First power meter - guidance and feedback please

[defy1]

I have to say my 4iii has been bullet proof for the past year. I don't think about it or worry about it, it just works.
About $700 from direct from the US.

[MichaelB]

Hiya defy1 - great that the 4iii has been working for you. How have you found using it ?

The Zayante crankset with the 4iii was almost a goer until it needed a specific (and exxy unique) BB to make it work.

Looking fwd to getting mine, just waiting on confirmation from P2M Aus whether it’s the Type S or NGeco.

[eeksll]

My NGeco is coming with the first batch that Sam gets. It was $1099 with the Rotor 3D24 cranks, which works out to around $699 for just the spider.

which if i read correctly, that is the same price as the type S on their site now.

[queequeg]

My NGeco is coming with the first batch that Sam gets. It was $1099 with the Rotor 3D24 cranks, which works out to around $699 for just the spider.

which if i read correctly, that is the same price as the type S on their site now.

The Type-S price is only a special. The regular type-S price was $1099.

I am guessing that once the NGEco hits the market, the Type-S is gone.

[eeksll]

My NGeco is coming with the first batch that Sam gets. It was $1099 with the Rotor 3D24 cranks, which works out to around $699 for just the spider.

which if i read correctly, that is the same price as the type S on their site now.

The Type-S price is only a special. The regular type-S price was $1099.

I am guessing that once the NGEco hits the market, the Type-S is gone.

hmmm, ok, thanks. A bit more than I want to spend, but lets see how I feel when they actually come out

[defy1]

Hiya defy1 - great that the 4iii has been working for you. How have you found using it ?

The Zayante crankset with the 4iii was almost a goer until it needed a specific (and exxy unique) BB to make it work.

Looking fwd to getting mine, just waiting on confirmation from P2M Aus whether it’s the Type S or NGeco.

Its being faultless and trouble free since I got it. I am a weekend warrior, so all I want is a consistent power reading, and 4iii delivers for me.
Never had any drop outs or technical issues. I ride in rain and all sorts of weather, and wash it with a pressure hose lol and still fine.
Only minor first-world-problems downside, is you need to 'zero' it before every ride, but it taks 5 secs and now its part of my routine like putting on a helmet.

[Alex Simmons/RST]

Only minor first-world-problems downside, is you need to 'zero' it before every ride, but it taks 5 secs and now its part of my routine like putting on a helmet.

Doing a manual torque zero check/ reset is a habit of every single power meter user who cares about their data quality.

Do it. Every single time. Check it along the way occasionally as well if the opportunity presents.

[adam0bmx0]

Can't fualt my Ultegra 4iiii left-arm power meter either. Got it from Merlin cycles in the UK when they had a discount on them, think it was around $560 posted!

Been great, no dropouts, links to my Wahoo Bolt fine.

On the hunt now for a Sram Red BB30 power meter, no left arms about, unless I go Stages (custom left carbon crank arm) and thier seperate spindle, but then I'll have odd left and right crank arms.

Or I go Quarq, which is like $1600 for a complete crankset......

[trailgumby]

From memory the P2M Type S does an auto-zero every time you cease pedalling for a few seconds.

power2max power meters automatically update the zero offset when you stop pedaling. Anytime you stop pedaling long enough (approximately 3 seconds or more) power2max updates the zero offset. You can also update the zero offset manually through a compatible head unit.If you perform a manual zero offset via a head unit (for example at the start of a TT), the auto zero is then disabled for the next 5 crank revolutions.

http://www.power2max.com.au/support/faq/

[march83]

quarq zeroes if you backpedal 4 times
powertap zeroes when you roll

problem is that there's no confirmation when it happens, there's no record in the FIT files of the value, there's no way to know that a zero has occurred accurately. not an ideal situation.

[Alex Simmons/RST]

From memory the P2M Type S does an auto-zero every time you cease pedalling for a few seconds.

power2max power meters automatically update the zero offset when you stop pedaling. Anytime you stop pedaling long enough (approximately 3 seconds or more) power2max updates the zero offset. You can also update the zero offset manually through a compatible head unit.If you perform a manual zero offset via a head unit (for example at the start of a TT), the auto zero is then disabled for the next 5 crank revolutions.

http://www.power2max.com.au/support/faq/

Don't start me on auto zero....

[BugsBunny]

I use the PowerPod.

Its not perfect and there are few pro's and cons - but worth a consideration if you don't want to spend the big dollars.

Pros -
Very low cost (comparatively).
Its combined L/R power - so not single sided power.
In comparison to my Neo power - I find the hill climbing power to be very aligned with my perceived effort.
You can move it around/flexibility with other bikes / mods you might later plan on your bike.
Second hand ones should be fine to buy as less mechanical bits for wear and tear.

Cons -
In heavy rain it won't work properly - wind port blocked.
The software is clunky - so you need to fiddle around to get the calibration "right".
My perceived power on the flats doesn't seem to be as accurate as for climbing.
You cannot use your PowerPod with indoor trainers.
Its not instantaneous power - it takes a few seconds for it to "catch up".

PS - its on sale TODAY only. USD$199/235 depending on ANT+ or BT/ANT+ model.
https://velocomp-llc.myshopify.com/coll ... ower-meter
Bugs

[PiratePete]

right now I'm too chicken to take the battery out to see if it's wet, I'm hoping not.

Do it, and if wet, shove the pedal in a jar of rice.

I have a pair of P1, first pair rode in plenty of rain, then a real soaking including a 5km descent with a centimetre of rain on the road. A few days later started playing up, remove battery it was damp. Replaced under warranty (old distributor), that pair lasted less than six months, bearing issue, took pushys almost 4 months to replace under Powertap 2 year warranty.

HI @nickobec, I did check a day or so after your post (haven't had a chance to update the post), and they were both happy and dry inside. When I received them I applied a healthy amount of wool grease to the threads of the battery covers due to your posts elsewhere here. Maybe this saved the day. At least I'm now confident that the PowerTap P1 will survive at least 70km of drenching QLD rain.

[Greatwhite7]

Garmin Vector 3S.
Single side power meter.
About 120 hour battery.
Easy swap.
About $750 if you can source them overseas.

Unless you are pro I was advised single side would be adequate enough.

[trailgumby]

From memory the P2M Type S does an auto-zero every time you cease pedalling for a few seconds.

<snipped>

http://www.power2max.com.au/support/faq/

Don't start me on auto zero....

Erm...

[PiratePete]

Unless you are pro I was advised single side would be adequate enough.

Depends on what your looking for I suppose. It's not all about total power...

[Alex Simmons/RST]

From memory the P2M Type S does an auto-zero every time you cease pedalling for a few seconds.



http://www.power2max.com.au/support/faq/

Don't start me on auto zero....

Erm...

Think for a moment about the concept of zeroing a measurement device while the device is being used... In this case zeroing the torque/force readings from spider/crank/pedal based strain gauges while you are clipped into the pedals.

The whole point of testing a zero torque value is to ensure no torque is being applied.

I challenge anyone to set up their meter and head unit such that their torque readings are on display, and while clipped into the pedals attempt to have a stable TZ value that reliably matches their unloaded TZ value.

Then of course there is the other matter previously mentioned - there is no log of changes in torque zero. You don't know when they occurred nor how much the change was. If you care about data accuracy, then this stuff matters.

[Alex Simmons/RST]

Garmin Vector 3S.
Single side power meter.
About 120 hour battery.
Easy swap.
About $750 if you can source them overseas.

Unless you are pro I was advised single side would be adequate enough.

Single sided measurement simply means greater imprecision and uncertainty in the data (for the simple fact that asymmetry in power production is both normal and variable).

The consequences of that are the utility of the data declines. Yes you can do some of the stuff that you can do with other power meter data but the sort of stuff you can do with this level of data quality is not a lot more than can be achieved with a watch, perceived exertion and/or a heart rate monitor.

The applications of data with this level of uncertainty are what I call "low-fi" applications.

That said, single sided meters are what we might call a gateway drug into training with power. It can help you learn about some basic principles and applications.

[MichaelB]

That said, single sided meters are what we might call a gateway drug into training with power. It can help you learn about some basic principles and applications.

Hope I don't get tested then ...

[Alex Simmons/RST]

Power is a drug, didn't you know?!?!

[trailgumby]

Don't start me on auto zero....

Erm...

Think for a moment about the concept of zeroing a measurement device while the device is being used... In this case zeroing the torque/force readings from spider/crank/pedal based strain gauges while you are clipped into the pedals.

I get the theory and can see that having a material effect on pedal based power meters, but when it's on the spider and no torque is being applied between the spindle and the chainrings while you are coasting I struggle to see that it is having an effect on the data of sufficient magnitude that it would affect your decision making, given that accuracy is +/-2% anyway.

Am I missing an important distinction? If so, I'm keen to learn.

Comparing it to my late and unlamented Quarq S2275, it is a lot less hassle. In the half-hour it took me to get from home to the intersection of Forest Way and Mona Vale Roads, temperature change seemed to cause the readings to drift downwards quite a bit, and if I forgot to pedal backwards 5 times then the TSS would be way down for the ride. PMs read low for TSS for MTB anyway compared to hrTSS due to the greater use of the upper body when controlling and pumping the bike for speed, but this would read low by something like 15-25 watts until I re-zeroed it.

[MichaelB]

Seeing some good discussion and looking fwd to getting my 'dose' of the power drug (as Alex put it), but have to wait a bit for it to come into stock.
Doing plenty of reading in the meantime and using HR as a guide, and doing 'practice' 30 min efforts for when the 1st FTP test is ready to be done. There is a good climb in Adelaide for this - Greenhill Rd which is 7.3km (AT) 6.6%. Did a PB there the other day at 31:31 (avg. HR was 172bpm, so was giving it a bit of wellie ).

Fingers crossed that it comes soon

[Alex Simmons/RST]

Erm...

Think for a moment about the concept of zeroing a measurement device while the device is being used... In this case zeroing the torque/force readings from spider/crank/pedal based strain gauges while you are clipped into the pedals.

I get the theory and can see that having a material effect on pedal based power meters, but when it's on the spider and no torque is being applied between the spindle and the chainrings while you are coasting I struggle to see that it is having an effect on the data of sufficient magnitude that it would affect your decision making, given that accuracy is +/-2% anyway.

Am I missing an important distinction? If so, I'm keen to learn.

Put your bike on a trainer and try it. Like I did in this blog post and video showing the impacts on torque zero values:
http://alex-cycle.blogspot.com.au/2013/ ... ffset.html

As for real world impact of an auto zero, here's an impromptu experiment I did to show the issue:
http://alex-cycle.blogspot.com.au/2013/ ... zen_7.html

Comparing it to my late and unlamented Quarq S2275, it is a lot less hassle. In the half-hour it took me to get from home to the intersection of Forest Way and Mona Vale Roads, temperature change seemed to cause the readings to drift downwards quite a bit, and if I forgot to pedal backwards 5 times then the TSS would be way down for the ride. PMs read low for TSS for MTB anyway compared to hrTSS due to the greater use of the upper body when controlling and pumping the bike for speed, but this would read low by something like 15-25 watts until I re-zeroed it.

Better design of the way strain gauges are set up minimises temperature induced drift. Nowadays some meters use firmware instead to make up for a lack of this feature.

[trailgumby]

Seeing some good discussion and looking fwd to getting my 'dose' of the power drug (as Alex put it), but have to wait a bit for it to come into stock.
Doing plenty of reading in the meantime and using HR as a guide, and doing 'practice' 30 min efforts for when the 1st FTP test is ready to be done. There is a good climb in Adelaide for this - Greenhill Rd which is 7.3km (AT) 6.6%. Did a PB there the other day at 31:31 (avg. HR was 172bpm, so was giving it a bit of wellie ).

Fingers crossed that it comes soon

I've been reading Allen and Coggan's book - they have a slightly different approach to doing the FTP test. I don't think it's going to be any less uncomfortable though I'll probably give it a crack on the weekend after next to set a baseline. Next week is a recovery week.

In other news the weight training program seems to be yielding results. After 4 weeks of discomfort after restarting with easy weighs and high reps (20-30), I've started bumping up the middle set and dropping reps. I'm feeling more solid on the bike with fewer aches and pains in the joints and connective tissues, although the glutes are letting me know they have been getting worked over. That's no bad thing as I have historically had a habit of underutilising both them and my VMOs.

[macca33]

From memory the P2M Type S does an auto-zero every time you cease pedalling for a few seconds.

power2max power meters automatically update the zero offset when you stop pedaling. Anytime you stop pedaling long enough (approximately 3 seconds or more) power2max updates the zero offset. You can also update the zero offset manually through a compatible head unit.If you perform a manual zero offset via a head unit (for example at the start of a TT), the auto zero is then disabled for the next 5 crank revolutions.

http://www.power2max.com.au/support/faq/

Don't start me on auto zero....

Yep, I don't like the P2Max auto-zero and would disable it if I could, but there is no option to on my Garmin. I like everything else about my P2M though!

cheers