New powermeter rumours

Discuss light weight issues concerning road bikes & parts.
mds
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by mds

rruff wrote:How has it made you faster?


There is lots written on how power feedback can help improve performance and endurance. It gives great feedback that lets you experiment and see what works and what does not. One example: power has helped me work on my pacing - smoothing out my output - more watts on the flats and the flatter parts of my climbs - less watts on the steeper parts. This led to improvements in my endurance and average power.

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ergott
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by ergott

rruff wrote:How has it made you faster?


For me, I've found out what my strengths and weaknesses actually are and I was surprised. I've also learned about "matches" and how to burn them.

I'm learning how to better exploit my strengths and hide by weaknesses.

The next step this season is to focus my workouts more.

-Eric

rruff
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by rruff

How does the "match" thing work? I've seen it mentioned and understand the concept, but I'm not sure how to quantify it.

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kytyree
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by kytyree

A match will be different for everyone but it refers to a hard effort having been made. Of course that varies with individuals but each individual has different matches. The examples in the "training with power" book are:

1 mins 20% above threshold
5 mins 15-20% above
10 mins 8-12% above
20 mins 0-8%

But it would take studying files from a rider to define their matches. The next thing to work out is how many matches in the rider's matchbook. A rough example using only one power file is a take a circuit race with one short but steep power climb in each loop. Our rider makes a 20% above threshold effort each time for the first 9 laps and stays attached to the field but on the 10th and last lap goes off the back on the climb and misses the deciding move. You might be able to draw from that power file that our rider has 9 matches if when looking at the 10th lap you see that there was a drop in power output when comparing the 10th climb to the first 9.

This was an important realization for me when I first starting using a powermeter. I often felt like I missed a move I wanted to be in or didn't hang in on a climb because the front of the field took the pace to a level I couldn't hold. Looking at my files though showed I was often just running out of matches. When I was missing moves and so on the field wasn't doing anything I couldn't have done a few minutes ago, I just couldn't do it then. Once you know that you can factor it in to your strategy and you can address it in training.

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J-Nice
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by J-Nice

OK, I think we've beaten the cost/value analysis to death.

What I would like to see, and I mentioned this in the Brim Brothers survey, is a power meter that reads the watts put out by each leg independent of each other.

That to me is a bigger sticking point with the SRM system than the price. I want to know what each leg is doing and not have an approximation based on the values taken from one side and multiplying it by two.

For that type of money, I would like to get maximum accuracy.
Last edited by J-Nice on Sun Mar 01, 2009 5:49 pm, edited 1 time in total.
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kytyree
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by kytyree

You are confusing the method used by Ergomo with the one used by SRM.

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by rruff

kytyree wrote:1 mins 20% above threshold
5 mins 15-20% above
10 mins 8-12% above
20 mins 0-8%


Thanks for those details. Just thinking about it though, that doesn't seem quite right... at least for me. I can produce a lot of 1min efforts at 120%, but 20 min at 108% would be a maximal effort. Actually, the 5-20min efforts look to be close to maximum. How long do you need to recover after burning one, before burning another? Seems like that would be very important.

I participated in an agonizing thread on Wattage awhile ago regarding the accuracy of NP and TSS, etc. I advocated attempting to model the actual physiology, using a riders CP values for all durations. Not only could you model efforts and recovery within a ride or race, but also recovery and refueling for successive days... in other words a 24/7 model of your physiological state (repair, recovery, ability)... and maybe even your psychological state.

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kytyree
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by kytyree

Those numbers certainly wouldn't work for everyone, and like you I would rather do a bunch of short efforts at 20% above than stay a little above threshold for very long. Somewhat beyond my expertise but I think that has a lot to do with a riders power profile (which includes genetics to a degree) and also with what they've trained for.

2 wheels
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by 2 wheels

hockinsk wrote:If you fill out the survey at brim, one of the main questions is "What types of pedals and cleats do you use?" and do you own a Garmin 705. Only a wild stab in the dark with a very blunt sword, but could that suggest a system combined into the cleat and/or shoe with simply Ant+Sport support?

If you look at here http://www.brimbrothers.com/about you can read this message:
Image Brim Brothers is a member of the ANT+ Alliance.


The system could possibly be mounted between the shoe and the cleat.

Super_fast
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by Super_fast

ergott wrote:
STARNUT wrote:sure.

PMs work with starin gauges and bathroom scale work with strain gauges.

I have a bathroom scale the gets down to .01 lbs and it cost me $70. I have a PM that measures down to the .01 ft/lbs and cost $4000. One was manufactured in Germany and one was manufactured in Asia. Granted, the PM does velocity as well but so does a $40 cycling computer.

Starnut


You have a bathroom scale that does 0.01lbs? Mine does tenths.

Another thing to consider about PM is that you need 0.01 accuracy over a much higher range. No bathroom scale I know of reads 2000lbs with that kind of accuracy. I'm no expert, but I think that proper strain gauges like the ones used in an SRM are the biggest cost. I don't pretend to know this for sure. I'd like to hear an answer to that from someone more in the know.

The other factors such as reliability, spinning gauges, waterproofing, and battery life are also added in there.


A number on a digital display means nothing at all. A lot of people think more numbers is more accurate, but it isn't so simply. Let's take a SRM as example and a powerfull sprinter. The accuracy of the SRM is -/+ 2%, he is sprinting at 2000 Watt. So the readings on the screen can be somewhere between 1960 and 2040 Watts, quite some difference. But on the screen you can see changes of 1 Watt, when that 1 Watt would have been significant the accuracy would have been 0,1% or even better.

The 8 strain gauges in a SRM cost probably less then €10. SRM's are just way over-priced. €900 for the computer, which isn't high end at all... Programming the microcontrollers isn't rocket science, PCB layout is also not too hard for such a simple device. You don't need to have a masters degree in EE to develop a powermeter.

But there are more peeps working on a affordable powermeter. :wink:

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J-Nice
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by J-Nice

Super_fast wrote:The 8 strain gauges in a SRM cost probably less then €10. SRM's are just way over-priced. €900 for the computer, which isn't high end at all... Programming the microcontrollers isn't rocket science, PCB layout is also not too hard for such a simple device. You don't need to have a masters degree in EE to develop a powermeter.

But there are more peeps working on a affordable powermeter. :wink:


Thank you for putting this into perspective.

+1 for you!!! And Godspeed to the peeps who are currently hard at work to bring us something affordable and technically up-to-date.
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hockinsk
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by hockinsk

2 wheels wrote:
hockinsk wrote:If you fill out the survey at brim, one of the main questions is "What types of pedals and cleats do you use?" and do you own a Garmin 705. Only a wild stab in the dark with a very blunt sword, but could that suggest a system combined into the cleat and/or shoe with simply Ant+Sport support?

If you look at here http://www.brimbrothers.com/about you can read this message:
Image Brim Brothers is a member of the ANT+ Alliance.


The system could possibly be mounted between the shoe and the cleat.


By 'with simply Ant+Sport support' I was meaning to suggest it might be available 'without' a head unit to keep cost down. i.e. for 705 users. $300 of a powertap is just the cost of the head unit, but you can't buy a Powertap 'without' the display.

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ergott
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by ergott

hockinsk wrote:but you can't buy a Powertap 'without' the display.


Actually, you can. I've sold several PT to users without selling the computer. They sell the hub only as well.

-Eric

2 wheels
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by 2 wheels

hockinsk wrote:By 'with simply Ant+Sport support' I was meaning to suggest it might be available 'without' a head unit to keep cost down. i.e. for 705 users. $300 of a powertap is just the cost of the head unit, but you can't buy a Powertap 'without' the display.

I agree with you, just wanted to point out that the power meter will probably be ANT+ compatible (cycle computer included or not) since they are a member of the ANT+ Alliance.
ANT+ seems to become a common wireless standard among power meters and cycle computers. With a common standard in place it could make a lot of sense for them to only focus on the power sensor and just let it interface with third party Ant+ cycle computer like Garmin 705. And since they ask if you already own a Garmin 705 in their survey, it's very likely they wont include a cycle computer.

You can read a lot between the lines by reading the questions in their survey. Their website for example doesn't mention anything about where the power sensor is placed (like hub, BB, cranks, pedals cleats or shoes). But the survey doesn't ask what kind of hubs, cranks or shoes poeple use, but only what kind of pedals people use. If the power sensor wasn't attached somewhere to the cleats or pedals then they would probably not ask what kind of pedals people use.

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Coolhand
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by Coolhand

More vaporware has been inflicted on us by these random powermeter sorts who say its easy and cheap to do this and get into to to find out a bike is an unforgiving place, and that the service and software is critical (and expensive). People keep using SRM and Saris because the products works and they have the service and warranty aspects down.

Everything else so far has been junk, vaporware, crappy watt estimators, or pushed out with significant issues. Powermeters and wheel builders, you get what you pay for.
This forum would be a better place if you had to know what you were talking about prior to posting. And if you took yourself less seriously.

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