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

180, hub only, and very limited numbers. I bought most of them.

10 of them on eBay that Paligap had found behind the sofa...should have got more than 1.

I sold mine recently for roughly what I paid for it, which is kinda crazy.

Anyone want any White Industries sprockets?

Yeah, the UK service centre's stock take sale from a few years ago does not a current price make.

Sorry, I should have been clearer.

It's not track, G3 11 speed Shimano and I'm selling, or rather my friend is to fund an Aerocoach disc.

Ah ok - Let me know when it's sold and I'll try and flog mine for a similar price then! :)

Stay tuned to TTF!

Might try a punt now, but I fancy you'll both get a better price in the Spring.

Werent track powertaps on sale for like 150 a couple years ago?

£189.99, and if you own a time machine feel free to go back and get one, but as @umop3pisdn says, the value now is related to what they currently sell for, not what @Scilly.Suffolk may have paid.

No bigger joy than reading happy ending bug finding #powerpod https://ibikeforum.com/viewtopic.php?f=93&t=3748

I bought the other.

It's still in the box...

@scilly.suffolk - if you want it, it's your's for whatever I paid less 10% because it's a few years old.

It's 24 hole, which is why I haven't used it.

On that note - what track crank-based power meter?

I understand that p2m don't do them any more.

Thanks for the offer, much appreciated!

But I "don't need an accountant to tell me how poor I am".

I'm interested since @Scilly.Suffolk has passed on it. I've sent you a PM.

So for me it looks like a circa 7% difference in FTP measured at crank vs. hub. Sound about right? Maybe I should clean my chain...

hmm - sounds a bit high.

Although need to take into account error ranges for both devices. Typically + - 2 % for crank and + - 1% for powertap iirc, so that could account for %3 of that (or it could be 10%)

Do this:
http://www.timetriallingforum.co.uk/index.php?/topic/124605-52t-use-track-chainring/

Unless you need the low Q factor...

Thanks @danb - Will re-test once I fit a new chain in the next couple of weeks.

The USE chainring means you can use road cranks on a track bike, but it doesn't solve the problem of the auto-zeroing giving bad calibration results on a fixed gear bike. You need some way to turn off the auto-zeroing, which AFAIK was the only difference between the normal P2M spider and the track one - the track one had auto-zeroing disabled, which you can't do with the normal one.

These days I believe it's SRM or nothing for track crank-based PMs.

Infocrank are supposed to be bringing out a track PM

You need some way to turn off the auto-zeroing, which AFAIK was the only difference between the normal P2M spider and the track one - the track one had auto-zeroing disabled, which you can't do with the normal one.

Isn't auto-zero a feature of the head unit, not the PM? Or does P2M do some re-calibration of itself independently of the head unit that you need to turn off for tark?

Ah, good point.

I'm pretty sure I saw the ability to turn off the auto-zero when I looked at the settings on my Quarq the other day.

Isn't auto-zero a feature of the head unit, not the PM? Or does P2M do some re-calibration of itself independently of the head unit that you need to turn off for tark?

Nope, it's a feature of the PM. You can use a head unit to trigger a zero calibration, but the auto-zero stuff is done by the PM itself. The conditions in which the PM will carry out an auto-zero are particular to each, and they'll do it themselves. For example, with a Powertap track hub you need to turn off auto-zeroing. You can do that with a Joule GPS cycle computer, and once you've changed that setting you can use any head unit you like - the autozeroing will stay switched off in the hub's firmware.

I'm pretty sure I saw the ability to turn off the auto-zero when I looked at the settings on my Quarq the other day.

Quite possibly, it's a while since I last had to play with Qalvin. I've never really understood why it isn't offered as an option universally. The extra code would be minimal, I would've thought.

Goes some way to explain why Garmin removed the option shut down auto-zero accross all of its devices regardless of PM type, I guess.

Please could you explain why this might be an issue for use in a velodrome or in a fixed tt situation with P2M? Shouldn't the p2m auto zero only when there is 2secs of no power which is unlikely to happen on a fixed? thanks