## Metrigear pedal spindle-based weenie-compatible power meter

Discuss light weight issues concerning road bikes & parts.
The Stig
Posts: 130
Joined: Wed Jun 04, 2008 4:19 am
youngs_modulus wrote:
The Stig wrote:It's attention to details that will set you apart. That's why that 3% matters...Let's say you and I make 300 watts of power, you at the pedals and me at the hub, what's your conclusion? Will that 3% advantage I have matter to you?

This is where you lost me. If you and I both make 300 watts of power, me at the pedals and you at the hub, then you're making ~7-10 watts more than me. If we weigh the same, you're going to beat me up the hill--you make more power than I do. Conversely, if we both make 300 watts where the tire meets the road, who cares whether my powermeter calls that 310 watts and yours calls it 300 watts? The race official is going to call it a dead heat no matter where we measure our power.

The Stig wrote:Maybe not, but it all depends on what perspective you are coming from...my 1 cent worth....

Oh hey--to each his own! Measure your power however you want...whoever trains more wins! Myself, I find posting to obscure web forums much easier than doing 3x3-minute interval sets at 105% of functional threshold power. Guess which I've spent more time on today. Seriously, this is a subject about which reasonable men can disagree. I was just curious about your thought process. Thanks for explaining.

Cheers,

Jason
Sempre Ferrari

The Stig
Posts: 130
Joined: Wed Jun 04, 2008 4:19 am
youngs_modulus wrote:
The Stig wrote:It's attention to details that will set you apart. That's why that 3% matters...Let's say you and I make 300 watts of power, you at the pedals and me at the hub, what's your conclusion? Will that 3% advantage I have matter to you?

This is where you lost me. If you and I both make 300 watts of power, me at the pedals and you at the hub, then you're making ~7-10 watts more than me. If we weigh the same, you're going to beat me up the hill--you make more power than I do. Conversely, if we both make 300 watts where the tire meets the road, who cares whether my powermeter calls that 310 watts and yours calls it 300 watts? The race official is going to call it a dead heat no matter where we measure our power.

The Stig wrote:Maybe not, but it all depends on what perspective you are coming from...my 1 cent worth....

Oh hey--to each his own! Measure your power however you want...whoever trains more wins! Myself, I find posting to obscure web forums much easier than doing 3x3-minute interval sets at 105% of functional threshold power. Guess which I've spent more time on today. Seriously, this is a subject about which reasonable men can disagree. I was just curious about your thought process. Thanks for explaining.

Cheers,

Jason

Yes...we can agree to disagree....

Regarding your statement of "whoever trains more wins!"....you overtrain, you loose....i think quality is more important than quantitiy...
Sempre Ferrari

slyboots
Posts: 445
Joined: Sun May 10, 2009 3:31 pm
Location: Russia, Moscow
Seems nice, small and clean, but we'll have to see how it performs.
Looks like it uses spindle deflection to measure the force applied, but how does it know if the force was applied at the end of the spindle, or closer to the crank? Depending on the point of application the same force will give different deflection.

Ypsylon
Posts: 1403
Joined: Wed May 24, 2006 6:25 pm

Does this work yet? Am I missing something?
"Nothing compares to the simple pleasures of a bike ride," said John F. Kennedy, a man who had the pleasure of Marilyn Monroe.

djconnel
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Location: San Francisco, CA
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I think you just email them and they add you. I've not received anything from them except specifically having to do with the pre-Interbike open house.

With regard to a sensitivity to where the force is applied to the pedal (outside versus inside), I got in a discussion with a Wattage contributor about this: at first I didn't think it was an issue, but then I drew the following diagram, which convinced me it may be an issue:

I asked Metrigear if the experiment has been conducted of comparing force to outside versus force to inside of pedal, but no response yet (actually I sent the question within the last hour).

djconnel
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I got a response. Yes, the pedal will account for the difference between force applied further out and closer to the crank arm. So rotating the foot in the shoe shouldn't affect the accuracy much.

If anyone here goes to Interbike (I won't be there unfortunately) try the experiment on the demo there...

clingenpeel
Posts: 424
Joined: Sun May 14, 2006 5:01 am
Location: Tennessee
Am I to understand the \$1000 for two pedals does not include a head unit? Will they be developing their own? I understand the SRM PCVI (which I believe is ANT+ compatible) does not work well (or at all) with other ANT+ power meters...thought I read something about someone trying to use an ANT+ PT hub with the SRM headunit, & it didn't work.

The price, weight, and simplicity of the metrigear system seems great (plus, I use speedplays)...the headunit would be the last piece of the puzzle for a truly great solution...I am not a fan of the new PT headunit or the GARMIN...I love my PCVI...I also have the original wireless PT headunit , which is fine, but not near as nice and user friendly as the PCVI...I thought I read the Wireless PT headhunits where upgradeable to ANT+...leaves me to wonder what headunit option folks will favor with this system if they don't offer their own.

djconnel
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The projected price I saw leaked to Wattage was \$899 for two pedals + the cost of the Speedplay pedals. In principle they could install in customer pedals, but the present strategy to keep it clean is to use only new pairs. No head unit: the goal is to work with any of the common ANT+ head units, at least for total power. Which are able to also provide L-R pedal balance is another story. Garmin, Specialized, and iBike are the units presently with the most interest in supporting new units: Quarq (who's known to be working on a head unit), Saris, and SRM would all prefer you use their power meters. iBike already has a lot going on. Specialized I'm suspecting will be fairly stripped down. So I'd put my money on Garmin being the best option: a feature-rich unit. Then there's Bontrager, which is reportedly doing a unit as well. I suspect that would also be a bit more stripped down, like Specialized.

But for total power, anything (perhaps excepting SRM) should work, I'd think.

tranzformer
Posts: 875
Joined: Mon Jan 21, 2008 10:36 pm
That isn't that bad of a price considering the wireless iBike runs around \$700 and a decent deal on a PT setup is probably \$700-800. This pedal based system seems ideal since it will let you use it with any frame (like the PT), and use it with any wheel (like the SRM). Once they come out and the kinks are worked out to the point that they are reliable, I will definitely be ordering a set. Just need to wait and see how things progress. I already started a savings fund for it.

Ypsylon
Posts: 1403
Joined: Wed May 24, 2006 6:25 pm
djconnel wrote:Which are able to also provide L-R pedal balance is another story.

Yep, that would be a very interesting feature and it would be a shame not too be able to use it. Then again it's only the icing on the cake, if the metrigear works as well as we all hope.

tranzformer wrote:That isn't that bad of a price considering the wireless iBike runs around \$700 and a decent deal on a PT setup is probably \$700-800. This pedal based system seems ideal since it will let you use it with any frame (like the PT), and use it with any wheel (like the SRM).

I'm not sure what takes longer, switching over a hollowtech II crank or two pedals, but it's definetly easier to carry around two pedals than an entire crank, if you have bikes in different places.

But I guess those are really only minor considerations just like the hub vs. crank/pedal location. It needs to work.
"Nothing compares to the simple pleasures of a bike ride," said John F. Kennedy, a man who had the pleasure of Marilyn Monroe.

djconnel
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Too bad there's no Qranium! A fully programmable portable ANT+ Sport receiver would solve the L/R problem. Some day. That fruit is too ripe.

The portability is a bit less than I'd thought. Just swapping pedals is easy enough. Having to also unscrew and transfer the battery/communication modules is a bit more effort. A few more seconds of work. It all adds up, though. Maybe Quarq wins the bike-to-bike transfer contest, though. I agree though for travel the pedal-only solution is better.

I hope they can do the Ti spindle. When you're spending close to \$1k for pedal spindles, they may as well be Ti.... the question's if the hole's big enough in those for the electronics.

Ypsylon
Posts: 1403
Joined: Wed May 24, 2006 6:25 pm
Well, I always leave my pedals on when switching around my SRM, you can get your choice of quickly changeable cranks but only take the pedals for the training camp so we have a clear winner in this department.

I'll need to get a discount if you want me to continue to promote this product.

I would also suggest you sell the product with a test and return option. If I could check it against my SRM, in which I trust, I would keep it if it's close enough. Just and idea, but otherwise I'd probably wait until I read the first reviews and you could speed up that process this way. Obviously I don't know how fast you can produce pedals and maybe they will sell like hot pie anyways and it will be hard to satisfy the demand rather than having to push them out.

And yep, the qranium would be great. Garmin keeps updating the firmware as well, but I suppose metrigear will have to gain quite a bit of influence before that happens, if there is no personal connection that could speed stuff up.

I`m a weenie, but somehow I'd prefer cromo axles and suppose those could be more precise. The electrics inside probably won't have a structural effect.
"Nothing compares to the simple pleasures of a bike ride," said John F. Kennedy, a man who had the pleasure of Marilyn Monroe.

bcheung
Posts: 841
Joined: Tue Mar 13, 2007 2:51 am
Location: Herndon, VA
gregclimbs wrote:Here is just some of it...

http://wattagetraining.com/forum/viewtopic.php?f=2&t=87

That is not a complete set of the information, but one of the ways to "optimize" the drivetrain. There are others. FWIW, the drag of the freehub on my zedtech sub9 has more friction than the rest of the drivetrain on my tt bike... spin the rear wheel on the stand and the cranks spin...

g

wow

what a heavy, HEAVY conversation!

Epic-o
Posts: 621
Joined: Tue Nov 20, 2007 7:18 pm
djconnel wrote:The projected price I saw leaked to Wattage was \$899 for two pedals + the cost of the Speedplay pedals. In principle they could install in customer pedals, but the present strategy to keep it clean is to use only new pairs. No head unit: the goal is to work with any of the common ANT+ head units, at least for total power. Which are able to also provide L-R pedal balance is another story. Garmin, Specialized, and iBike are the units presently with the most interest in supporting new units: Quarq (who's known to be working on a head unit), Saris, and SRM would all prefer you use their power meters. iBike already has a lot going on. Specialized I'm suspecting will be fairly stripped down. So I'd put my money on Garmin being the best option: a feature-rich unit. Then there's Bontrager, which is reportedly doing a unit as well. I suspect that would also be a bit more stripped down, like Specialized.

But for total power, anything (perhaps excepting SRM) should work, I'd think.

So...the only one pedal option that you commented will not be useable??

I want to know the accuracy comparison between two pedals vs. one pedal....

djconnel
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Well, for one thing, I don't work for MetriGear.... so no inside line on this stuff. I just attended the open house.

For comparing 1-pedal versus 2-pedal.... the firmware should handle this by realizing only one pedal is reporting and double the power from that pedal for calculating average power over the stroke. With two pedals, one is the master and the other the slave, so the slave reports data to the master which then communicates with the head unit. But either pedal can assume the role of master if the other is missing.

So to check the validity of this assumption, I'd ride with, for example, a PowerTap or iBike or Quarq (this might require two head units) and ride with one pedal "live" the other "dead" (for example, remove the battery), then ride with both pedals live, and plot PowerTap/iBike/Quarq power versus Vector power in each case, then ride again with one pedal live but the other pedal. With two pedals, the agreement should be quite good. With one pedal, there will likely be more scatter, and there will be an additional bias based on average left/right pedal imbalance.

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