New powermeter rumours

[jo.k]

For the P2M users, battery life will be significantly shorter with a CR2450 cell compared to the (specified) CR2450n. The 2450n has a slightly different geometry - the part with reduced diameter is deeper. I was unaware of this, and kept installing 2450s that only lasted a few months. The 2450n will last close to a year I reckon.

[ChrisSnyder]

I am wondering how much those replacement chainrings for the C1 are going to be.

[Squint]

The performance gain is that they will work a longer time. If the pedal suppose to work 60hrs with a AAA 750mAh battery, can you imagine how long it would work with a CR2032 220mAh or CR2450 550mAh battery? Surely less and not enough.

That alone is probably the main and only real reason for the AAA battery. It was marketing that suggests they're easier to buy.

Don't forget that the coin cells are 3V vs. the 1.5V of the AAA. That closes the gap a bit.

[rma]

Any news on the Rotor Inpower? Really interested in these PM.
Also, has anyone seen a detailed review of Rotor Power?

[mattjevans]

Any news on the Rotor Inpower? Really interested in these PM.

What is this - I seem to have missed it

[Mario Jr.]

Wait a couple of weeks

[mattjevans]

Went back quite a few pages and found comments on it being possibly spindle based (and the very strange claim that this would make it left-only measurement)

[ITTY]

I still don't understand how a spindle based system could work. If you measure strain at the spindle, you are measuring the difference (in stress) between the two sides, but that wouldn't be able to distinguish resistance between the chainrings and right crank, since they are attached by the spider. So yes, in essence it would be one sided, but I can't imagine it being very accurate.

Edit: Actually, I suppose that is the same concept as stages or any other left side PM, since they can't tell a difference between right crank and spider either. I still like the spider measurement location the best, since it is measuring ONLY the power being put into the drivetrain (by both legs).

[zirxo]

https://twitter.com/dcrainmakerblog/sta ... 2177513472
4iiii seems to be in production for real now.

[jeffy]

I feel for Stages. They will have to drop prices if 4iiii has comparable performance.

I wonder if double sided (such as p2m) will feel pressure to reduce prices.

[stuka666]

And carbon cranks with 4iii, release in the near future?

[eric]

I hope so. If and when it works on carbon it could be the new light weight PM option.

[jeffy]

if stages couldn't get crank based strain gauges to work reliably on carbon, my hugely ignorant inner engineer would be very skeptical about any claims by 4iiii that they could.

[mattjevans]

I still don't understand how a spindle based system could work. If you measure strain at the spindle, you are measuring the difference (in stress) between the two sides, but that wouldn't be able to distinguish resistance between the chainrings and right crank, since they are attached by the spider. So yes, in essence it would be one sided, but I can't imagine it being very accurate.

Edit: Actually, I suppose that is the same concept as stages or any other left side PM, since they can't tell a difference between right crank and spider either. I still like the spider measurement location the best, since it is measuring ONLY the power being put into the drivetrain (by both legs).

I'm a bit puzzled too, am assuming it measures twist forces, so would have thought it was very sensitive to the "negative" force the upwards moving leg generates. In theory I suppose a perfect "spinner" (though I bet in practice there are no such people) might generate equal down and up force on opposite sides and no (net) twist force on the spindle

[nathanong87]

just got myself a stages.... and noticed insane power drops indoors. Is this thing more finicky than lets say....a quarq for wifi interference? it was comically bad.