Road Bike Racing - New Power Meter

Since no one's posted it here yet... Looks like it could be interesting, though I don't like the limited crank choice.

http://quarq.us/index.php?option=com_frontpage&Itemid=1

I get the impression it's supposed to be cheaper -- like, PT cost.

I'm going to check it out at interbike but the vunerability to a chain drop is a problem and limited crank options so far.

I always love competition in the market place. We shall see if their strain gauge technology will meet SRM's, (think IBM), and their pricing will compete with Power Tap,(think Dell). If they can pull it off EXCELLENT...if not they are another Gateway.

I always love competition in the market place. We shall see if their strain gauge technology will meet SRM's, (think IBM), and their pricing will compete with Power Tap,(think Dell). If they can pull it off EXCELLENT...if not they are another Gateway.

Apple?

Apple=Ergo. Designed for the liberal left

I think it is just a matter of time befor Shimano/Campy/SRAM need some new products to sell and incorporate some strain gauges in their top of the line BBs. They could have very seamless integration with their computers and probably have the engineering/manufacturing prowess to be better than the current products. Wonder why they haven't done this yet?

Wonder why they haven't done this yet?

Probably because you're oversimplifying the integration process. There's a reason why ERGOMO PMs don't use outboard bearings.

Operating System:

Linux

That's enough to make me not intersted in it.

We shall see if their strain gauge technology will meet SRM's.

I hope they beat, not meet the SRM. As an implementation of straingauges, the SRM is average at best. From the Australian Institute of Sport's tests (http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=15235334&query_hl=7&itool=pubmed_docsum):



Accuracy of SRM and power tap power monitoring systems for bicycling.
Gardner AS, Stephens S, Martin DT, Lawton E, Lee H, Jenkins D.

Department of Physiology, Australian Institute of Sport, Australia.

PURPOSE:: Although manufacturers of bicycle power monitoring devices SRM and Power Tap (PT) claim accuracy to within 2.5%, there are limited scientific data available in support. The purpose of this investigation was to assess the accuracy of SRM and PT under different conditions. METHODS:: First, 19 SRM were calibrated, raced for 11 months, and retested using a dynamic CALRIG (50-1000 W at 100 rpm). Second, using the same procedure, five PT were repeat tested on alternate days. Third, the most accurate SRM and PT were tested for the influence of cadence (60, 80, 100, 120 rpm), temperature (8 and 21 degrees C) and time (1 h at ~300 W) on accuracy. Finally, the same SRM and PT were downloaded and compared after random cadence and gear surges using the CALRIG and on a training ride. RESULTS:: The mean error scores for SRM and PT factory calibration over a range of 50 - 1000 W were 2.3 +/- 4.9% and -2.5 +/- 0.5%, respectively. A second set of trials provided stable results for 15 calibrated SRM after 11 months (-0.8 +/- 1.7%), and follow-up testing of all PT units confirmed these findings (-2.7 +/- 0.1%). Accuracy for SRM and PT was not largely influenced by time and cadence; however, power output readings were noticeably influenced by temperature (5.2% for SRM and 8.4% for PT). During field trials, SRM average and max power were 4.8% and 7.3% lower, respectively, compared with PT. CONCLUSIONS:: When operated according to manufacturers instructions, both SRM and PT offer the coach, athlete, and sport scientist the ability to accurately monitor power output in the lab and the field. Calibration procedures matching performance tests (duration, power, cadence, and temperature) are, however, advised as the error associated with each unit may vary.


The PT's strain guages are better designed, which is why it's variance was only +/-0.5% and +/-0.1%.

That's enough to make me not intersted in it.

Why?

I don't care if they beat the SRM or not. That study, however, I would argue with. The results are well within the SRM's claimed tolerance. The SRM also shows less of a variation with temperature.

Of course, that all ignores the fact they only tested one unit. To get a general comparison of two strain gauge devices, i'd rather see several units (at the minimum) of each tested.

...then again, if your PT drops your HR, is their a comparison?


As an implementation of straingauges, the SRM is average at best.

Why?

He likes Microsoft stuff?

That study, however, I would argue with. The results are well within the SRM's claimed tolerance.
Right, they set out to independently confirm those accuracy claims, which they did. I don't see how that's arguing with the study?

Of course, that all ignores the fact they only tested one unit.
Read it again. They tested 19 SRMs and 5 PTs.

(19 SRMs! Can you imagine? That's like $50K of bike schwag!)

Apple=Ergo. Designed for the liberal left

hmm.. kinda off.. I'm definately far from liberal and love my apple products dearly.

The code for their power meter system is open source! That's really cool because it offers two opportunities:

1. People might be able to help tweak the algorithms and make it even more accurate, or just fix bugs
2. People can make up cool apps to go with it or even make the screen show other cool stuff.

I hope this thing is accurate, reliable and affordable 'cause it could be really neat!

http://quarq.us/index.php?option=com_content&task=view&id=13&Itemid=29


AND:

IT HAS GPS!!


The Qranium. The head unit. The brain box. The physical encapsulation of knowledge. The Quarq Qranium is hands down the most powerful, most advanced bicycle computer ever made. It is fully loaded with GPS, a large graphical display, 512 Mb of memory and a Linux operating system. Perhaps most important: the application software will be released as open-source, maximizing flexibility.

Think of all the apps you can write to work with power and GPS! How many watts it takes you to climb # of feet per minute, adjusted by gradient. Or whatever. Wow, this thing could be cool.

http://www.linuxextremist.com/images/ms-red.jpg

The code for their power meter system is open source! That's really cool because it offers two opportunities:

1. People might be able to help tweak the algorithms and make it even more accurate, or just fix bugs
2. People can make up cool apps to go with it or even make the screen show other cool stuff.

I hope this thing is accurate, reliable and affordable 'cause it could be really neat!

http://quarq.us/index.php?option=com_content&task=view&id=13&Itemid=29


AND:

IT HAS GPS!!

I just hope they MAKE IT WATERPROOF. I would trade out all of my Powertap **** for that alone.

Rumor is that it will be priced around the same as the Dura Ace SRM.

Rumor is that it will be priced around the same as the Dura Ace SRM.

Meh, I'll stick with my SRM then. That thing is fuuuugly.

Rumor is that it will be priced around the same as the Dura Ace SRM.

Where'd you hear that? I haven't seen anything and have been curious.

EDIT: Nevermind, just found it on weightweenies.

Probably because you're oversimplifying the integration process. There's a reason why ERGOMO PMs don't use outboard bearings.

Ergomo was probably in development before outboard bearings became commonplace and it would be difficult for a small company (like the ones that make current power meters) to suddenly develop new versions. From the design of the Campy UT cranks it looks like a power meter implementation would even be easier (e.g. stick a little cylindrical battery right in the center of the crank axle to power the sender...).

I suspect Ergomo wasn't designed from the ground up like SRM, PT, etc. It appears similar to optical torque transducers for industrial use. The developer of Ergomo probably thought he could save on R&D and have a better margin borrowing a torque transducer from other applications. I have to wonder how far along he was in adapting it for cyclig use before he realized it wouldn't measure the right leg.

You'd hope they knew that they'd be getting limited data from the first sketch in a notebook. The guys at Ergomo that is.

Promising, but not interested in SRM kinds of pricing at this point.

Anyone hear anything new about the Minoura footbed solution?

It doesn't actually measure torque (just acceleration, right?), which automatically lumps it in with iBike and the Polar, from my point of view.


Promising, but not interested in SRM kinds of pricing at this point.

Anyone hear anything new about the Minoura footbed solution?

It doesn't actually measure torque (just acceleration, right?), which automatically lumps it in with iBike and the Polar, from my point of view.


I thought it measured insole pressure, to get force. Torque is the cross product of force and arm length. So it could work, but I think it will be inaccurate for inefficient pedalers. Doesn't it claim SRM-like accuracy for seated pedaling?

To me, crank-based is the most obvious way of measuring power.

I thought it measured insole pressure, to get force. Torque is the cross product of force and arm length. So it could work, but I think it will be inaccurate for inefficient pedalers. Doesn't it claim SRM-like accuracy for seated pedaling?

Yeah, you measure force and throw in crankarm length with cadence, and you're in business. Not being able to measure upstroke isn't as attractive, but it should come out with calibration. At any rate, it's going to be much more precise than Polar or iBike, but the accuracy would be off. So that would make it just dandy for training, but not for comparison to other riders -- and that comparison should show up in the race results anyway. I understand the Minoura solution is probably just going to have one footbed sensor, but that would only affect accuracy, not precision.

So no updates that anyone's heard of?

hmm.. kinda off.. I'm definately far from liberal and love my apple products dearly.

Hmmm an apple lover and a professed non-liberal. I will have to consult my Joe McCarthy rule book on that one. ;)

Originally Posted by dmotoguy hmm.. kinda off.. I'm definately far from liberal and love my apple products dearly.


Hmmm an apple lover and a professed non-liberal. I will have to consult my Joe McCarthy rule book on that one. ;)

To mess up your theory even further, I am relatively liberal and don't even own an Ipod, much less a mac.

Edit: and I forgot to mention that I'm North Korean, so theoretically I would have been McCarthy's Enemy N.1

So far this thing is just vaporware. I learned long ago to be leary of flashy websites.

As for the rumored price, I certainly hope not. What would the point be in that? Where's the enticement? It gonna be very hard to take market share from a tried and trued product if it's priced the same. Thats an awful expensive leap of faith.

It gonna be very hard to take market share from a tried and trued product if it's priced the same. Thats an awful expensive leap of faith.

SRAM knows there will always be a few ready to make the leap (http://willyoumaketheleap.com).

Yeah, you measure force and throw in crankarm length with cadence, and you're in business. Not being able to measure upstroke isn't as attractive, but it should come out with calibration. At any rate, it's going to be much more precise than Polar or iBike, but the accuracy would be off. So that would make it just dandy for training, but not for comparison to other riders -- and that comparison should show up in the race results anyway. I understand the Minoura solution is probably just going to have one footbed sensor, but that would only affect accuracy, not precision.

So no updates that anyone's heard of?

Supposedly, Microsport is behind schedule and removed content from their website but are still aiming for a 2008 release. My guess is that we'll never hear from them again.

I wonder if cleat position would change the effective crankarm length.

Microsport is correct when they say little time is spent pulling up on the pedals. If Microsport put sensors in both shoes they would only be missing a small percent of the data compared to Ergomo only measuring 50%.

Left-right leg contribution to power output isn't constant so measuring only one leg will always affect precision. Remember, Coggan has said that the design and construction of powermeters that affects both accuracy and precision. It's no coincidence that the powermeters on the market that are accurate are also precise while the ones that aren't accurate are also not precise.

The only time you would have a precise but inaccurate powermeter is if you had a powermeter that had the potential to be accurate and precise but was out of calibration, like an SRM with the incorrect slope.

It's myth that all powermeters are precise or consistent. People just like to believe it because they can't accept the fact that they can't afford a better powermeter or that they wasted money on a bad powermeter and now have to spend even more money. It's a classic case of sour grapes when some people make a big deal out of what are extremely minor issues with SRMs.

Anyone hear anything new about the Minoura footbed solution?

seems seriously flawed like all footbed meters. They can neither tell what angle your foot is in relation to the crank nor how hard you are pulling up. As such it will have horrible accuracy and even worse encourage poor technique.

Further unlike waterrockets suggests you can't calibrate that out. Not only do different riders have completely different strokes which would require every owner to use a more accurate powermeter for calibrations but a single riders stroke changes dramatically based on how they are riding at the moment.

A footbed solution will always be the worst option after estimation. The amount of data missed is too great and much more variable even then what the ergomo misses.



Operating System:

Linux
That's enough to make me not intersted in it.

Why? Embedded linux not only works really really well but it also tends to lead to hackable devices that are not only fun but incredibly powerful compared to those using more propriatary solutions. Even if you don't find it to be a selling point it should at least be neutral.

Left-right leg contribution to power output isn't constant so measuring only one leg will always affect precision.
Can you explain this thought some more? Even if you have bad one-legged atrophy from a knee injury, doubling your power output in both legs would read as doubling your power on the meter.

Can you explain this thought some more? Even if you have bad one-legged atrophy from a knee injury, doubling your power output in both legs would read as doubling your power on the meter.

Good thread from BTR: http://biketechreview.com/phpBB2/viewtopic.php?t=1124&highlight=ergomo. Check out the studies in Kraig's links in particular.

Summary: there's evidence out there that L-R imbalance varies with cadence, fatigue, power output and position. Even worse, these imbalances are non-linear and idiosyncratic, so you can't correct in software.

Most of the Ergomo/PT statistical comparisons I've seen put it's accuracy on par with the iBike and Polar.

Why?

After my experience with Linux, for my part it would be because it makes it seem like it requires a lot of tweaking to get working. Of course, that was like 4 years ago. But it was enough of a PITA to keep me away in the intervening period.

Good thread from BTR: http://biketechreview.com/phpBB2/viewtopic.php?t=1124&highlight=ergomo. Check out the studies in Kraig's links in particular.

Summary: there's evidence out there that L-R imbalance varies with cadence, fatigue, power output and position. Even worse, these imbalances are non-linear and idiosyncratic, so you can't correct in software.

Most of the Ergomo/PT statistical comparisons I've seen put it's accuracy on par with the iBike and Polar.

I see. That makes sense. Back to lusting after a PowerTap. Well, lusting after an SRM, and planning for a PowerTap :)

After my experience with Linux, for my part it would be because it makes it seem like it requires a lot of tweaking to get working. Of course, that was like 4 years ago. But it was enough of a PITA to keep me away in the intervening period.

But this is a complete package; no tweaking of the OS needed by you. You might as well disregard using ATM's, cell-phones, or even ovens because their base OS may be problematic to get up and running on your own.

After my experience with Linux, for my part it would be because it makes it seem like it requires a lot of tweaking to get working. Of course, that was like 4 years ago. But it was enough of a PITA to keep me away in the intervening period.

I think you misunderstand what it being a linux OS means. You'll still be able to use it with your windows machine. The OS on the bike computer is Linux, just as are many cell phones and other handheld devices. You won't have to deal with the OS at all if you just want to use the built in features.

It doesn't actually measure torque (just acceleration, right?), which automatically lumps it in with iBike and the Polar, from my point of view.

Nothing measures tourque(except maybe the ergomo. You don't seem to understand how the various power meters work.

The powertap measures force at a specific point on the rear wheel and then computes power and torque from that combined with wheel speed and the location of the sensor.

This new one and the SRM measure force in the spider and compute with cadence and the sensors location.

The ergomo measures deflection of he bb spindle and computes power from that and cadence???

The polar measures force on the chain and computes power from that and chain speed.

That ****ty foot sensor thingy computes force on the bottom of the shoe and then computes with cadence and crnak length.

Finally the ibike, the one that stands out. It measures acceleration, speed, change in altitude and estimates the power needed to get get those.

I think you misunderstand what it being a linux OS means. You'll still be able to use it with your windows machine. The OS on the bike computer is Linux, just as are many cell phones and other handheld devices. You won't have to deal with the OS at all if you just want to use the built in features.

I understand that. I just have this hazy notion that one would have to be editing .conf files or something to get it working. I suppose since it comes with standard hardware, that's probably not the case. In fact, I love the idea of linux, and have been meaning to round up a spare computer to play with it.

One place I do like linux, though, is for web servers. I've done a fair amount of server-side development for sites on budget hosting, so I've become very familiar with linux in that context.

Anyway, /derail

Nothing measures tourque(except maybe the ergomo. You don't seem to understand how the various power meters work.

The powertap measures force at a specific point on the rear wheel and then computes power and torque from that combined with wheel speed and the location of the sensor.

This new one and the SRM measure force in the spider and compute with cadence and the sensors location.

The ergomo measures deflection of he bb spindle and computes power from that and cadence???

The polar measures force on the chain and computes power from that and chain speed.

That ****ty foot sensor thingy computes force on the bottom of the shoe and then computes with cadence and crnak length.

Finally the ibike, the one that stands out. It measures acceleration, speed, change in altitude and estimates the power needed to get get those.

None of the power meters measure force either, the main three measure displacement of something with known physical properties. The SRM/PT use strain gauges and the ergomo uses optical encoders, but all three are measuring the change in shape of something to allow the computer to calculate force or more importantly torque. The polar measures vibration, which allows it to estimate force.

I guess, you could take it a step further and say that the SRM/PT measure change in electrical resistance... but really they measure power. Good thing they are called power meters instead of force meters.

One place I do like linux, though, is for web servers. I've done a fair amount of server-side development for sites on budget hosting, so I've become very familiar with linux in that context.


I think the fact that anyone who works with computers,even web development, doesn't understand the concept of embedded operating systems is just scary. It shows the general lack of curiosity and big picture understanding that leads to so much of the piss poor and insecure code around.

None of the power meters measure force either, the main three measure displacement of something with known physical properties.

Which is how you measure force.

Which is how you measure force.

Which is how you measure torque... yet you said none of them measure torque?

OK, you guys have fun with this.

For the record, I do understand how they work, but thanks for informing me I don't!

I think the fact that anyone who works with computers,even web development, doesn't understand the concept of embedded operating systems is just scary. It shows the general lack of curiosity and big picture understanding that leads to so much of the piss poor and insecure code around.

That's just the tip of the iceberg.

Software development is my day job too. And I have little to no understanding of the concept of embedded operating systems. Or any desire to learn about them.

However, my code is amazingly good, and extremely secure. :)

The fact that the website can't spell "gauge" properly puts me off buying the product right from the get-go.

The fact that the website can't spell "gauge" properly puts me off buying the product right from the get-go.

People have strange reasons for bashing this product... "gage" is an acceptable spelling, not uncommon when referring to strain gauges.

The fact that the website can't spell "gauge" properly puts me off buying the product right from the get-go.

It's sad but "gage" has become an acceptable spelling. Look at entry #3:
http://www.thefreedictionary.com/gage