All of them today are requiring both pods. Technically though, most of these companies manufacture both pods identically (Garmin, Polar, Brim, Rotor) from a hardware standpoint and simply assign them a unique value/side upon leaving factory. In the case of Vector, that actually happens dynamically each installation based on the pedal utilized.

That said, all of these companies have also said that if market conditions demand they could go single-sided. We've seen that with ROTOR recently (albeit with dorked up pricing), and I think we'll likely see it with others.

For companies just entering the market though it doesn't really make much business sense. So taking PowerBeat, they'll sell a gazillion units at $499 (assuming it's accurate, etc...). It would make good business sense for them to meet demand, then once they can do that they can look at halfies. Same goes for Brim, etc... Since the actual cost of goods on some of these is relatively low (for a second pod), that allows them to recoup much of their long-tail initial costs.

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My tiny little slice of the internets: dcrainmaker.com

I work with strain gauges for a living. Let me tell everyone here that bonding strain gauges to a surface is not the most straightforward as it sounds.

1) clean surface- I bond strain gauges to human bone and it is extremely difficult to get a clean surface here. Engineering materials are easier but you have to sand, clean with acetone, and make sure you dont touch the gauge surface. AT ALL. If your glue layer is too thick, your readings will be out as well. I use dental tools and a magnifier to help me here- I realise their sensor unit is actually bigger, but still tells you the level of precision and cleanliness you need.

2) Im skeptical about their claims of being compatible with every crank. Their sensor looks like it needs a flat surface to bond, so cranks with curved edges-ala campy- may be out.

3) surface properties- what a strain gauge essentially measures is the deformation of the surface layer. Which means that if your crank has a chip in the lacquer layer and you mount it there you'd get slightly different readings than if you mounted it on the lacquer. What this also means that the sensor is 'one use only'- I highly doubt you could transfer it from crank to crank. Any damage from riding/transport and you'd need a new sensor- given the location and type of manufacture, this is probably going to be reasonably often. How much would a replacemnt sensor cost? 60usd? A strain rosette costs about 20usd from my suppliers, so you do the math. Add in the man hour cost of any repairs and re-mounting you need to do.

4) misalignment errors- this is one where I dont know how they're going to get around. It is incredibly easy to misalign a strain gauge. I highly suspect. They'd be using rosettes, rather than uniaxial gauges because theres no way an average Joe will stick on a uniaxial gauge with any degree of accuracy on their first try. To mount rosettes I actually very lightly score the location with a scalpel blade - thats the degree that I need to get it to. Even with a rosette, the chances of misalignment are still quite high, especially if you're not used to precision work. I dont know how robust their algorithm is to misalignment, bur my guess is going to be: not enough for the mass market.

5) damage- strain gauges are pretty sensitive to getting damaged- they are tiny things with connecting wires about 0.5mm thick. Even protected, there are chances things can go wrong. Especially for such an exposed unit.

My opinion? I'd be curious to try it, simply because ive done similar things so it wouldnt be that difficult. But you'd have to pull the cranks and chainrings, and have a reasonably clean environment to do this properly. Ideally you'd want to have a good to pro level bike shop help you with this- similar in concept to how pioneer is doing this. I really hope it works, and maybe they're working with better equipment than i'm used to, but I'm skeptical. Could it be 'good enough'? Probably. But for all that trouble, good enough won't cut it. Pay the slight extra for a stages and save yourself alot if trouble.

From reading their material, I don't think they'll be asking the user to do the actual strain gauge bonding as you describe. Instead, that is already done to a flexible member (don't know the exact configuration of that, but it will be interesting to see) which is then in turn attached to the crankarm. It will be interesting to see what, if any, user calibration is required and how stable that mounting is over time.

You know...at that price point, PT hubs sure look pretty darned nice still...

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http://bikeblather.blogspot.com/

jut curious where you read/heard this statement from SRM?

Chuckle chuckle. Ok enough juvenile humor, carry on carry on...

I've heard similar from them at Interbike...along with the statement that their true focus is on the pro riders, and if you want to be like a pro rider, then that's going to cost you (or words to that effect)

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http://bikeblather.blogspot.com/

Is this essentially the flo of PM's? For the "budget" athlete, great alternative?

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@brooksdoughtie
USAT-L2,Y&J; USAC-L2
http://www.aomultisport.com

No. The "Flo of PMs" would be a Flo PM ;-)

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http://bikeblather.blogspot.com/

I'm up for anything that gives me an affordable way to out a PM on Helium. Chorus group and Ksyrium SLR wheels don't give me many options.

Vector and Power2max are both too expensive. Used quarq would work, but putting that crank on the campy group seems wrong.

Though this does look a bit delicate to me.

I'll admit I didn't read the whole thread. DCRainmaker reviewed a $500 power meter here http://www.dcrainmaker.com/...their-powerbeat.html , Is that the same one?

Yes that's the same one, but it's not really a review, it's more like a preview.

Be patient fellow cyclists. Jon and Chris(Flo Cycling) are developing a power meter for the rest of us. There is speculation that a prototype is nearing completion. I don't expect to have one in hand until next year, however. Maybe they will have it ready for Interbike.
Joe

> Maybe they will have it ready for Interbike.

And we all know that once you show a working power meter at Interbike, it's all smooth sailing from there!

I expect that Stages should be able to easily produce a L-R version of their PM pretty easily. They should jump in this game as they have a product that is much more proven than Vector, or other unknown products.

I agree with you. A bluetooth capable, left/right power meter from Stages would be fantastic!

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Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

Where would Stages fit their sensor on the drive side?

Exactly.

Meanwhile, some of us have been benefitting from power data since before the turn of the millennium...

The inaccuracies that would introduce into your power data could possibly be very big. you're trying to measure the the strain at the crank through 4 surface layers 1) crank to glue boundary 2) glue to member boundary 3) member to cyanocryolate/epoxy boundary 4) cyanocryolate/epoxy boundary to strain rosette. I know from my work that a layer of cyanocryolate between rosettes and the surfaces I work with introduce +/- 2% error into strain readings, which is still acceptable. over 4 different surface layers? how big would your error be? maybe 10%?

Could you make it work? with ALOT of testing, I'm sure as heck you could implement an algorithm to take that into account. I shudder to think about the poor sod who's got to take viscoelasticities of any glue/epoxy you're working with and different stress transmissions across those layers. At least pioneer has slightly better, potentially workable system for a custom installed power meter. I don't really see how this is going to work.

like I said, it may be POSSIBLY 'good enough', just like stages is with NDS power only. for many people. but I'm skeptical and I honestly think at that price point and the level of accuracy you'd get, coupled with all the possbilities of things going wrong, a powertap or stages would be slightly more expensive but still be way superior in the long run.

All for the price of a Quarq, or more than a Power2Max...nah I'm good

is srm giggling somewhere

http://www.behindthebarriers.tv/...-meter-factory-tour/

If you look at what stages has to do to get accurate calibration, slope, etc for each individual unit. I find it hard to believe that a unit bonded by the user will be accurate enough to train effectively with. But the whole industry has a tendency to cause skepticism based on its track record.

Their Patent has a leaf spring to whcih the strain gauges are attached to. so they are not measuring DIRECT strain. I'm very interested to see how this works or what their algorithm is doing.

Quote:

bluetooth capable

I'm genuinely curious. Why is bluetooth a primary requirement? Are you using an iPhone or something like that as a head unit?