WTD: Someone with Power Meter to help calibrate my trainer

2

Comments

  • Alex_Simmons/RST
    Alex_Simmons/RST Posts: 4,161
    ziglar wrote:
    Got a cheap Powertap off ebay. No doubt it will give a completely different set of readings and as pointed out I will still have no idea which is more correct as it too may be horribly calibrated ... C'est la vie.
    Except that it is possible to verify the calibration of your Powertap. It's a measurable thing.
    RST Sport : Coaching - Training Plans - Powermeters -- My blog -- AeroCoach Australia
  • amaferanga
    amaferanga Posts: 6,789
    ziglar wrote:
    Got a cheap Powertap off ebay. No doubt it will give a completely different set of readings and as pointed out I will still have no idea which is more correct as it too may be horribly calibrated ... C'est la vie.

    Calibration check with a Garmin.
    More problems but still living....
  • ziglar
    ziglar Posts: 112
    Funnily enough the Garmin Calibration page was the last thing I found last night whilst looking for info.

    I will give this a go this evening and hope that the LYC will do the same job as the Garmin for this procedure.
  • Alex_Simmons/RST
    Alex_Simmons/RST Posts: 4,161
    The LYC is better for the purpose IMO.
    RST Sport : Coaching - Training Plans - Powermeters -- My blog -- AeroCoach Australia
  • Trev The Rev
    Trev The Rev Posts: 1,040
    You could try the well tested 'Effort Meter' which reliably senses the effort made by leg muscles, and cardiovascular system. The device also advises when cooling is required, when to hydrate and eat. The system does not measure power in watts though - only effort, 300 watts when fresh & rested being less effort than 300 watts when very tired from the previous days training, or 300 watts being more effort in hot humid conditions than in mild conditions etc etc. 300 watts needing more effort for some riders than others. Threshold 'effort' being easy to judge no matter what the terrain or conditions, it also comes with automatic pacing for training & racing. Sad that these days few people remember how to use this simple reliable system.
  • StorckSpeed
    StorckSpeed Posts: 291
    Trev The Rev wrote:
    moonshine wrote:
    I did a "test" on a club mates Tacx flow using my (trev) calibrated PT SL+.
    The outcome was the Flow over read by up to 30% for any given wattage, reporting approx 400w power for a 300wPT effort.
    We also had doubts about drift in the session & session reproducibility for the reasons outlined by Alex.
    In short, we came to the conclusion the Flow was virtually useless as a serious training tool and was more of a gimmick.
    My club mate is looking at buying a "proper" PM now instead.

    If you set the pressure of the roller on the tyre to the maximum you get more realistic power readings (I did on mine anyway) but the Tacx Flow does not give realistic power figures. It is reasonably repeatable though if you always set the roller to tyre and tyre pressure the same.

    I've done the same thing and found around a 10% over read. So if your effort is 300W the reading will be 330W. When you calibrate the brake at the end of your warm up session this is repeatable. So ultimately you can then use the flow to view your power output and to test your output, keeping the 10% over-read in mind.
    Every Power Meter has a % tolerance, this will be stated by the manufacturer and none of them will claim 100% accuracy. So ultimately in the test above my wheel could be 5% off and the flow trainer could be 5% off adding up to a 10% difference.
    I've also compared Power Readings with other club mates whilst riding alongside them and have always found a % difference so I don't see the difference. Ultimately even a calibrated wheel is only accurate at the moment the calibration was done, any bash, thump, movement after this can affect calibration. Yes you can self calibrate but whose to say this is 100% accurate unless you do comparisons alongside a calibration device each time you'll never know......
    From the other posts - Even a brand new Garmin may not do the calibration correctly, this too will have a tolerance, but you will be able to repeat the process fairly accurately.
    There's warp speed - then there's Storck Speed
  • Trev The Rev
    Trev The Rev Posts: 1,040
    [
    What, power meters not accurate and need calibrating, you will be saying there are fairies at the bottom of the garden next. All that power meter data analysis might be wrong because the power meter might not necessarily be calibrated correctly, good god man, this could lead people to need counselling.
  • amaferanga
    amaferanga Posts: 6,789
    StorckSpeed wrote:
    Every Power Meter has a % tolerance, this will be stated by the manufacturer and none of them will claim 100% accuracy. So ultimately in the test above my wheel could be 5% off and the flow trainer could be 5% off adding up to a 10% difference.

    If your power meter is out by 5% then you should send it back for service and/or calibration.
    More problems but still living....
  • Alex_Simmons/RST
    Alex_Simmons/RST Posts: 4,161
    Trev The Rev wrote:
    What, power meters not accurate and need calibrating, you will be saying there are fairies at the bottom of the garden next. All that power meter data analysis might be wrong because the power meter might not necessarily be calibrated correctly, good god man, this could lead people to need counselling.
    Are you banned from the TTF or something? :lol:
    RST Sport : Coaching - Training Plans - Powermeters -- My blog -- AeroCoach Australia
  • Trev The Rev
    Trev The Rev Posts: 1,040
    Alex_Simmons/RST wrote:
    Trev The Rev wrote:
    What, power meters not accurate and need calibrating, you will be saying there are fairies at the bottom of the garden next. All that power meter data analysis might be wrong because the power meter might not necessarily be calibrated correctly, good god man, this could lead people to need counselling.
    Are you banned from the TTF or something? :lol:

    Yes, partly due to complaints by people trying to sell power meters, they get a bit touchy whenever I point out how many threads there are on timetrialling forum about power meters that don't work properly.
  • amaferanga
    amaferanga Posts: 6,789
    Trev The Rev wrote:
    Alex_Simmons/RST wrote:
    Trev The Rev wrote:
    What, power meters not accurate and need calibrating, you will be saying there are fairies at the bottom of the garden next. All that power meter data analysis might be wrong because the power meter might not necessarily be calibrated correctly, good god man, this could lead people to need counselling.
    Are you banned from the TTF or something? :lol:

    Yes, partly by people trying to sell power meters, they get a bit touchy whenever I point out how many threads there are on timetrialling forum about power meters that don't work properly.

    So the reason you're banned is all their fault and not yours? You're entirely innocent, did nothing wrong right?
    More problems but still living....
  • Trev The Rev
    Trev The Rev Posts: 1,040
    amaferanga wrote:
    Trev The Rev wrote:
    Alex_Simmons/RST wrote:
    Trev The Rev wrote:
    What, power meters not accurate and need calibrating, you will be saying there are fairies at the bottom of the garden next. All that power meter data analysis might be wrong because the power meter might not necessarily be calibrated correctly, good god man, this could lead people to need counselling.
    Are you banned from the TTF or something? :lol:

    Yes, partly by people trying to sell power meters, they get a bit touchy whenever I point out how many threads there are on timetrialling forum about power meters that don't work properly.

    So the reason you're banned is all their fault and not yours? You're entirely innocent, did nothing wrong right?


    What has Molteni Mike's little tantrum on timetrialling forum got to do with the reliability of power meters?

    Things follow a familiar pattern, people don't like what I say so instead of reasoned argument they attack me personally. You don't like the fact that I am pointing out that power meters are unreliable so you want to talk about why I was banned from time trialling forum - interesting.
  • amaferanga
    amaferanga Posts: 6,789
    Trev The Rev wrote:
    amaferanga wrote:
    Trev The Rev wrote:
    Alex_Simmons/RST wrote:
    Trev The Rev wrote:
    What, power meters not accurate and need calibrating, you will be saying there are fairies at the bottom of the garden next. All that power meter data analysis might be wrong because the power meter might not necessarily be calibrated correctly, good god man, this could lead people to need counselling.
    Are you banned from the TTF or something? :lol:

    Yes, partly by people trying to sell power meters, they get a bit touchy whenever I point out how many threads there are on timetrialling forum about power meters that don't work properly.

    So the reason you're banned is all their fault and not yours? You're entirely innocent, did nothing wrong right?


    What has Molteni Mike's little tantrum on timetrialling forum got to do with the reliability of power meters?

    Things follow a familiar pattern, people don't like what I say so instead of reasoned argument they attack me personally. You don't like the fact that I am pointing out that power meters are unreliable so you want to talk about why I was banned from time trialling forum - interesting.

    I have absolutely no idea what went on with the TT forum and you and to be honest I don't really care.

    And I have no desire to discuss you so let's just get back on topic.
    More problems but still living....
  • Trev The Rev
    Trev The Rev Posts: 1,040
    In my opinion, power meters being so unreliable and expensive, people should seriously consider if they are worth the trouble. I doubt there is much point in trying to calibrate a turbo using a power meter. The effort would be better spent making sure any results on the turbo are repeatable by making sure tyre pressure and pressure of roller on the tyre is the same for each session.
  • t.m.h.n.e.t
    t.m.h.n.e.t Posts: 2,265
    That's great Trev, but can you stop shitting on every thread that mentions some form of technology you don't like??
  • Team4Luke
    Team4Luke Posts: 597
    Alex_Simmons/RST wrote:
    Speed on a trainer is meaningless. All that matters is intensity and time.


    not neccessarily, depends on the trainer and whether you run a permanent bike and permanent conditions including being in a fixed room ie never moved and using same tyre pressures, same tyre and doing a roll down, same resistance setting, I never change mine resistance setting just no need etc, I would agree that sticking your bike on/off every time would lead to variables but not a fixed rig set up and if you have that then no reason you can not simply say ride at 20mph for an hour (not using turbo speed though) and of course that in itself is an intensity, progression from that would be holding out for 21mph an hour etc.
    Doesn't take much to set up a fixed rig, you only need bare minimum of a whole bike, second hand bits, proper turbo tyre and should be no need to move it ever and should get easily a year out of a tyre if not more.
    Team4Luke supports Cardiac Risk in the Young
  • Trev The Rev
    Trev The Rev Posts: 1,040
    T.M.H.N.E.T wrote:
    That's great Trev, but can you stop ******** on every thread that mentions some form of technology you don't like??


    Just as people can come on a forum and state how much they like and explain the benefits of a particular technology, I think I am allowed to point out any draw backs a particular technology may have. Given people might part with hard earned cash, or credit extended at userious interest rates, I think it reasonable people are infomed of the cons as well as the pros.
  • t.m.h.n.e.t
    t.m.h.n.e.t Posts: 2,265
    Trev The Rev wrote:
    T.M.H.N.E.T wrote:
    That's great Trev, but can you stop ******** on every thread that mentions some form of technology you don't like??


    Just as people can come on a forum and state how much they like and explain the benefits of a particular technology, I think I am allowed to point out any draw backs a particular technology may have. Given people might part with hard earned cash, or credit extended at userious interest rates, I think it reasonable people are infomed of the cons as well as the pros.
    It's also reasonable that the people with money to spend on technology have some clue as to how it works and what it does.

    There is a huge difference in pointing things out and whining like a little bitch. You stopped doing the former many many posts ago.
  • Trev The Rev
    Trev The Rev Posts: 1,040
    T.M.H.N.E.T wrote:
    Trev The Rev wrote:
    T.M.H.N.E.T wrote:
    That's great Trev, but can you stop ******** on every thread that mentions some form of technology you don't like??


    Just as people can come on a forum and state how much they like and explain the benefits of a particular technology, I think I am allowed to point out any draw backs a particular technology may have. Given people might part with hard earned cash, or credit extended at userious interest rates, I think it reasonable people are infomed of the cons as well as the pros.
    It's also reasonable that the people with money to spend on technology have some clue as to how it works and what it does.
    There is a huge difference in pointing things out and whining like a little *****. You stopped doing the former many many posts ago.

    Or what it is supposed to do but does not most of the time.
  • t.m.h.n.e.t
    t.m.h.n.e.t Posts: 2,265
    Trev The Rev wrote:
    T.M.H.N.E.T wrote:
    Trev The Rev wrote:
    T.M.H.N.E.T wrote:
    That's great Trev, but can you stop ******** on every thread that mentions some form of technology you don't like??


    Just as people can come on a forum and state how much they like and explain the benefits of a particular technology, I think I am allowed to point out any draw backs a particular technology may have. Given people might part with hard earned cash, or credit extended at userious interest rates, I think it reasonable people are infomed of the cons as well as the pros.
    It's also reasonable that the people with money to spend on technology have some clue as to how it works and what it does.
    There is a huge difference in pointing things out and whining like a little *****. You stopped doing the former many many posts ago.

    Or what it is supposed to do but does not most of the time.
    Do you study your toaster to make sure each slice of bread is toasted perfectly evenly? Or do you now toast on a fork over an open fire?
  • Trev The Rev
    Trev The Rev Posts: 1,040
    T.M.H.N.E.T wrote:
    Trev The Rev wrote:
    T.M.H.N.E.T wrote:
    Trev The Rev wrote:
    T.M.H.N.E.T wrote:
    That's great Trev, but can you stop ******** on every thread that mentions some form of technology you don't like??


    Just as people can come on a forum and state how much they like and explain the benefits of a particular technology, I think I am allowed to point out any draw backs a particular technology may have. Given people might part with hard earned cash, or credit extended at userious interest rates, I think it reasonable people are infomed of the cons as well as the pros.
    It's also reasonable that the people with money to spend on technology have some clue as to how it works and what it does.
    There is a huge difference in pointing things out and whining like a little *****. You stopped doing the former many many posts ago.

    Or what it is supposed to do but does not most of the time.
    Do you study your toaster to make sure each slice of bread is toasted perfectly evenly? Or do you now toast on a fork over an open fire?

    I have one of these http://www.e4electricals.com/product.aspx?id=2559 it is very reliable.
  • neeb
    neeb Posts: 4,473
    Trev The Rev wrote:
    In my opinion, power meters being so unreliable and expensive, people should seriously consider if they are worth the trouble. I doubt there is much point in trying to calibrate a turbo using a power meter. The effort would be better spent making sure any results on the turbo are repeatable by making sure tyre pressure and pressure of roller on the tyre is the same for each session.
    What do you base this on? So you are claiming that all power meters are too unreliable to consistently produce data within an acceptable margin of error (say 1- 2%) even if used properly?
  • t.m.h.n.e.t
    t.m.h.n.e.t Posts: 2,265
    Trev The Rev wrote:
    T.M.H.N.E.T wrote:
    Trev The Rev wrote:
    T.M.H.N.E.T wrote:
    Trev The Rev wrote:
    T.M.H.N.E.T wrote:
    That's great Trev, but can you stop ******** on every thread that mentions some form of technology you don't like??


    Just as people can come on a forum and state how much they like and explain the benefits of a particular technology, I think I am allowed to point out any draw backs a particular technology may have. Given people might part with hard earned cash, or credit extended at userious interest rates, I think it reasonable people are infomed of the cons as well as the pros.
    It's also reasonable that the people with money to spend on technology have some clue as to how it works and what it does.
    There is a huge difference in pointing things out and whining like a little *****. You stopped doing the former many many posts ago.

    Or what it is supposed to do but does not most of the time.
    Do you study your toaster to make sure each slice of bread is toasted perfectly evenly? Or do you now toast on a fork over an open fire?

    I have one of these http://www.e4electricals.com/product.aspx?id=2559 it is very reliable.
    How have you measured this? Wristwatch?
  • Trev The Rev
    Trev The Rev Posts: 1,040
    neeb wrote:
    Trev The Rev wrote:
    In my opinion, power meters being so unreliable and expensive, people should seriously consider if they are worth the trouble. I doubt there is much point in trying to calibrate a turbo using a power meter. The effort would be better spent making sure any results on the turbo are repeatable by making sure tyre pressure and pressure of roller on the tyre is the same for each session.
    What do you base this on? So you are claiming that all power meters are too unreliable to consistently produce data within an acceptable margin of error (say 1- 2%) even if used properly?

    I refer you to many threads on many forums where people have trouble with power meters.

    There are problems with Powertap and Quarq and SRM. My personal experience and judging from what people I have met, is that there are often calibration problems, problems with loss of signal, or erratic working.

    There are people who seem to have few problems, others have nothing but trouble.

    An example thread, http://www.timetriallingforum.co.uk/ind ... 2680&st=0&
  • ziglar
    ziglar Posts: 112
    you are obviously not advocating that people stop trying to measure their performance based on power output from powermeters so what is the alternative?
  • Trev The Rev
    Trev The Rev Posts: 1,040
    ziglar wrote:
    you are obviously not advocating that people stop trying to measure their performance based on power output from powermeters so what is the alternative?

    You do not need to measure power to train effectively. There are other ways of measuring performance. You do not need to measure performance all the time or even often.

    In an ideal world we would all have an accurate and reliable power meter, but even if we did, I don't think measuring and recording all the power meter data all the time and all the analysis is the best way for everyone.

    The big problem with measuring cycling performance is variability caused by wind, temperature & air pressure. Even accurate power measurement does not solve all problems. 300 watts on a hot humid day is harder work than 300 watts in ideal conditions. 300 watts in cold wet air might be very hard, but 300 watts on a cool dry afternoon might be easy. Air quality is a factor for many. Thus your power meter might show an improvement in watts output when the improvement is really down to better air quality or cooler conditions not improved fitness.
  • amaferanga
    amaferanga Posts: 6,789
    Trev The Rev wrote:
    neeb wrote:
    Trev The Rev wrote:
    In my opinion, power meters being so unreliable and expensive, people should seriously consider if they are worth the trouble. I doubt there is much point in trying to calibrate a turbo using a power meter. The effort would be better spent making sure any results on the turbo are repeatable by making sure tyre pressure and pressure of roller on the tyre is the same for each session.
    What do you base this on? So you are claiming that all power meters are too unreliable to consistently produce data within an acceptable margin of error (say 1- 2%) even if used properly?

    I refer you to many threads on many forums where people have trouble with power meters.

    There are problems with Powertap and Quarq and SRM. My personal experience and judging from what people I have met, is that there are often calibration problems, problems with loss of signal, or erratic working.

    There are people who seem to have few problems, others have nothing but trouble.

    An example thread, http://www.timetriallingforum.co.uk/ind ... 2680&st=0&

    Of course there are issues with power meters, like there is with any technology. People have issues with STIs for example, but it'd be ludicrous to say that because a minority of people have issues then we should all stop using them and go back to friction shifting. With power meters, provided you understand their limitations and you are at least vaguely intelligent then they are a useful training aid. Clearly they are not perfect nor are they fool proof. Some of the issues people report are user error, some are technical issues.

    Which power meters have you used then and what problems did you have exactly?
    More problems but still living....
  • amaferanga
    amaferanga Posts: 6,789
    Trev The Rev wrote:
    ziglar wrote:
    you are obviously not advocating that people stop trying to measure their performance based on power output from powermeters so what is the alternative?

    You do not need to measure power to train effectively. There are other ways of measuring performance. You do not need to measure performance all the time or even often.

    In an ideal world we would all have an accurate and reliable power meter, but even if we did, I don't think measuring and recording all the power meter data all the time and all the analysis is the best way for everyone.

    The big problem with measuring cycling performance is variability caused by wind, temperature & air pressure. Even accurate power measurement does not solve all problems. 300 watts on a hot humid day is harder work than 300 watts in ideal conditions. 300 watts in cold wet air might be very hard, but 300 watts on a cool dry afternoon might be easy. Air quality is a factor for many. Thus your power meter might show an improvement in watts output when the improvement is really down to better air quality or cooler conditions not improved fitness.

    As I said in my other post, provided you are vaguely intelligent then power meters are a useful training aid.
    More problems but still living....
  • Trev The Rev
    Trev The Rev Posts: 1,040
    amaferanga wrote:
    Trev The Rev wrote:
    neeb wrote:
    Trev The Rev wrote:
    In my opinion, power meters being so unreliable and expensive, people should seriously consider if they are worth the trouble. I doubt there is much point in trying to calibrate a turbo using a power meter. The effort would be better spent making sure any results on the turbo are repeatable by making sure tyre pressure and pressure of roller on the tyre is the same for each session.
    What do you base this on? So you are claiming that all power meters are too unreliable to consistently produce data within an acceptable margin of error (say 1- 2%) even if used properly?

    I refer you to many threads on many forums where people have trouble with power meters.

    There are problems with Powertap and Quarq and SRM. My personal experience and judging from what people I have met, is that there are often calibration problems, problems with loss of signal, or erratic working.

    There are people who seem to have few problems, others have nothing but trouble.

    An example thread, http://www.timetriallingforum.co.uk/ind ... 2680&st=0&

    Of course there are issues with power meters, like there is with any technology. People have issues with STIs for example, but it'd be ludicrous to say that because a minority of people have issues then we should all stop using them and go back to friction shifting. With power meters, provided you understand their limitations and you are at least vaguely intelligent then they are a useful training aid. Clearly they are not perfect nor are they fool proof. Some of the issues people report are user error, some are technical issues.

    Which power meters have you used then and what problems did you have exactly?

    Personally Quarq, Powertap, Garmin Vector (3 tests only), Look Keo, Wattbike. I would prefer not to talk openly on a forum about specific issues or specific brands. But I had problems. You can PM me if you want more details.
  • t.m.h.n.e.t
    t.m.h.n.e.t Posts: 2,265
    After all the preaching about innaccuracies,it's only now when directly asked for your experiences,you don't want to talk.

    Funny old world isn't it.

Categories