4iiii precision power meter, my experience

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panosk
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4iiii precision power meter, my experience

Postby panosk » Fri Oct 23, 2015 1:58 pm

After using 4iiii precision power meter the last 4 months, here is my experience

ordering/delivery procedure
Initially i was skeptical about their factory install procedure. It turned out to be a smooth procedure with 5-6 days for each trip, plus 4-5 days for installation.
The only thing you have to do is to print 6 pages and give them to the courier.
The problem some may have, is that fedex doesn't give a time window for pick up and delivery and you have to be in from 9-5.

performance
I don't know how precise it is compared with other power meters. A small test dc made, shows that it is.
I know for sure, after 4 months of use that it is consistent. Same routes, similar efforts/weather/times, similar power numbers.
The consistency is even more obvious on climbs.

battery life
This is the bad news.
With the initial firmware the batter lasted about 27 hours.
With the first firmware upgrade the battery lasted 57 hours.
They have announced a second firmware upgrade for the next few days which will increase battery life.

problems
The only problems i had with it up to now is one time that i stopped at a traffic light for about 3 minutes and when
i started pedaling again, the power displayed was enough to fly for the rest of my trip.
A second time it lost its calibration settings and had to restore the factory calibration values in order to bring power back on earth.

price
Ok, this is the cheapest power meter on the market at the moment at 400 usd, but still, i believe it is expensive.
A power meter measures just 2 metrics: torque and cadence.
You still have to pedal, so there is absolute no reason to pay more than 200 usd for a single side power meter.
...each turn of the pedals, every single meter gained, hurts...

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Re: 4iiii precision power meter, my experience

Postby march83 » Fri Oct 23, 2015 3:56 pm

re battery life, my stages doesn't do any better than 20-30hrs of riding (in fact i'd be surprised if it's actually that much!). I typically get a couple of months out of a battery and i don't ride my mtb more than once a week. I would be thrilled to get almost 60hrs.

looking forward to the double sided version, if and when it happens. then I'll be interested. my power2max tells me i have a very consistent 45/55 L/R balance so by that logic my stages constantly reads 10% low :\
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ItsDank
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Re: 4iiii precision power meter, my experience

Postby ItsDank » Fri Oct 23, 2015 4:23 pm

I'm actually considering this power meter when I get my new bike so a few questions.

1. Can you turn it off when you don't need it? Like say I'm commuting to work or doing a recovery ride, can I choose not to consume the battery and leave it off or does it automatically turn on with motion?

2. Can you turn off cadence reporting to increase battery life? I already have a Garmin Cadence sensor.

3. Is shipping to and from included in the price? If so, do they still give the option to buy a spare crank arm with it installed?

Keen to get my hands on one when my new bike arrives. Kind of a pain that I can't ride it whilst one of the cranks are headed overseas.


3.

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Drizt
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Re: 4iiii precision power meter, my experience

Postby Drizt » Fri Oct 23, 2015 4:25 pm

Once the dual sided version is available I'll buy one.

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Alex Simmons/RST
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Re: 4iiii precision power meter, my experience

Postby Alex Simmons/RST » Fri Oct 23, 2015 4:36 pm

march83 wrote:looking forward to the double sided version, if and when it happens. then I'll be interested. my power2max tells me i have a very consistent 45/55 L/R balance so by that logic my stages constantly reads 10% low :\


Unfortunately it's not that straightforward, since the power balance a P2M reports is not a true power balance. It reports the total (net) power delivered to both crank arms for each half of the crank's rotation. That's not the same as the total power supplied via each individual crank arm measured over a full rotation.

Hence you can't assume that an independent left crank arm power meter will match what a P2M power balance value suggests it might.

It's entirely possible to have perfectly accurate P2M and Garmin Vector pedals on the same bike, yet each can report a different power balance value, indeed one may report right side dominance while the other reports left side dominance. That's because they are not measuring the same thing.

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Re: 4iiii precision power meter, my experience

Postby march83 » Fri Oct 23, 2015 7:11 pm

yeah, i understand the difference completely, i was just trying to demonstrate the limitations of a single sided power measurement in an over-simplified manner. maybe it does read 10% low or maybe it doesn't - point is that i don't know...
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Re: 4iiii precision power meter, my experience

Postby ItsDank » Fri Oct 23, 2015 9:43 pm

march83 wrote:yeah, i understand the difference completely, i was just trying to demonstrate the limitations of a single sided power measurement in an over-simplified manner. maybe it does read 10% low or maybe it doesn't - point is that i don't know...


I think even if it's out, in a large sense it doesn't matter, especially if it is out in a predictable manner (like always 10 percent wrong). With single sided power there's always going to be an inconsistency comparing to dual sided power configurations and in the end, if you still get a training benefit out of it or can race to a certain wattage prior to hitting threshold then it's doing a good job?

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Re: 4iiii precision power meter, my experience

Postby Alex Simmons/RST » Sat Oct 24, 2015 7:02 am

ItsDank wrote:
march83 wrote:yeah, i understand the difference completely, i was just trying to demonstrate the limitations of a single sided power measurement in an over-simplified manner. maybe it does read 10% low or maybe it doesn't - point is that i don't know...


I think even if it's out, in a large sense it doesn't matter, especially if it is out in a predictable manner (like always 10 percent wrong). With single sided power there's always going to be an inconsistency comparing to dual sided power configurations and in the end, if you still get a training benefit out of it or can race to a certain wattage prior to hitting threshold then it's doing a good job?


march83's experience of consistent (pseudo) power balance is more the exception than the rule. It's more common/normal for it to be variable.

As with all things power data related, the quality of data you require depends on what you intend to use it for. If you only need something within 10%, then I'd say it's role is mostly as a motivation aid and/or a gateway drug to learning the use of power as at that level of precision training can be easily managed without a power meter.

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Re: 4iiii precision power meter, my experience

Postby Alex Simmons/RST » Sat Oct 24, 2015 7:04 am

march83 wrote:yeah, i understand the difference completely, i was just trying to demonstrate the limitations of a single sided power measurement in an over-simplified manner. maybe it does read 10% low or maybe it doesn't - point is that i don't know...

Cool. It's not always an obvious distinction for many, hence why I mention it from time to time.

More info here for anyone interested:
http://alex-cycle.blogspot.com.au/2013/ ... lance.html

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Re: 4iiii precision power meter, my experience

Postby ItsDank » Sat Nov 14, 2015 5:33 pm

Alex Simmons/RST wrote:
ItsDank wrote:
march83 wrote:yeah, i understand the difference completely, i was just trying to demonstrate the limitations of a single sided power measurement in an over-simplified manner. maybe it does read 10% low or maybe it doesn't - point is that i don't know...


I think even if it's out, in a large sense it doesn't matter, especially if it is out in a predictable manner (like always 10 percent wrong). With single sided power there's always going to be an inconsistency comparing to dual sided power configurations and in the end, if you still get a training benefit out of it or can race to a certain wattage prior to hitting threshold then it's doing a good job?


march83's experience of consistent (pseudo) power balance is more the exception than the rule. It's more common/normal for it to be variable.

As with all things power data related, the quality of data you require depends on what you intend to use it for. If you only need something within 10%, then I'd say it's role is mostly as a motivation aid and/or a gateway drug to learning the use of power as at that level of precision training can be easily managed without a power meter.


I ordered :)

Never had a power meter before so it'll be quite a while till I actually learn how to use the data to benefit my training. Probably the most obvious use initially would be to find what my threshold power is so I know if I'm slowly ruining myself during a race.

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Re: 4iiii precision power meter, my experience

Postby 3DKiwi » Sun Nov 15, 2015 4:18 am

I've had a 4iiii PM since about June. I'm very happy with it. Battery life has been an issue and if I'm going to be transporting my bike I take the battery out. You only have to bump the bike ever so slightly and the PM wakes up. Hopefully the new firmware update will help.

The only issue I had was when the battery ran out. After replacing the battery I wasn't getting any power output. Just a matter of doing a factory reset using the Android app.

What I've found is out on the road I don't really bother using / watching my power as it fluctuates so much depending on road conditions etc etc. It's much more use on a Trainer and doing Trainerroad.com workouts with power profiles. For outside I analyze the power after the ride.

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Re: 4iiii precision power meter, my experience

Postby ItsDank » Sun Nov 15, 2015 10:07 am

3DKiwi wrote:I've had a 4iiii PM since about June. I'm very happy with it. Battery life has been an issue and if I'm going to be transporting my bike I take the battery out. You only have to bump the bike ever so slightly and the PM wakes up. Hopefully the new firmware update will help.

The only issue I had was when the battery ran out. After replacing the battery I wasn't getting any power output. Just a matter of doing a factory reset using the Android app.

What I've found is out on the road I don't really bother using / watching my power as it fluctuates so much depending on road conditions etc etc. It's much more use on a Trainer and doing Trainerroad.com workouts with power profiles. For outside I analyze the power after the ride.


3 second moving average? I've got to do a heap more research on how to use power for training.

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Re: 4iiii precision power meter, my experience

Postby kb » Sun Nov 15, 2015 10:42 am

ItsDank wrote:
3DKiwi wrote:What I've found is out on the road I don't really bother using / watching my power as it fluctuates so much depending on road conditions etc etc. It's much more use on a Trainer and doing Trainerroad.com workouts with power profiles. For outside I analyze the power after the ride.


3 second moving average? I've got to do a heap more research on how to use power for training.

3 second + lap for intervals.
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Re: 4iiii precision power meter, my experience

Postby panosk » Mon Nov 23, 2015 2:35 pm

A few days ago they announced a firmware upgrade. The new features are:

1. Pedal smoothness for the left leg.

2. Torque effectiveness for the left leg.

3. Improved battery life by 25%.
(my comment: that means that from the expected 80h that was up to now, which from my experience was 57 and 54 hour of riding with two different batteries, it now goes up to an expected 100h).

4. Battery status indicator.
(my comment: as a % in their app and as ok/low in garmin computers)

5. Improvements to Zero Offset allow for robust and reliable handling of calibration values, thus maintaining accuracy.

6. Adjustment Scale Factor was introduced to address the fact that PRECISION is (currently) a left-only power meter, and not everybody has a 50/50 left-right balance. Perhaps from training on some different equipment, you know that your left leg is actually weaker and you have a 45/55 left-right balance. Doubling the power from your left leg (as per PRECISION and all single sided power meters), gives you a total power of only 90% of what you’re actually putting out. In order to adjust for this, you can simply set the scale factor to 50/45=1.11111. 50 because 50% is your desired reading for PRECISION (half of your total power output), and 45 because your left leg is actually only putting out 45% of your actual total power. This scale factor can also be used to match PRECISION’s output to other training equipment you use.
...each turn of the pedals, every single meter gained, hurts...

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Re: 4iiii precision power meter, my experience

Postby ItsDank » Mon Nov 23, 2015 3:38 pm

panosk wrote:A few days ago they announced a firmware upgrade. The new features are:

1. Pedal smoothness for the left leg.

2. Torque effectiveness for the left leg.

3. Improved battery life by 25%.
(my comment: that means that from the expected 80h that was up to now, which from my experience was 57 and 54 hour of riding with two different batteries, it now goes up to an expected 100h).

4. Battery status indicator.
(my comment: as a % in their app and as ok/low in garmin computers)

5. Improvements to Zero Offset allow for robust and reliable handling of calibration values, thus maintaining accuracy.

6. Adjustment Scale Factor was introduced to address the fact that PRECISION is (currently) a left-only power meter, and not everybody has a 50/50 left-right balance. Perhaps from training on some different equipment, you know that your left leg is actually weaker and you have a 45/55 left-right balance. Doubling the power from your left leg (as per PRECISION and all single sided power meters), gives you a total power of only 90% of what you’re actually putting out. In order to adjust for this, you can simply set the scale factor to 50/45=1.11111. 50 because 50% is your desired reading for PRECISION (half of your total power output), and 45 because your left leg is actually only putting out 45% of your actual total power. This scale factor can also be used to match PRECISION’s output to other training equipment you use.


Awesome, my crank took two days to reach Germany from Australia, looking forward to it.

In regards to left/right balance, we'd need to get on someone's bike that has dual power to estimate?

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Re: 4iiii precision power meter, my experience

Postby Alex Simmons/RST » Mon Nov 23, 2015 4:52 pm

panosk wrote:A few days ago they announced a firmware upgrade. The new features are:
6. Adjustment Scale Factor was introduced to address the fact that PRECISION is (currently) a left-only power meter, and not everybody has a 50/50 left-right balance. Perhaps from training on some different equipment, you know that your left leg is actually weaker and you have a 45/55 left-right balance. Doubling the power from your left leg (as per PRECISION and all single sided power meters), gives you a total power of only 90% of what you’re actually putting out. In order to adjust for this, you can simply set the scale factor to 50/45=1.11111. 50 because 50% is your desired reading for PRECISION (half of your total power output), and 45 because your left leg is actually only putting out 45% of your actual total power. This scale factor can also be used to match PRECISION’s output to other training equipment you use.

Pedalling asymmetry is not a constant but varies due to many factors.

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Re: 4iiii precision power meter, my experience

Postby ItsDank » Mon Nov 23, 2015 5:05 pm

Alex Simmons/RST wrote:Pedalling asymmetry is not a constant but varies due to many factors.


Do you think the variance would be a major performance factor?

Would the over, under reporting of power, if relying on it during a race to gauge your pace or effort cause you to hit the wall sooner so to speak? Or would the extra 10w over or under not be that significant generally?

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Re: 4iiii precision power meter, my experience

Postby Alex Simmons/RST » Mon Nov 23, 2015 8:16 pm

ItsDank wrote:
Alex Simmons/RST wrote:Pedalling asymmetry is not a constant but varies due to many factors.


Do you think the variance would be a major performance factor?


That depends on what you mean by performance factor. Performance of a power meter is based on range of factors, of which one of them is accuracy fit for purpose. What level of accuracy you need depends on what you intend to use the data for.


ItsDank wrote:Would the over, under reporting of power, if relying on it during a race to gauge your pace or effort cause you to hit the wall sooner so to speak? Or would the extra 10w over or under not be that significant generally?

Given that's one of the lo fi uses of a power meter, probably not.

But it is certainly possible if you are unaccustomed to moderating effort based on the interplay between perceived exertion and power.

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Re: 4iiii precision power meter, my experience

Postby ItsDank » Mon Nov 30, 2015 3:14 pm

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Alright, so the process is fairly simple. You head to their website, order ($399 USD), print out the Fedex documents they give you, take your crank arm to any Fedex shipping retailer (mine was the local printers) and then it gets sent, installed and sent back.

I ordered on the 23rd and my crank went to Canada two days after, got installed and sent back today, the 30th. That is quite frankly insane, especially when they list 2 to 3 weeks as an installation timeline.


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They have a crank compatibility list and mine wasn't on it. It only took one email and they immediately confirmed that they would do an install on my frankly ageing Dura Ace 7900 crank.

I'm at work but I'll install it tonight and give it a bit of a test run tomorrow if I get the chance.

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Re: 4iiii precision power meter, my experience

Postby ItsDank » Wed Dec 02, 2015 10:22 am

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I stripped a bolt on the crank arm as I don't have a torque wrench but after getting a replacement, the unit is on and working.


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I'm heading out to Centennial Park tomorrow morning to do some sprints so hopefully I'll get some good data out of it then.

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Re: 4iiii precision power meter, my experience

Postby 3DKiwi » Wed Dec 02, 2015 12:03 pm

ItsDank wrote:ItsDank


Have fun.

Make sure you're running the latest firmware version. A new version came out about a week ago.

I'm still very pleased with my 4iii.

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Re: 4iiii precision power meter, my experience

Postby ItsDank » Wed Dec 02, 2015 1:25 pm

3DKiwi wrote:
ItsDank wrote:ItsDank


Have fun.

Make sure you're running the latest firmware version. A new version came out about a week ago.

I'm still very pleased with my 4iii.


Yeah the update through the app was pretty easy. I'm doing the 5 beach hills in Sydney tomorrow so I hopefully get some figures up in this thread then.

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Re: 4iiii precision power meter, my experience

Postby ItsDank » Thu Dec 03, 2015 10:32 am

So that was interesting.

https://www.strava.com/activities/443350856/analysis

Did a casual few hills around Sydney with the local club and it's pretty nifty trying to gauge your efforts with power. I don't feel like I can sustain 350-400w for more than a few minutes at best and my Garmin calculated that my FTP is around 230w although that figure should be higher if I do a consistent 20 minute test.

Anzac Parade is a bit of fun, had a few sprints in between the traffic lights.
https://www.strava.com/activities/44335 ... /4435/4869

I sustained above 1000w for at least 300m and had to chill out when my HR alarm went off just before 250bpm. That might be a limiting factor more so than the power unfortunately.

All well and good, once the legs are feeling fresh I might do a crit on Saturday to get a real feel for actual FTP and estimated Vo2 max. Hopefully I can just set that and start training in power zones.

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Re: 4iiii precision power meter, my experience

Postby dalai47 » Thu Dec 03, 2015 10:41 am

ItsDank wrote:I might do a crit on Saturday to get a real feel for actual FTP and estimated Vo2 max. Hopefully I can just set that and start training in power zones.


http://alex-cycle.blogspot.com.au/2008/05/the-seven-deadly-sins.html

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Re: 4iiii precision power meter, my experience

Postby ItsDank » Thu Dec 03, 2015 10:51 am

dalai47 wrote:
ItsDank wrote:I might do a crit on Saturday to get a real feel for actual FTP and estimated Vo2 max. Hopefully I can just set that and start training in power zones.


http://alex-cycle.blogspot.com.au/2008/05/the-seven-deadly-sins.html



Awesome read, will have to take the points into consideration prior.

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I honestly felt like I could power through but I've been told to keep the HR below 240 by the cardiologist (probably good advice).

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