Power meters

[T.M.H.N.E.T]

Just out of curiosity what has the temperature to do with power? Is it something to do with the sensor?

Shaun

Measuring power is simple in a controlled environment, but when you’re out in the elements facing varying climates everything changes. The strain gages used to determine power, whether it be crank based, spider-based, pedal based, etceteras, are highly affected by changes in temperature. If a power meter system does not take into consideration changing temperatures throughout a ride, power will be wildly inaccurate.

Why do changing temperatures affect power? Strain gages are tiny metallic wires laid across a metal crank, spider, pedal etc. It is the flexing of these wires that measure torque. When these wires heat up or cool down in response to external temperatures they naturally expand and contract. This results in false data.

Stages Power meters are equipped with ATC – [Active Temperature Compensation]. Different temperatures cause strain gages to expand and contract a specific amount. ATC allows the power meter to compensate for temperature changes that would otherwise affect the strain gages and their ability to accurately measure force. More importantly, Stages ATC auto-adjusts on the fly, without the need to stop pedaling.

And being the owner of a stages, I usually leave my bike outside long enough for my garmin to fix gps (glonass turned off) and lock the front door. Get on and ride with no noticable adverse effects.

 

[midlife]

Thanks

Shaun

 

[HarryTheDog]

Ive not read the book but power is power regardless of your age. I guess it'll have instructions how to establish your Functional Threshold Power (FTP) and will have training zones based on that.

Oh well I have downloded it to my kindle, I am off working in Portugal for a week so will have plenty of time to read and digest it before the meters arrive. Hopefully it'll give me a clue as to why my CX performance was so cack this morning.

 

[MistaDee]

Oh well I have downloded it to my kindle, I am off working in Portugal for a week so will have plenty of time to read and digest it before the meters arrive.

Its pretty heavy reading, be prepared to go through it a couple of times, but its reknown as the power meter bible.
The author also created the highly regarded training peaks WKO+ power meter analysis software

 

[Cuchilo]

And being the owner of a stages, I usually leave my bike outside long enough for my garmin to fix gps (glonass turned off) and lock the front door. Get on and ride with no noticable adverse effects.

Would you upgrade your stages to P1s ? Would you even call it an upgrade ?

 

[S-Express]

It isn't an upgrade. It's just two different choices of powermeter.

 

[T.M.H.N.E.T]

Would you upgrade your stages to P1s ? Would you even call it an upgrade ?

At this time no, I swap the stages between bikes and would want to keep the ability to choose pedal type. I use my winter bike as a cx bike also so want mtb pedals

 

[MistaDee]

The following URL has some reasonable information regarding purchasing a power meter. I would not say I agree with the article 100% but I think its fair. There are as many opinions as power meters around.

http://www.bicycling.com/bikes-gear/reviews/what-to-know-before-buying-a-power-meter

 

[Cuchilo]

Still undecided If Sigma had a stages in stock yesterday then i would be an owner now but having come away empty handed and more time to think i'm back where i started
What i know for sure is its between stages and P1s . I decided this when building the bike up and buying the groupset .
Stages seems to me like a more robust PM in other words there are less moving parts to go wrong . If its going to give me the same end result it seems like the safer option . But P1's for just a little bit more , i'm just not sure what more they will give me

 

[S-Express]

But P1's for just a little bit more , i'm just not sure what more they will give me

It gives you a pedal-based meter, rather than a crank arm based meter. It's just two different ways of measuring the same output. Don't over-think it.

 

[MistaDee]

But P1's for just a little bit more , i'm just not sure what more they will give me

I looked at P1's and decided against them for the following reasons.

1. The cleats are specifically designed for use with P1 pedals although they look very similar to Look cleats they are subtly different. Look cleats do fit the pedals but the fit/engagement is not optimal. Unfortunately the correct cleats are not as widely available as look cleats.
   
2. There is an issue with clipping in, the weighting of the pedals means that they don’t always sit in the optimum orientation for this compared to Look and Shimano pedals, which despite being single sided, will naturally sit at angle ideal for cleat insertion.
   
3. The weight, P1 pedals weigh 437g a pair. A pair of Dura-Ace pedals weigh 250g and Garmin Vector pedals and pods hit the scales at 351g so they are pretty beefy
4. They are beyond fugly.

I ended up with Vectors and also have a Quarq SRAM which im very happy with

 

[Hacienda71]

I bought Bepro. Cheap and get pretty good reviews on DC Rainmaker. Use standard Look cleats which I use anyway. Had them for a few months and they have been fine.

 

[HarryTheDog]

Just as an-aside, my Zone DPMX meters fell through, the feckin company went bust 3 days ago .
However what might be of interest to other people is that I was half regretting ordering them already as they were speedplay specific and would not go on my other bikes so I started searching in desperation for a power meter that would do all 3 of my bikes , ( Road MTB and CX all different pedals different cranks and even a different BB for good measure) and I found the LIMIT power meter which screws into the crank arm where your pedals normally screw in and then you screw the pedal into them. Left hand only, spacer for the right. This of course pushes the pedals out farther but is not supposed to be a problem. I was put off because they were only on Indiegogo, a crowd funding site and I had just lost all my my money on kickstarter. however these guys have actually delivered to people. I managed to get one on e-bay this morning .
They are cheep on Idiegogo at 289USD ( I got it even cheaper) when they go into full production 384USD.
Ok under test they might not be the best and only one side and have already proved to need a new firmware download to sort a problem but can go on ANY bike with standard pedal threads. So if anyone is contemplating might be worth a look. Note there are a couple more on ebay as well.

 

[stumpy66]

I don't want to hijack the op's thread but just a quick question. Does this book when helping with training with powermeters compensate for age? just I have set of Zone DPMX power meters on order and wonder if being in my fifties would I follow the same training as a 20yr according to the book.

@HarryTheDog Your talking about your recovery time etc, if your following a structured plan according to your ftp then it's more about how much training stress you can handle and then how much recovery time you need to be able to do the next session.

Recovery time imo is the main issue as you get older, I'm 50 now and use trainer road, I can still put in the miles, at pace but i might need an extra day to recover before I could do another hard session. Hope that's helpful

 

[stumpy66]

@HarryTheDog try Joe Friels Fast after fifty book, lots of good advice in their too