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

Advice on Power Meter

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

Advice on Power Meter

Old 05-19-20, 09:34 PM
  #26  
tomato coupe
Senior Member
 
Join Date: Jul 2009
Posts: 1,214

Bikes: Colnago, Van Dessel, Factor, Cervelo, Ritchey

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 734 Post(s)
Liked 701 Times in 311 Posts
Originally Posted by Seattle Forrest View Post
That's kind of disturbing.
Yes, but only mildly.
tomato coupe is offline  
Old 05-19-20, 10:49 PM
  #27  
NoWhammies
Senior Member
 
NoWhammies's Avatar
 
Join Date: Jul 2017
Location: Vancouver, BC
Posts: 1,402

Bikes: Argon 18 Gallium, BH G7, Rocky Mountain Instinct C70

Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 605 Post(s)
Liked 207 Times in 130 Posts
My recommendation is for a left sided PM from 4iiii. I've had mine on my bike for over a year now. No complaints. I get over 120 hours from the battery, so while I considered the rechargeable 4iiii unit, I settled on the left side arm requiring the CR2032 battery.
NoWhammies is offline  
Old 05-20-20, 06:52 AM
  #28  
RChung
Senior Member
 
Join Date: Sep 2009
Posts: 1,625
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 385 Post(s)
Liked 221 Times in 91 Posts
Originally Posted by tomato coupe View Post
I used to worry about L/R imbalance, but now choose to ignore it. Why? Two of my four power meters provide L/R imbalance; one consistently says my left side is stronger (53/47) while the other says my right side is stronger (46/54). (The overall power for all four meters is within 1-2%.)
That's interesting. Are these two the same model/brands, or different? What models/brands are they?

Some crank spider PMs (like, P2M and Quarq) produce L/R splits but they can be flaky because of the way they try to calculate the split. That said, some crank arm PMs produce kinda flaky data, too. I've wondered about pedal PMs but haven't had a chance to do a full test on their splits.
RChung is offline  
Old 05-20-20, 10:40 AM
  #29  
tomato coupe
Senior Member
 
Join Date: Jul 2009
Posts: 1,214

Bikes: Colnago, Van Dessel, Factor, Cervelo, Ritchey

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 734 Post(s)
Liked 701 Times in 311 Posts
Originally Posted by RChung View Post
That's interesting. Are these two the same model/brands, or different? What models/brands are they?

Some crank spider PMs (like, P2M and Quarq) produce L/R splits but they can be flaky because of the way they try to calculate the split. That said, some crank arm PMs produce kinda flaky data, too. I've wondered about pedal PMs but haven't had a chance to do a full test on their splits.
The meters in disagreement are a P2M and Garmin Vector 3. Technologically, I have more faith in the Vectors for L/R splits, however, the P2M L/R splits align better with known physiological differences, i.e. leg size and injuries. I could throw a couple other meters into the mix to shed some light (murk?) on the subject, but the discrepancy doesn't affect what I'm doing so it's easy to ignore.
tomato coupe is offline  
Old 05-20-20, 10:59 AM
  #30  
guadzilla
Pointy Helmet Tribe
 
guadzilla's Avatar
 
Join Date: Feb 2009
Location: Offthebackistan
Posts: 4,179

Bikes: Venge, R5, Shiv, Lynskey and a few more

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 426 Post(s)
Liked 514 Times in 241 Posts
Originally Posted by tomato coupe View Post
I used to worry about L/R imbalance, but now choose to ignore it. Why? Two of my four power meters provide L/R imbalance; one consistently says my left side is stronger (53/47) while the other says my right side is stronger (46/54). (The overall power for all four meters is within 1-2%.)
If one of those is the 4iii or Stages on a Shimano crank, apparently there are documented issues with L/R balance with them.

Edit - NVM. Garmin and P2M.
guadzilla is offline  
Old 05-20-20, 03:29 PM
  #31  
RChung
Senior Member
 
Join Date: Sep 2009
Posts: 1,625
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 385 Post(s)
Liked 221 Times in 91 Posts
Originally Posted by tomato coupe View Post
The meters in disagreement are a P2M and Garmin Vector 3. Technologically, I have more faith in the Vectors for L/R splits, however, the P2M L/R splits align better with known physiological differences, i.e. leg size and injuries. I could throw a couple other meters into the mix to shed some light (murk?) on the subject, but the discrepancy doesn't affect what I'm doing so it's easy to ignore.
Thanks. The P2M and Quarq impute L/R split but don't actually observe it directly. But from a functional standpoint, I agree with you -- what matters is total power, and you seem to be pretty consistent across all four of your PMs with that.
RChung is offline  
Likes For RChung:
Old 05-20-20, 04:25 PM
  #32  
tomato coupe
Senior Member
 
Join Date: Jul 2009
Posts: 1,214

Bikes: Colnago, Van Dessel, Factor, Cervelo, Ritchey

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 734 Post(s)
Liked 701 Times in 311 Posts
Originally Posted by RChung View Post
Thanks. The P2M and Quarq impute L/R split but don't actually observe it directly.
Yeah, the P2M definitely gets fooled by any "pulling up" on the pedals. For instance, it's almost impossible to get a 100/0 L/R split with the P2M when doing a one legged drill, whereas it's almost impossible not to get a 100/0 split with the Vectors.
tomato coupe is offline  
Old 05-20-20, 07:13 PM
  #33  
RChung
Senior Member
 
Join Date: Sep 2009
Posts: 1,625
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 385 Post(s)
Liked 221 Times in 91 Posts
One-legged drills make a lot of sense if you have only one leg.

The overall rule is one should pedal with as many legs as one has.
RChung is offline  
Likes For RChung:
Old 05-20-20, 07:14 PM
  #34  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 30,658

Bikes: R3 Disc, Haanjo

Mentioned: 338 Post(s)
Tagged: 1 Thread(s)
Quoted: 13603 Post(s)
Liked 2,875 Times in 1,540 Posts
Originally Posted by RChung View Post
One-legged drills make a lot of sense if you have only one leg.

The overall rule is one should pedal with as many legs as one has.
WhyFi is online now  
Old 05-20-20, 10:39 PM
  #35  
tomato coupe
Senior Member
 
Join Date: Jul 2009
Posts: 1,214

Bikes: Colnago, Van Dessel, Factor, Cervelo, Ritchey

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 734 Post(s)
Liked 701 Times in 311 Posts
Originally Posted by RChung View Post
One-legged drills make a lot of sense if you have only one leg.

The overall rule is one should pedal with as many legs as one has.
We've had a bear, a bobcat, two moose, a bunch of coyotes, and a beagle-corgi mix in our yard in the past few months – I want to be prepared in case I have to pedal with one leg.
tomato coupe is offline  
Old 05-21-20, 04:59 AM
  #36  
Jazzguitar
Senior Member
 
Join Date: Mar 2016
Location: Boston
Posts: 129
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 49 Post(s)
Liked 2 Times in 2 Posts
Originally Posted by DrIsotope View Post
I learned rather quickly that dual-sided means next to nothing to me. If I'm over 70% intensity, it's 50/50. If I'm under 70%, it's 51/49.
Same for me, most rides finish at 50/50 or 51/49. At low intensity I have a slight imbalance, usually a few percent, but it evens out as I approach threshold. I’ve had dual sided Garmin Vectors for about 4 years so when it was time to pick up a PM for my gravel bike I opted for a single side crank arm since I knew dual sided wasn’t going to add anything except cost.

Last edited by Jazzguitar; 05-21-20 at 05:56 AM.
Jazzguitar is offline  
Old 05-21-20, 05:10 AM
  #37  
ZHVelo
Senior Member
 
Join Date: Apr 2020
Location: Zurich, Switzerland
Posts: 419
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 253 Post(s)
Liked 123 Times in 84 Posts
I have been using Assioma Duo for over a month now. Works amazing.

I would echo what others said though - dual probably does not add much value, the sides are almost always with the 50-50 to 51-49 range.
ZHVelo is online now  
Old 05-21-20, 06:59 AM
  #38  
Froomewannabe
Senior Member
 
Join Date: Aug 2017
Posts: 58
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Liked 5 Times in 4 Posts
I got my 105 4i left only power meter in the mail yesterday. Hope it will fit and get it installed for an outside ride by the week-end.

I decided at my level this will work fine at $300. I am using Trainerroad and plan to get a Garmin or Wahoo that I can push some of the workouts outside, so I effectively will have spent about the same, but have the workable package. If I feel like improve pass this level and need dual sided, I will put it on ebay.
Froomewannabe is offline  
Old 05-21-20, 07:16 AM
  #39  
Duganator9
Junior Member
 
Join Date: May 2020
Posts: 18
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 6 Times in 4 Posts
A lot of people hate on the single sided power meters, but I absolutely love my 4iiii power meter. It's been Rock solid since I bought it, only changed the battery one time.
Duganator9 is offline  
Likes For Duganator9:
Old 05-21-20, 08:18 AM
  #40  
jad3675
Senior Member
 
Join Date: Aug 2016
Posts: 65
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
Likes: 0
Liked 4 Times in 3 Posts
I'll give a non-recommendation to Avio Power Meter. Great idea (self install crank PM), but terrible execution. Units have been out for over 18 months, and they still can't address a phantom battery drain issue. Well, they say they have with the latest firmware, but that firmware doesn't calibrate properly - you end up putting out 2000 watts. I had a unit installed for 6 months - the battery issue got so bad I was replacing the battery every other day. Last week the unit stopped working even with a new battery - icing on that cake was the battery door broke from repeated removal/install. So, I took a mallet and plastic prybar and removed the POS.

I think I'll be going with pedal based system.

John
jad3675 is offline  
Old 05-23-20, 09:14 AM
  #41  
RChung
Senior Member
 
Join Date: Sep 2009
Posts: 1,625
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 385 Post(s)
Liked 221 Times in 91 Posts
Originally Posted by tomato coupe View Post
We've had a bear, a bobcat, two moose, a bunch of coyotes, and a beagle-corgi mix in our yard in the past few months – I want to be prepared in case I have to pedal with one leg.
You wouldn't need to prepare to pedal with one leg if you always go into your yard with someone slower.
RChung is offline  
Likes For RChung:
Old 05-23-20, 09:56 AM
  #42  
tomato coupe
Senior Member
 
Join Date: Jul 2009
Posts: 1,214

Bikes: Colnago, Van Dessel, Factor, Cervelo, Ritchey

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 734 Post(s)
Liked 701 Times in 311 Posts
Originally Posted by RChung View Post
You wouldn't need to prepare to pedal with one leg if you always go into your yard with someone slower.
Yes, but I'm running out of volunteers...

Our bobcat was back yesterday. He's pretty smart – he can spot a steel frame and goes after those riders first.

tomato coupe is offline  
Old 05-23-20, 12:38 PM
  #43  
ridethecliche
Village Idiot
 
Join Date: Jan 2007
Location: Dirty Jerz
Posts: 20,484
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 96 Post(s)
Liked 91 Times in 66 Posts
I would get a used stages or 4iiii.

When it comes to training and measurement, consistency is key. If you favor your right or your left leg, how are you going to train differently based on that? If you go to the gym, you should be doing the same number of reps/sets with both legs and that's about all you can do. Sure you can do 1 leg drills on the bike, but are you really going to do them for one leg only?

Consistency is key.
If your left leg is stronger or weaker... it doesn't matter. The PM is measuring the same thing every time. You'll see improvement there as it comes. Unless there's a reason for you to suspect that your legs might be getting stronger at different rates then I wouldn't worry about it.

I used to have an SRM. Very happy with my current 1 sided PM. I no longer race and I've been getting back into things and it's a fantastic way, esp to start off. If you buy used you can resell without much of a loss. I'd do it the same way again if I had to! Easy to swap between my two bikes as well. Takes like 5 mins.
ridethecliche is offline  
Likes For ridethecliche:
Old 05-24-20, 09:08 AM
  #44  
PoorInRichfield
Senior Member
 
Join Date: Nov 2013
Location: Richfield, WI
Posts: 464

Bikes: Trek Domane SL7 Disc, Trek Boone 9, Cannondale F29

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 247 Post(s)
Liked 179 Times in 109 Posts
Originally Posted by ridethecliche View Post
Consistency is key.
My view on power meters changed radically after trying to buy a stupid bathroom scale. I weigh myself daily and wanted "the most accurate scale". After much research, I found that the search for an accurate scale was largely meaningless. I could buy 30 scales and I'd be willing to bet that all 30 scales would give me slightly different readings on any given day. Even if 15 of them gave consistent weight readings, how do I know that those 15 are "accurate" and not just equally wrong? Will the scale readings change over time as parts wear? Does it even matter what number my scale reads in comparison to anyone else's? If my scale says I weigh 165 lbs but a finely calibrated, high precise, gazillion dollar scale used for measuring gold (?) says I actually weigh 164.354 lbs, does that really matter?

As RideTheCliche states, I think what is actually important is if the meter you bought is consistent with itself over time. It's only through this consistency that you can determine if your fitness level is improving. Of course, build quality should matter as well but is quality is usually assumed no matter which power meter is purchased. (I.e., if the power meter doesn't work half the time, it's of no value no matter how "accurate" it is.)

If I was the chief mechanic for a large cycling team, that might be another story. In which case, I would think it is important that all the rider's power meters are calibrated consistently so comparisons between riders could be made.

Originally Posted by tomato coupe View Post
Our bobcat was back yesterday. He's pretty smart – he can spot a steel frame and goes after those riders first.
And here I thought being chased by an occasional dog was scary
PoorInRichfield is offline  
Likes For PoorInRichfield:
Old 05-24-20, 10:15 AM
  #45  
RChung
Senior Member
 
Join Date: Sep 2009
Posts: 1,625
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 385 Post(s)
Liked 221 Times in 91 Posts
Originally Posted by PoorInRichfield View Post
As RideTheCliche states, I think what is actually important is if the meter you bought is consistent with itself over time. It's only through this consistency that you can determine if your fitness level is improving.
Sigh.

1. It's possible to check the accuracy of a bathroom scale.
2. Whether consistency is all you need depends on what you're doing with the information.
3. My step dad was a butcher so I used to work in the shop. I can guarantee that if the scales in the shop were consistent but inaccurate, we would have been in a lot of trouble.
4. Whether consistency is all you need depends on what you're doing with the information.
RChung is offline  
Likes For RChung:
Old 05-24-20, 12:31 PM
  #46  
phrantic09
Road Newb
 
Join Date: Oct 2013
Location: Saratoga, NY
Posts: 740

Bikes: Felt Z4, Felt F75, Cervelo R3

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 510 Post(s)
Liked 353 Times in 148 Posts
I personally wouldn’t buy any crankarm based dual sided PM for current gen Shimano cranks. I had a Stages on backorder until I read the info gplama posted about the right side being inaccurate, after that, I went for pedal based PM instead. Really happy with my Vector 3.

https://gplama.com/2019/06/29/shiman...-power-meters/
phrantic09 is offline  
Old 05-24-20, 09:36 PM
  #47  
Seattle Forrest
Senior Member
 
Seattle Forrest's Avatar
 
Join Date: Mar 2010
Location: Seattle, WA
Posts: 21,389
Mentioned: 68 Post(s)
Tagged: 0 Thread(s)
Quoted: 12456 Post(s)
Liked 3,827 Times in 2,139 Posts
Originally Posted by RChung View Post
Sigh.

1. It's possible to check the accuracy of a bathroom scale.
2. Whether consistency is all you need depends on what you're doing with the information.
3. My step dad was a butcher so I used to work in the shop. I can guarantee that if the scales in the shop were consistent but inaccurate, we would have been in a lot of trouble.
4. Whether consistency is all you need depends on what you're doing with the information.
They really cost too much to give consistent but inaccurate data, anyway.
Seattle Forrest is offline  
Old 05-25-20, 06:45 PM
  #48  
ridethecliche
Village Idiot
 
Join Date: Jan 2007
Location: Dirty Jerz
Posts: 20,484
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 96 Post(s)
Liked 91 Times in 66 Posts
Originally Posted by RChung View Post
Sigh.

1. It's possible to check the accuracy of a bathroom scale.
2. Whether consistency is all you need depends on what you're doing with the information.
3. My step dad was a butcher so I used to work in the shop. I can guarantee that if the scales in the shop were consistent but inaccurate, we would have been in a lot of trouble.
4. Whether consistency is all you need depends on what you're doing with the information.
Which is something that I mentioned in my post above the poster whom you responded to. Weighing in for an event with weight classing (think boxing or mma) is very different than tracking changes to your weight. Using a PM to track performance improvement and fitness as well as estimate calories consumed by a rec rider/amateur racer is very different than using it to tailor leg workouts to even out discrepancy in a track sprinter.

The vast majority of folks buying these devices will likely never use them in ways where what one is doing with that information truly benefits from the additional info. Hell, if all you're doing is posting your numbers on strava then it doesn't even matter does it? Wait, in that case you'll want something that reads high and can have the offset modified to read even higher!

These discussions are often fun to have though. It's pretty cool to see how far things have come since 10+ years ago when I used to have a wired SRM.

Oh! I can say that 1 sided crank based PM's will make your one leg drills look rather hilarious during a log though!

Originally Posted by Seattle Forrest View Post
They really cost too much to give consistent but inaccurate data, anyway.
This concern for 'inaccuracy' is largely unfounded if you're buying a vetted unit though. Looking at DCR or GPL before buying an item can help one see how they stack up to other accepted units and allow a buyer to see how they do when it comes to both internal consistency and 'accuracy'. With that info in mind, and a +/- 1-2% difference in internal consistency... what else do you really need for the riders mentioned above?
ridethecliche is offline  
Old 05-25-20, 07:18 PM
  #49  
colnago62
Senior Member
 
Join Date: Aug 2014
Posts: 2,044
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 557 Post(s)
Liked 229 Times in 135 Posts
Originally Posted by ridethecliche View Post
Using a PM to track performance improvement and fitness as well as estimate calories consumed by a rec rider/amateur racer is very different than using it to tailor leg workouts to even out discrepancy in a track sprinter.
I have never heard or talked to a sprinter who used a powermeter to even out leg strength. My guess would be that they spend so much time in the gym that an issue like that would dealt with there. What is cool is how sprinters and their coaches use power to determine what their optimum gear will be for a particular track or situation. A good gear not only gives quick acceleration, but also slower deceleration.
colnago62 is offline  
Likes For colnago62:
Old 05-25-20, 08:18 PM
  #50  
RChung
Senior Member
 
Join Date: Sep 2009
Posts: 1,625
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 385 Post(s)
Liked 221 Times in 91 Posts
Originally Posted by ridethecliche View Post
The vast majority of folks buying these devices will likely never use them in ways where what one is doing with that information truly benefits from the additional info.
Oh, I think I've said that too, since I think the majority of riders use their power meters in pretty simple ways. That said, some don't, and we can't know ahead of time who is going to be in which camp. It's better to say that whether you need more than consistent inaccuracy depends on what you're going to do with the data than it is to declare that no one ever needs anything more than that.

This concern for 'inaccuracy' is largely unfounded if you're buying a vetted unit though. Looking at DCR or GPL before buying an item can help one see how they stack up to other accepted units and allow a buyer to see how they do when it comes to both internal consistency and 'accuracy'.
Actually, I know Ray Maker. He's consulted with me (and occasionally still does) on especially complicated power meter issues. I helped him set up his test protocols. And, although I've never met Shane in person, if you look up his observations on dual-sided Stages PMs you'll see what he thinks of their accuracy.
RChung is offline  
Likes For RChung:

Thread Tools
Search this Thread

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

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.