me. But most of the ones that are being sold are pretty good. 🙂
so you wanna be a sprinter? Sprinting is A LOT less trainable then threshold training. Meaning. It's a lot easier to take good sprinter and transform him into a decent climber than it is to take a good climber (or TT'er) and transform him to be a good sprinter. Sprinting requires more genetic blessing than climbing or TT'ing.
aclinjury is offline  
Old 10-22-21, 03:04 PM
  #35  
PeteHski
Senior Member
 
PeteHski's Avatar
 
Join Date: May 2021
Posts: 2,165
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 1073 Post(s)
Liked 1,126 Times in 713 Posts
Originally Posted by RChung View Post
I care about whether they read in chicken-power because in order to test their accuracy, I measure the difference in reported power when adding a known mass, or climbing a known height, at different known speeds. It's a lot easier to do that in watts than in chicken-power.

Pacing can actually be important (but it's more about the distribution of work than raw power). One of the earliest things I learned from using power is that my previous pacing using RPE was way off. Having accurate power data (not just consistent) helped me to learn when to trust my RPE and when not to, so I learned how to "re-calibrate" RPE. That's especially important near threshold, so having accuracy near threshold was important to me.
My threshold power is defined using the same "chicken-power units" as I ride with. So in that sense it doesn't really matter. But as it happens I don't think my PMs are far off measuring in actual Watts. So it's all good for my simple usage and pretty effective. I found the same with RPE. I tended to ride too hard when I was fresh and full of adrenaline. Now I pace long climbs much better and usually better than my friends who ride without power. I'm now pretty good at guessing what power I'm riding with too. I just have a single-sided Specialized/4iiii crank sensor on my road bike and an Elite OTS on my trainer. I've been impressed with both their consistency and agreement. The Elite consistently reads about 3-4% lower at my threshold, which is to be expected with drivetrain losses. I have compared them at steady power levels from 100W through to 350W and they are within that same 3-4% window, perhaps a little higher at very low wattage, but that doesn't bother me. I'm about to move onto a Kickr Bike for my indoor training this winter, so will be interesting to see how that compares on power measurement, but I'm not expecting to see a big difference.
PeteHski is offline  
Likes For PeteHski:
Old 10-22-21, 10:03 PM
  #36  
RChung
Senior Member
 
Join Date: Sep 2009
Posts: 1,860
Mentioned: 31 Post(s)
Tagged: 0 Thread(s)
Quoted: 543 Post(s)
Liked 496 Times in 199 Posts
Originally Posted by PeteHski View Post
My threshold power is defined using the same "chicken-power units" as I ride with. So in that sense it doesn't really matter. But as it happens I don't think my PMs are far off measuring in actual Watts. So it's all good for my simple usage and pretty effective. I found the same with RPE. I tended to ride too hard when I was fresh and full of adrenaline. Now I pace long climbs much better and usually better than my friends who ride without power. I'm now pretty good at guessing what power I'm riding with too. I just have a single-sided Specialized/4iiii crank sensor on my road bike and an Elite OTS on my trainer. I've been impressed with both their consistency and agreement. The Elite consistently reads about 3-4% lower at my threshold, which is to be expected with drivetrain losses. I have compared them at steady power levels from 100W through to 350W and they are within that same 3-4% window, perhaps a little higher at very low wattage, but that doesn't bother me. I'm about to move onto a Kickr Bike for my indoor training this winter, so will be interesting to see how that compares on power measurement, but I'm not expecting to see a big difference.
Coincidentally, that plot in post #18 showed readings from two PMs which, on average, differed by 3-4%. This is why I've been saying that knowing that two devices are close on average isn't that important: average closeness is a pretty low bar. What's important is knowing when they're different, by how much, and what effect that has on what you're trying to do. Training doesn't make a lot of demands on data fidelity but training isn't the only thing one can do with power data.

Last edited by RChung; 10-23-21 at 12:01 AM.
RChung is offline  
Old 10-23-21, 07:01 AM
  #37  
PeteHski
Senior Member
 
PeteHski's Avatar
 
Join Date: May 2021
Posts: 2,165
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 1073 Post(s)
Liked 1,126 Times in 713 Posts
Originally Posted by RChung View Post
Coincidentally, that plot in post #18 showed readings from two PMs which, on average, differed by 3-4%. This is why I've been saying that knowing that two devices are close on average isn't that important: average closeness is a pretty low bar. What's important is knowing when they're different, by how much, and what effect that has on what you're trying to do. Training doesn't make a lot of demands on data fidelity but training isn't the only thing one can do with power data.
Sure, that's why I check them at power levels I'm actually interested in. But they agree on average across a whole ride too. So I have no reason to believe there is an issue between my 2 PMs. I dual record quite often and don't see any anomalies across my useful power range. I will have a 3rd PM soon to cross-reference. As you say training is not very demanding on data fidelity, although consistency is still very important. It would be no good if it was inconsistent around my threshold power range, but I'm not bothered about accuracy sub 100W or >600W. My crank PM tends to show higher peaks than my trainer in sprints, but I'm not that surprised given the damping through the drivetrain. But averaged over 5 or 10 secs they agree quite closely. Sprinting is not important for the events I train for either.
PeteHski is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.