My hypothetical scenario was more centered on the SRM part. "Shure, we'll try your electronic pedal but we'll keep the SRM's 'til we know they work."


Garmin wanted to tout the new, modern PM. The team wanted reliable power data. Black tape and returned pedals...


I still think the delayed introduction is related to the results of many Vectors facing the real world (and their pesky SRMs) at the same time.


Six sigma, anyone?

I take it Robert is a 'small name'... ;-)

And yet, Robert is the Gauss of Wattage...

Nice catch.

BUT, look here:

http://gbr.garmin.com/...cycling/cycling.html

At 2:36 and 6:35, you can see that team bikes at their winter camp in Spain are equipped with Garmin Vector pedals and the crank-attached pods.

Also, at 1:57, Garmin pedal on a bike sans the SRM.

mm

So is the only problem is if you are standing up? It seems like using a power meter would be most helpful training on the hills. Yet you're out of the saddle on the hills. Couldn't you program your weight into the computer to factor in weight so power would still be accurate while standing?

more bad news for all you Garmin PM fanboys:

guess what a rider on the Chipotle Development Team is using for PM? Note, the guy is actually using a Garmin branded pedal, but no sensors on the crankarms

As others have noted - it doesn't matter if you are standing and pedaling.... Yes your weight will assist in exerting more force on the pedals which will (in the short term at least) increase the power to the drive train of the bike. That is what the vector as well as ANY other power meter attached at the crank or hub would measure - as they should.

And that's the error in the reasoning. The pressure on the trailing pedal as yo're standing works against the force on the downward pedal. So if you are pushing with 80% of your weight on your down leg and 10% on the left (assume 10% on bars) then the drive power (ignoring drivetrain losses) is a function of 70% of your weight. If that changes to 75:15 then it's down to 60%. The pedal systems have this issue, the crank / chain/hub systems don't have this as they read after this effect has occred in the crank. The ergomo only read from the left crank, so different issues.

Of course you cold suggest that as you are still doing the work, then it's an advantage to see that total energy figure, including the counter productive work, to allow you to pace to your total energy reserves. Not convinced, but there's an arguement that could be constructed around this.

I think you might want to rethink this opinion that the pedal-based PMs will somehow read differently than other PMs when the rider is standing...you may be misunderstanding how the pedal-based PMs combine the output from both sides to get the net "effective" power.

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http://bikeblather.blogspot.com/

Tom - I was responding to the bit I highlighted in the post above whish is factually / technically incorrect.

Unless I'm mistaken, then there are comments in this thread and elsewhere where not only the gen pop, but also Garmin have stated that the calculation of the effect of standing is very hard to calculate. In fact reading between the words in the statement then they appear not to be attempting to calculate the true power, but use an algorithm to translate the raw readings into an estimated power value (actually 2 power values, left and right). Not saying there is anything wrong with this, but my comment above stated that 1) crank/chain/hub meters don't have a problem with negative effort; and 2) pedal based systems do need to make some form of calculation / estimation of useful power based on raw readings that include counter productive power.

I don't buy the posted accuracy rates at all. i am interested in the pedal based power meter, but will wait for real world feedback before i make the investment.

every power meter on earth does that.
an SRM doesn't directly measure power, a fancy automotive dynanometer doesn't directly measure power. you can't.

you can measure how many volts are coming out of a strain gauge, which lets you estimate how far it bent, with which you can estimate how much a crank/pedal/hub spinder bent. you then use algorithms to estimate the torque

then you get some readings on how fast stuff is spinning around, and then you use that and the torque your estimated to estimate power.

in all cases you will have to account for various 'weird' situations.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Just added back in the bit from my original quote.
Ok, but what 'wierd' situations are you needing to account with hub or crank systems? And is standing to pedal really classed as 'wierd'?

I get that people want a system that allows them to use different length cranks between road and TT bikes. And if it was possible to add to a spin bike in a gym, then I could really see that as a plus as I tend to do a fair few spin classes over winter to mix it up. But there seems a lot of 'emperor's new clothes said about the pedal meters which doesn't always seem to be tempered with the disadvantages. Overall, people should choose the system that best matches their needs - strong where they need it most, weak where it's less of an issue.

any updates on when its coming out?

June 2010

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Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook

Standing might introduce odd readings in the crank based systems. Bumps in the road might introduce strange reading in any system, wheel flex/hub flex in corners and so on.

The pedal system may be a bit more complex, at the very least you have TWO devices communicating wirelessly instead of one, which is perhaps insane.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

All they need to do is determine the orientation of the pedal spindle with respect to the crank arm (for the Look/Polar pedals this requires and specific orientation upon installation, the Vectors will determine orientation using the gravity vector) and then only calculate the torque that moves the cranks "forward". That only requires keeping track of the "sign" of the deflection.

My suspicion is you're "over-thinking" this...

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http://bikeblather.blogspot.com/

LOL

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Eliot
blog thing - strava thing

Surely that has to be pink for a ST thread. Given the huge debates of the devastating aero effect of a 5mm bit of brake cable on a bike frame carrying a 80kg rider.... ;-)

You may well be right. I'm happy to admit I may be over thinking, I would suggest some may be under thinking pedal based a little though...

endless debates can by caused both by over and under thinking ;)

I don't think pedals are going to present any challenges astronomically harder to overcome than cranks or wheel hubs or bottom brackets.

all of these types of power meters took time to get right. it isn't easy, period. which is why it is pretty costly to obtain one.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Yep agree the issues raised with the separate measurement of of left and right leg to derive a total power output is indeed a little trickier than a crank or hub based system, but i don't get the gist of why standing presents any complication over what happens when you are seated and pedaling. When you are seated the weight of your trailing leg is also resisting in a small way the downstroke of the other leg. Hence I just don't get the standing thing - sorry it is a red herring!

fixed

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The entire event (IM) is like "death by 1000 cuts" and the best race is minimizing all those cuts and losing less blood than the other guy. - Dev

I'm not convinced you aren't "under-thinking" this, Tom. It isn't just about the sign being + or -, there is surely an issue with the direction of the force relative to the crank arm. I can see how the Look/Polar system can handle it, as it must be installed with a specific orientation, so I assume they have an arrangement of strain gauges that lets them work out the force perpendicular to the crank arm. But I'm struggling to see what arrangement of strain gauges will allow the Vector to resolve the force in the same way. So I expect that the problem with standing isn't the sign of the contribution from each leg, but the fact that you will get significant force applied that isn't perpendicular to the crank arm, and I think they may well have issues in working out how much of the total applied force is in a productive direction, regardless of sign.

just toss a g meter in there!
does it have one anyway?

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Steve,

I would imagine that the first thing that will occur once the Garmin pedals are installed is that the system quickly "learns" the pedal's orientation to the crank and retains it until the next new installation. Developing the algorithm might be difficult but I don't see it as impossibly so.

YMMV,

Hugh

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Genetics load the gun, lifestyle pulls the trigger.

Knowing the orientation of the pedal at all times doesn't solve the problem, you still need some way of resolving the measured force into radial and tangential components. It isn't clear to me how they can do this, whereas it's much easier to see how the Look/Polar pedals can do it with their fixed alignment.