Power Meters / Powermeters (SRM, Powertap, Quarq, Ergomo, Vector, Stages, power2max, P2M, 4iii, InPower, Cinch)

could be depending on chainrings age ?

~2250km apparently. In good nick, used but loads of life left.

DM me.

Anyone got any CR2450n batteries for Gen 1 P2ms that they do not need kicking around?

What would be a fair price for a quarq elsa rs, with 52t dura ace matching ring, and 53t ultegra non matching ring, and 39t ultegra inner.

Good condition just don't think I'll ever be on a road bike enough to warrant it. I've had it a while and still not used it, and I've forgotten what I paid for it.

What sort of price do these things go for?

My Rotor Inpower reads 4% lower than @cjr 's Garmin Vector 3, and my Kickr (once it's warmed up). I can adjust the crank length in my head unit, which should affect the relative power displayed - should I make the cranks longer or shorter to give 4% higher reading?

Or just complain to them? They say it should be +/-2 %.

It could still be. Don't forget that the other devices you are comparing to likely have similar accuracy.

If they are +2 and the rotor -2 then there is your 4%

@dbr Can you do a static torque test? That should tell you if they are out substantially.

The difference is consistent - always 4%. Without lab testing you couldn't claim the Vectors or the Rotor were telling the truth... maybe they're both wrong. Either way it doesn't really matter, I just want it to read the same as my Kickr.

Also, the Inpower was second hand on ebay for a steal, I doubt Rotor would be much help.

Fair enough.

If its you're only pm just leave it at 4% lower. Absolute numbere dont matter, just relative.

I'm not sure cranknlength alteration would give 4 anyway.

Dan's suggestion of static torque is sensible.

I remember reading both DCR and GPLlama having the same issue of single digit % off, in their case too high.

Would expect Rotor to have a fix, see what they say, or just redo with a few crank lengths. I remember forgetting to reset my Vectors with the right crank length and busting out great FTP tests only to brought back to earth...

Or you could buy my P2M NGeco which reads 1.5-2% higher* than my Tacx Neo (which is accurate to 0.5% apparently) :)

*Which is in line with what I would expect due to drivetrain losses

FYI, changing crank length on my Elemnt Bolt didn't seem to make a difference and kept reverting to 172.5mm anyway.

Thanks to cjr's pedals, I know my L/R balance is a nice even 50/50. The Rotor cranks are left-only so using their crunky software I've set the balance to 48/52, giving me a 4% overall increase in power. It now lines up nicely with the Garmin pedals and the Kickr (once it's had a good 40 mins to warm up).

G3 hubs. Does anyone near me (Brixton / sydenham) have the tool to help me change the battery that I could borrow? Ta.

Yeah. Ealing.

Oh, you probably mean 'near' in the normal sense of the word.

Where you work?

Fitzrovia/Soho at the mo'mo'

Right
You in tmrw?

I wasn't going to be. It's chucking it down.

There's this thing called public transport?

Yeah, I used that the other day. What a ballache.
I'd rather spend those 3 hours of my life doing something useful.
Also WFH is free. Also I have to vote tomorrow and unlike my Clever Country I have to do that near home. I'll be at home tonight, ride over and I can even give you a new battery.

I'm on dad life now. next week.

Where do you live? Maybe I could drop it off?

Sydenham SE26.
Let me see if I can pop off using inner tube trick..

I only do mine up finger tight so I don't have to use the stupid fucking Powertwat tools.