Which power meter – Stages or Power2Max?

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  • Which power meter – Stages or Power2Max?
  • LS
    Member

    Contacts anyone?

    For you – European centre in the Czech Republic. Cheaper and quicker than Paligap here, even if you’re based in the UK!

    How do they die out of interest?

    Eventually the torque tube decides to either be very unreliable (not holding a constant zero-torque figure) or just go pop completely. Thankfully it’s not like a gradual drift, you can tell instantly. I’ve had a few over the years but in Feb, of the three I had at the time, two went together. One was fixed for free (a well out of warranty SL, but water creeps past the carbon bits and is a known issue so fixed gratis) and the other I had to write off. The SL was sold to part-fund the P2M, which was costly for what I need (180mm cranks so limited options).
    My final PT is an old Pro+ which although fine at the moment, is 5 years old and won’t last forever.

    LS
    Member

    The new G3 Powertaps are a step down in quality – I’ve seen several die within a couple of months, and my missus had one that was goosed when we got it out of the box. I won’t be going anywhere near them.

    carbonfiend – Member
    This is a long read but if you stick with it is really helpful http://www.dcrainmaker.com/2013/06/stages-review-update.html

    bob_summers – Member
    I’ve read the in depth reviews on DCRainmaker but none the wiser really.

    DanW
    Member

    ^ When I queried this I was told they are not allowed to ship to the UK… I’m sure someone in the EU must have not got the memo though 😀

    TiRed
    Member

    Been an early adopter of Stages, having brought one back from the US a month after launch. A little more reasonably priced Ultegra. After breaking two, it gives me good reproducible readings with good battery life. I don’t really care about L/R balance, but riding fixed wheel and sitting on a Watt Bike occasionally shows my balance is fine. My FTP has increased a lot over the past 12 months, but just comparing NP with others in a race tends to give consistent results for similar efforts.

    I’m a happy customer and would recommend again. If they were £400, I’d have one on every bike I own.

    I also have a PowerCal. Scoff all you like, but the NP readings have been curiously similar to the Stages, so I use that rather than swap cranks.

    Premier Icon mrblobby
    Subscriber

    I also have a PowerCal. Scoff all you like, but the NP readings have been curiously similar to the Stages, so I use that rather than swap cranks.

    Probably not a bad bet if you just want an NP and to work out a TSS for a ride, especially given the price. I may check it out. Need a new HR strap anyway. Would it be any different to the values something like training peaks works out based on your HR data though?

    DanW
    Member

    I also have a PowerCal. Scoff all you like, but the NP readings have been curiously similar to the Stages, so I use that rather than swap cranks.

    Depends on the rides. I’d have thought that the more gradual the changes in intensity, the more HR will reflect the effort. There will still be some errors and things you can’t escape from with HR but as you say, in a lot of circumstances HR derived measures of effort aren’t too bad at all. NP is itself is a measure not suited to very variable efforts (MTB particularly inappropriate due to a large number of very short, very high efforts) yet people like to blindly apply NP/ IF/ TSS/ etc to everything without any account for the signals measured or how the analysis works…

    barrykellett
    Member

    I’ve used hrTSS on non powermeter equipped rides and as the guys have said, its accurate enough for a TSS figure to keep your data up to date.

    It won’t cope well with a couple of sets of anaerobic intervals but for a long steady tempo ride or 2×20 it won’t be far off.

    pitchpro2011
    Member

    Durian rider does a very good comparison video on these and the guy rides ALOT
    Stages Cycling Power Meter Review #2: http://youtu.be/4QR-VC1DAVI

    LS
    Member

    I’ve used hrTSS on non powermeter equipped rides and as the guys have said, its accurate enough for a TSS figure to keep your data up to date.

    It won’t cope well with a couple of sets of anaerobic intervals but for a long steady tempo ride or 2×20 it won’t be far off.

    To be honest though, if you’ve got access to a PM most of the time, previous experience will tell you to within a few points what the TSS will be. After using a PM for 8+ years I can put the head unit in my back pocket and tell you the NP/IF/TSS for any given ride to 1 or 2% accuracy.

    barrykellett
    Member

    LS – Member

    To be honest though, if you’ve got access to a PM most of the time, previous experience will tell you to within a few points what the TSS will be. After using a PM for 8+ years I can put the head unit in my back pocket and tell you the NP/IF/TSS for any given ride to 1 or 2% accuracy.

    True
    Except when it comes to the TSS out of a race for me. It always feels about 50% harder than the true figure 😯

    Where hrTSS is pretty much useless too

    monkeyfudger
    Member

    I’ve had a P2M for a while now, maybe even a year. It’s been absolutely flawless, even after being ridden through an insane reliability ride that consisted of a shit load of nigh hub deep water with the final “puddle” being deep enough to cover my foot at the top of the pedal stroke! The only thing that is irritating is the battery, no one seems to stock ’em.

    uponthedowns
    Member

    Dc Rainmaker reckons either P2M or Stages will do the job. However I’ve been using the P2M with Rotor 3D cranks for 2 and a half years now through all sorts of weather and in the Alps with no problems so if I were getting another power meter I’d probably go for another P2M.

    bob_summers
    Member

    What’s the crack with the battery on P2M? The DCRainmaker review mentions it has to be a certain brand, but surely not?

    monkeyfudger
    Member

    Ya, it’s got to be a Renata CR2450N. I’ve seen other CR2350’s (can’t remember if they had the “N” prefix) and they were different, the Renata one is a real chunky sucker with a broad shoulder.

    bob_summers
    Member

    OK ta for the heads up. Less than a fiver from Amazon, just as well coz I’ve never even heard of the brand.

    Premier Icon mrblobby
    Subscriber

    It’s almost worth trying to adapt to long cranks for that price 🙂

    TiRed, did you do anything to calibrate your PowerCal? Ordered one on a bit of a whim as I needed a new HRM anyway and it wasn’t much more cash. May come in handy when when riding without a proper power meter.

    barrykellett
    Member

    Planet x have the same cranks for £99 on sale – so really – you don’t have to adapt. Insane price. Breaking my heart and mind thinking about it!!!

    Premier Icon mrblobby
    Subscriber

    Didn’t realise it was a fairly easy job to swap cranks on an SRM… now that is worth thinking about 😕

    barrykellett
    Member

    Can you hurry up and buy it and get a mate to buy the other one too please

    Premier Icon flap_jack
    Subscriber

    I found pedaling efficiency to be interesting – I was appalling and by concentrating on this saw rapid improvements. This was on an old polar, which was a real rough approximator, but still useful. I increased average speed on my sunday ride by 10% in a few months by concentrating on style…

    bob_summers
    Member

    Cheaper still (than SRAM above) is barrykellet’s £99 crank + p2m type s meter w/o crank = £850.

    No good for my BSA BB, like.

    Premier Icon njee20
    Subscriber

    Cheaper still (than SRAM above) is barrykellet’s £99 crank + p2m type s meter w/o crank = £850.

    Or the normal P2M for even less. No good for me either, irritatingly.

    Premier Icon mrblobby
    Subscriber

    Rotor do a BB that fits BSA threads and takes a BB30 crank.

    bob_summers
    Member

    The winner for me is still the old P2M in rotor 3ds. The SRAM setup would be a fair bit heavier I think.

    DT78
    Member

    I’m in the states in sept…do you think there will be any warranty support issues if I buy over there and bring back to the uk?

    dirtyrider
    Member

    Rotor do a BB that fits BSA threads and takes a BB30 crank.

    this

    plus e13 do one as well, but its a bit shit but cheaper

    Premier Icon mrblobby
    Subscriber

    Yeah, same here. If only Stages were about 400 quid, I’d have brought two or three by now 😕

    dirtyrider
    Member

    stages not compatible with a Krampus as i found out the other day 🙁

    TiRed
    Member

    My powercal is compared with my Stages. Now i have two head units, i’ll run some direct comparisons for commuting, training and racing. I have a couple of datasets for srm and powercal, and i have deconstructed their algorithm for one dataset.

    DanW
    Member

    I’m in the states in sept…do you think there will be any warranty support issues if I buy over there and bring back to the uk?

    You would most likely have to send it back to the US if there were any issues but I think I wouldn’t worry about the smallish postage costs vs massive initial saving. Don’t think it should cause any problems besides this don’t think they should refuse to warranty it just because you are in the UK for example).

    i have deconstructed their algorithm for one dataset

    So how does the Powercal go about it’s business? Do tell 😀

    TiRed
    Member

    It uses a regression of power as a function of heart rate and its first derivative. I also looked at second derivative, but this didnt improve prediction. It could be incorporated into any HR monitoring head unit

    uponthedowns
    Member

    Dunno about having to use a particular brand of battery in the P2M. I use Duracell’s in mine and they work fine

    Premier Icon mrblobby
    Subscriber

    Thanks TiRed, I was more just wondering how you actually set the thing up. Is there some sort of field test to calibrate it so it gets an idea of how your HR and power correlates?

    DT78
    Member

    Probably a dumb question but has anyone compared the figures strava comes up with as estimated power vs a real power meter? Is it widely different? If it is a consistent variance, like always 10% more or less it is still useful for training and tracking improvements…

    Reckon I will pick up a stages when in the us. Random question, anyone know of a shop in San Francisco that would likely have stock of the rival crank?!

    DanW
    Member

    If it is a consistent variance, like always 10% more or less it is still useful for training and tracking improvements…

    I am no physiologist but I would have thought 10% variance is way above anything useful. No idea how Strava goes about its business but if it has similar outcomes to Powercal described above then it sounds like it would be pretty reasonable for long duration, constant efforts without a lot of short and high power sections. Well… ignoring cardiac drift and so on… which begs the question… why use it over HR on a practical level? I understand the difference in the calculation but does the Powercal tell you anything about your effort that you couldn’t have gained directly from HR? I can’t really get my head around this

    TiRed
    Member

    Powercal doesn’t use calibration for subject. They tried but found it added no additional accuracy. It sends to ANT+ signals; HR and power, and you can deconvolve power to reconstruct the algorithm (or a rough version of it). I don’t know which algorithm Strava uses for HR.

    I bought my Stages in the US just as they were launched. Stages have been absolutely faultless in supporting their product, despite two failures, and have sent me replacements immediately. Give a few bike shops a call and ask hem to order you one for collection.

    EDIT

    does the Powercal tell you anything about your effort that you couldn’t have gained directly from HR

    It tells me I’ve stopped at traffic lights 😉

    More seriously, it gives me a reasonable 30 sec average power that I have used when on other bikes to fill in data and monitor Normalized Power. It’s not going to help with 3sec sprinting efforts.

    DanW
    Member

    More seriously, it gives me a reasonable 30 sec average power that I have used when on other bikes to fill in data and monitor Normalized Power. It’s not going to help with 3sec sprinting efforts.

    I’m not sure on the exact response of HR to effort but HR seems to too slow to respond to even 30s or 1 minute efforts when you look at power and HR side by side. Going from recovery/ endurance pace in to a 10 minute interval at Threshold for example takes around a minute for HR to raise to a stable level which then rises of the duration of the interval (despite constant power). So, the fact you get a 30s moving average of HR is nice but you wouldn’t think should relate to power particularly well given that the time it could take for HR to respond to a change in power (the response time and window length together must miss a lot of information). Suggesting too that everyone produces the same power at the same HR is odd too (or at least that an individual will not change their HR/ Power relationship- energy efficiency?- with training). I just don’t get it 😕

    It looks like it gives some nice different numbers but actually HR isn’t such a bad thing for most people to use to gauge effort (is the Stages and Powercal measurements tie up as they seem to above).

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