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

Ace, thanks Sainos. That's really helpful. I've done all that when shifting the unit around except the battery removal.... i presume it's been under-reading all this time then :-)

apparently this supposed to be done every ride

sounds like a royal PITA.

a lot of the other power meter instructions do stipulate some fairly complicated pre ride criteria, but yes it does take a couple of minutes to get things set up properly, which I believe was Garmin-Cannondales excuse for not using them...

then again it probably takes me 15 minutes to get all my gear on to go for a bike ride, so in the general context of things 2 minutes isn't where I can make the most use of my training time!

yes, id presume that too, I went through a phase where I didn't remove the batteries and it was under reading chronically, probably to about the tune of 60w based on a time trial I did at the time. was tearing my hair out trying to work out what had happened to my legs!

I'll be using an Edge 500. This worries me a little as its pre Vector. Wonder if it'll be worth grabbing a 510 at some point.

I was joking about the under-reading, but you've just given me a glimmer of hope!

I also have dual sided vectors.

I had the first version where you clamp the pod into place with the pedal axle, and they essentially worked perfectly for a year swapping between bikes with very few issues. Then the pod snapped (at c.10newtons of force) so I got them repaired under warranty and most (although not all) of the parts were upgraded to the V2 version.

In the 6 months since the repair I've ridden very little so it's hard to give an accurate impression. Initially it was almost impossible to get them to pair, but since the initial teething problems I've not really had any difficulties. Battery drainage seems to be worse on the V2s and I seem to have a different pedal balance than previously (which is somewhat worrying) but broadly speaking I'm pretty positive about them and no real regrets.

That said, if I had to buy new today I'd almost certainly go with power2max.

I should also add that I use them with a 910xt. This means that (a) I only get the 'conventional' power metrics and not any of the fancy pedal dynamics stuff (whether or not it's of any use) and (b) I have no option for setting angles etc. I just run a static calibration before each ride. My understanding is that everything else is automatic in the 910xt, but it does occasionally worry me that I can't manually reset or validate any of the angle/calibration settings etc.

I knew you were, but just in case you don't believe me....

the bottom image is the same section of road where you cna see, 10th May, power meter working fine, 25th July, my heart rate was 10bpm higher, I was going 2kph faster, but doing 64w less apparently....

this alone isn't perfectly conclusive, and there were other factors at play, but its generally consistent with the other data I was seeing at the time...

the top image was a series of 10 mile time trails, the red are, I believe correct, the top seems to be way down on power for the HR and resulting speed...

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I'm looking to sell my power2max rival chainset (compact 170mm arms) with 700m miles on them. A colleague is interested in buying them but I'm struggling to put a value on them?

Anybody help?

50 dorra

classic or type-s?

I'll have a think...

classic

£350-400 seems to be typical for classic.

thanks for your help, most useful

Does anyone use Stravistix? I'm trying to work out the relevance of the 'Weighted w/kg' and what this means in relation to FTP. My FTP (last tested a while ago) puts me at a rubs 240W or 3.2w/kg, but according to Stravistix, my last two rides (5 hour and 2.5 hour) have been a slightly better (considering I'm not 'training') 3.5w/kg. That discrepancy doesn't seem to make sense to me as surely I shouldn't be able to average way above my FTP for 5/2.5 hours.

Today's club run was pretty fast, but according to Strava it was 105% intensity. Over 2.5 hours. This suggests to me that my FTP is too low, as I felt fine at the end of it.

I know I have to retest my FTP soon, but for future - what is that Stravistix figure actually showing me?

First picture is 5 hour ride on Thursday, second is today's 2.5 hour club run.

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according to Stravistix That discrepancy doesn't seem to make sense to me

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Any Strava or plurals of Strava chat should be in the Strava thread where 'analysis' of randomly generated imaginary power values belong.

This useless reply bought to you by

DrinkBeerTrainingSystems™

As I understand it, "weighted average power" is strava's equivalent of Normalised Power (NP).

Essentially, time spent working hard on the ride (climbs, time on the front etc.) takes more out of you than equivalent amounts of time taking it easy (in the group, descending etc.). For example consider two rides: a 20 minute effort where you ride for 5min@220w, 10min@260w, 5min@220w, and a 20minute effort where you hold a steady 240w for the entire 20minutes. Both rides would have the same "average power" but the first effort would feel considerably harder. This means that average power can be a pretty unreliable metric for how hard you were working.

To try and get around this, NP (or strava's weighted average power) use an equation that gives more weight to hard efforts than easy efforts.

In a group ride you might expect to have a lot of 'down time' interspersed with periods of higher intensity an NP of 290 is essentially telling you what the equivalent power you would have to have held over the entire workout to achieve the same 'effort', even though your actual average power is likely to be far lower.

For these reasons NP is usually a better measure of effort (I use it for calculating my FTP from TTs), and in your case may suggest that your FTP is a bit low. However, it's not a perfect metric and if you look at how the equation works you can see that it is possible to game NP with a few short and hard efforts that artificially raise NP. For most people, the only effective way of knowing what your FTP actually is, is to test it.

Ah, ok thank you. Training peaks gives me 242w NP for the second ride, so somewhere in the middle of Strava and Stravistix. It was a social ride but the last 10 miles was a fairly hard chaingang so that will have pushed it up.

I really ought to do an FTP test but I hate doing them inside and it's hard to find somewhere long enough to do one around here. You want a gradual, long, hill - right?

Ftp outside is easy, just enter a 25M TT

Bleurgh. Thinking about it, the TT circuits around here are pretty well mapped. Just need to get out and have a spin round. The idea of an actual organised one terrifies me, it took me long enough to join a club.

The idea of an actual organised one terrifies me, it took me long enough to join a club.

There's no substitute for pinning a number on to find out what you're really capable of. If you're not going to race, why are you even measuring power? You might as well just enjoy the scenery, it's more pleasant and healthier.

Coz I like seeing that I'm improving, basically. Isn't it the same reason that everyone uses Strava? It's not as if power meters are expensive any more, so I don't see a good reason not to use one really.

I do have vague notions of racing this year, but at the moment they are just notions. I'll probably do some track league, but I'm quite happy just doing chain gangs/SQTs/club runs as they keep me sane and keep the weight off.

Isn't it the same reason that everyone uses Strava?

I have no idea why people use Strava. If I were cycling just for the sake of my mental and physical health, I wouldn't be measuring anything.