mecheng89 Posted January 25 Posted January 25 (edited) 16 hours ago, ianct said: Bought a new Ultegra 4iiii power meter and took a first ride today. Paired fine with a Garmin 530 and did the calibration (and again mid-ride because I thought something was wrong). On a gentle hill, seated in a Zone 2-3 heart rate effort, keeping the pedalling as smooth as I can, the power is fluctuating wildly over about 5sec from around 270W-160W - jumping up and down 20-30W at a time. I'm keeping the pedalling pretty consistent and the bike is smooth and stable and going at the same speed - there is no way the power is fluctuating anything like that much. Checked in with 4iiii and they sent me a link to a tech document saying the unit supplies raw power data and I must implement 3, 5 or 10 sec smoothing at the head unit. Does this sound right? Anyone have experience with this? I'm new to the power meter game so trying to work out if I have a faulty unit or this is normal? Yes, it sounds correct. Your PM is fine. Smoothing the recording is better. If it read zero or very high, then I'd be worried. Don't fret too much. Focus on learning about your body, how the effort feels. If you go analyse your data afterwards, you get to know what Z2, 3, 4, 7 "feels" like aka RPE. I love the numbers, but lately I haven't really cared. The power number is a consequence of your effort. IMHO, if you want to train to power, doing it outside will just wreck your brain. The smart trainer, even though lots of people dislike it, has been proven over and over to be a better use of your time. Edited January 25 by mecheng89 Spelling cadenceblur 1
ianct Posted January 26 Author Posted January 26 In response to a number of people... the power meter was really unusable without smoothing - it would start at around 250W then jump up in 20-30W increments to around 270 or 280, then dive down to around 150/160 over a few seconds, then jump up again. There is no way I was putting out 100+ watts of variance in power over about 5 seconds of seated peddling on a consistent gradient. The good news is the 3sec mode improved matters a lot, to the point that it makes sense and is a readable number. My guess at what is happening is that the left side only PM reads through the stroke - obviously when pushing down you make power and then through the dead zone and on the upstroke there is much less power. Then it sends a signal over ANT+ or BT to the head unit but there is a transmission interval between when each packet of data is sent, and then an interval between each loop when the head unit reads the data, and then an interval when the head unit updates the display of the number. If that gets out of sync with the power meter, then it is sometimes displaying the amount from the upstroke, and other times the downstroke, and others the dead point, then that would explain this wild jumping. Anyway, 3 sec smoothing sorts most of this out and I'm sure 10 sec will do that even more. Out of interest it's the latest Precision 3 and on latest firmware and calibrated several times. Cheers for all the advice and comments. Donovan Le Cok 1
Rudi Pollard Posted January 26 Posted January 26 42 minutes ago, ianct said: In response to a number of people... the power meter was really unusable without smoothing - it would start at around 250W then jump up in 20-30W increments to around 270 or 280, then dive down to around 150/160 over a few seconds, then jump up again. There is no way I was putting out 100+ watts of variance in power over about 5 seconds of seated peddling on a consistent gradient. The good news is the 3sec mode improved matters a lot, to the point that it makes sense and is a readable number. My guess at what is happening is that the left side only PM reads through the stroke - obviously when pushing down you make power and then through the dead zone and on the upstroke there is much less power. Then it sends a signal over ANT+ or BT to the head unit but there is a transmission interval between when each packet of data is sent, and then an interval between each loop when the head unit reads the data, and then an interval when the head unit updates the display of the number. If that gets out of sync with the power meter, then it is sometimes displaying the amount from the upstroke, and other times the downstroke, and others the dead point, then that would explain this wild jumping. Anyway, 3 sec smoothing sorts most of this out and I'm sure 10 sec will do that even more. Out of interest it's the latest Precision 3 and on latest firmware and calibrated several times. Cheers for all the advice and comments. You'll be very surprised how difficult it is to hold a consistent number even on a 3sec averaging number. Power numbers fluctuate a lot with very small increases or decreases in the gradient you are riding. It get's easier to hold a number the more used to training with it you get. Happy power intervals!!! DieselnDust 1
ianct Posted January 26 Author Posted January 26 1 minute ago, Rudi Pollard said: You'll be very surprised how difficult it is to hold a consistent number even on a 3sec averaging number. Power numbers fluctuate a lot with very small increases or decreases in the gradient you are riding. It get's easier to hold a number the more used to training with it you get. Happy power intervals!!! Yeah saw that, but it's within reason. Without smoothing it was just gibberish and completely useless.
Spinnekop Posted January 26 Posted January 26 (edited) 28 minutes ago, ianct said: Yeah saw that, but it's within reason. Without smoothing it was just gibberish and completely useless. 31 minutes ago, Rudi Pollard said: You'll be very surprised how difficult it is to hold a consistent number even on a 3sec averaging number. Power numbers fluctuate a lot with very small increases or decreases in the gradient you are riding. It get's easier to hold a number the more used to training with it you get. Happy power intervals!!! Trick is. Set up a "lap avg power" field on the device. Start a lap and work towards your goal avg watt by working with just that field. Edited January 26 by Spinnekop Frosty 1
Frosty Posted January 26 Posted January 26 Just post a screenshot of one of your data files, showing a section of steady riding. Many users here will be able to, quickly, tell you if it's a problem or not. Spinnekop 1
DieselnDust Posted January 26 Posted January 26 On 1/24/2024 at 7:07 PM, ianct said: Bought a new Ultegra 4iiii power meter and took a first ride today. Paired fine with a Garmin 530 and did the calibration (and again mid-ride because I thought something was wrong). On a gentle hill, seated in a Zone 2-3 heart rate effort, keeping the pedalling as smooth as I can, the power is fluctuating wildly over about 5sec from around 270W-160W - jumping up and down 20-30W at a time. I'm keeping the pedalling pretty consistent and the bike is smooth and stable and going at the same speed - there is no way the power is fluctuating anything like that much. Checked in with 4iiii and they sent me a link to a tech document saying the unit supplies raw power data and I must implement 3, 5 or 10 sec smoothing at the head unit. Does this sound right? Anyone have experience with this? I'm new to the power meter game so trying to work out if I have a faulty unit or this is normal? Sounds absolutely spot on! what were you expecting? This is how power meters deliver data without averaging Rudi Pollard 1
cadenceblur Posted January 26 Posted January 26 OP perhaps also do some research around how to get the most out of your PM otherwise you’ll just have an expensive crank arm. FTP as a start, then set up your zones etc etc. it’s a great tool if used properly Rudi Pollard 1
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