Those are the two on the shortlist, as I can't spend SRM money, and don't think a powertap would work for me (switching wheels too often). On top of that, I've broken my crank so was thinking of killing two birds with one (expensive) stone.
Has to work with Campagnolo 11spd, BSA BB, Garmin Edge 500. I was leaning towards a P2M in Rotor 3d flavour, but I know a few here rate the Stages (would mean buying a FSA Energy or SLK crank). I've read the in depth reviews on DCRainmaker but none the wiser really.
The Stages is lighter and cheaper, but that's it. If you're not too worried by either of those then I'd get the P2M all day long, much more accurate, none of the reliability problems, more data - left:right splits and such.
Stages doesn't work with carbon cranks, so that only leaves Campy Athena as an option for 11sp.
Stages would be my choice though, especially as Sky are now them and this will hopefully lead to better development etc
Been thinking about this a while too and I'm tending towards a P2M with the Rotor crankset. Accuracy and reliability being the main points.
Doing the maths, I don't think there's a lot in the price, being as I need a crank anyway. FSA Energy + Stages + BB is about 850EUR, same as a P2M Gossamer (which is a boat anchor) - another 100€ gets the Rotor version. Could be worth the extra money?
SwedishChef, no Campag options at all for Stages, but the FSA cranks would work fine.
Power2max without a doubt.
Why measure power on only one side make assumptions when you can have the real McCoy for almost the same money.
Speaking as a stages owner
P2M every day of the week! I've got the Rotor 3Ds and it all works perfectly (long-time but now hacked off Powertap user here), every time.
Stages is far too much like guesswork for me.
If I had the money to drop it would be a P2M for sure.
Are you using the older version P2M LS? If I understand correctly, the old version (ie the triangular pod) now has the new firmware, so paying extra for the Type S only really saves weight, you don't gain any functionality aside from being able to fit oval rings.
Just went and looked at the UK RRPs for Stages, OOF! Definitely P2M!
Why measure power on only one side make assumptions when you can have the real McCoy for almost the same money.
P2M is only one sided... as is SRM and Quarq.
I know the measure things differently, but one sided none the less.
P2M is only one sided... as is SRM and Quarq.
Not really - the strain gauges know how hard you're pushing with the left leg because of the deflection at the spider. You can ride a P2M/SRM/Quarq one legged (with the left leg) and still get a reading. A Stages has absolutely no idea what your right leg is doing, just assumes it's the same.
Yes, but it sits on one side - not both, like Garmin Vector for example.
I am just being a pedant, obviously 😉
Friend has stages, had to go with a rival crank for his red chainset. He has had it a couple of months now and rates it.
Possible weaknesses of P2M are that left/ right balance is still an estimate and based upon a series of assumptions (although less than that of the Stages assumptions). Also, possible servicing and warranty help- not sure how that looks in the UK at the moment.
Stages seems nice, light and convenient if you already have cranks but much less of a bargain if you need to buy the cranks too. The main selling point of Stages is price IMO and when it starts to get up to P2M/ Rotor money (and you have to add a heavier alu crank than you'd probably rather run then the weight advantage disappears too) then it looks a whole lot less attractive.
Have you considered the [url= http://www.velotechservices.co.uk/shop/vclose2.asp?prd=134495&cat=7382001346 ]Rotor Power Crank[/url]? It is the only set up to actually measure left/ right independently which gives you metrics like Torque Efficiency and Pedal Smoothness. Probably doesn't mean much in the real world and for day to day use but perhaps a nice addition to have "just because" considering the unit is the same price as a P2M set up.
EDIT: Beaten to it on the left/ right assumptions of spider based power measurement like P2M/ SRM 😀
Rotor Power Crank
Quite a bit more expensive than a P2M though.
As above - Stages is one sided and simply doubles the numbers, whereas P2M is both-sided (it makes a guess at L/R balance). Both are compromises, but the P2M seems less of one.
In my case, I don't envisage needing to know my pedaling dynamics or smoothness. I was happy just having overall power last winter on the turbo (albeit virtual) and would like similar on the road too.
The Sky tie-in surprises me - with their marginal gains etc, it's strange that Froome would be training with a compromised design. Either his L/R balance is exactly 50/50 😉 or Stages have got something interesting in development.
Quite a bit more expensive than a P2M though.
Rotor can be had for ~£1200... how much are the cheapest P2M? ~£1000? It isn't a SRM-type jump in price but true it looks to be a few hundred more
I dare anybody to tell me the power output difference between left & right leg and if it actually makes any difference. Also fluctuations in power are so random as the terrain you ride changes so often that's why Coggan & Allen came up with normalized power. It's being consistent that's important and I have used stages & SRM with no difference in data.
Rotor's too much for me, looking to spend less than a grand (eur) inc rings and bb.
Either his L/R balance is exactly 50/50 or [s]Stages have got something interesting in development[/s] Sky are running power meters on both cranks.
Maybe? Anyone checked?
The main selling point of Stages is price IMO and when it starts to get up to P2M/ Rotor money (and you have to add a heavier alu crank than you'd probably rather run then the weight advantage disappears too) then it looks a whole lot less attractive.
I was shocked to see that a Dura Ace 7900 or 9000 Stages is £800, considering you can't get a chainset with a LH crank so you then have a spare that strikes me as excessive. A Rotor 3D P2M is only £750 for both cranks and the spider.
Sounds like you needed a spare LH crank arm with the teething problems they had!
I'm starting to think the Stages would be perfect for me but is about 200€ overpriced.
Are you using the older version P2M LS?
Type S - it looks nicer 😀
Toying with the idea of putting the original type on the winter bike to replace my last working PT before it dies.
The Sky tie-in surprises me - with their marginal gains etc, it's strange that Froome would be training with a compromised design. Either his L/R balance is exactly 50/50 or Stages have got something interesting in development.
Is a little surprising, I'm guessing they are getting paid to use/market them. Though don't BC use wattbikes, so maybe they do most of their testing and analysis on those.
Must admit I'm tempted by a Stages as a cheapish option. I have the powertap on the turbo for power based intervals where I'd want something as accurate as possible. The Stages for training rides and club runs would be handy for some analysis, working out TSS etc. Or I may move the power tap onto the training bike and get a Kickr for indoors. Argh too many (expensive) options!
No Drive side Stages on Froome's bike at the Dauphine 😀
[img] 
[/img]
The Sky tie-in surprises me - with their marginal gains etc, it's strange that Froome would be training with a compromised design. Either his L/R balance is exactly 50/50 or Stages have got something interesting in development.
It was costing Sky a fortune to buy the required number of SRM's and not all team members were able to be supplied with their own units plus it is difficult to swap between the number of bikes the pros use. I guess Stages makes the mechanics life easier and remember too that Stages are reported to have paid Sky a 6 or 7 figure sum of money for the privilege of appearing on the "marginal gains" team. No-one really knows if L/R balance is important and I know from my own riding on an Ergo that my L/R balance was only 49/ 51 when recovering from knee surgery. I would have thought the pros are far smoother and balanced than that! On top of aaaaallll of that some SKY guys have been pictured with blacked out SRM spiders, just as some of the Garmin guys run dummy Vector pods and blacked out SRM's.... nothing is clear cut 😀
No Drive side Stages on Froome's bike at the Dauphine
Can you tell from that photo? Can't really see the inside of the NDS crank.
I was shocked to see that a Dura Ace 7900 or 9000 Stages is £800, considering you can't get a chainset with a LH crank so you then have a spare that strikes me as excessive. A Rotor 3D P2M is only £750 for both cranks and the spider.
What bugs me is there's (AFAIK) not much difference between any of the shimano LH crank arms, all the tech seems to go into the right and the rings, yet the price difference between the 105 crank and a DA crank is almost as much (£200 Vs £270) as a DA chainset!
Do stages have to pay full RRP for chainsets then bin the right hand arm? The price wouldn't be hard to swallow if it included the RH crank too! Or they had a UK distributor you could send LH cranks off a new bike to and have them added.
I'm starting to think the Stages would be perfect for me but is about 200€ overpriced.
I'm sure the initial pricing was about $700 for a Dura Ace one, which seems about right. Seems now it's decidedly mid-ranged, more expensive than Powertap, P2M, pushing Quarq too by the time you factor in the chainset.
Toying with the idea of putting the original type on the winter bike to replace my last working PT before it dies.
How do they die out of interest? Mine is about 5 years old now, eats bearings, but other than that and batteries it's never missed a beat, gets completely neglected too!
What bugs me is there's (AFAIK) not much difference between any of the shimano LH crank arms, all the tech seems to go into the right and the rings, yet the price difference between the 105 crank and a DA crank is almost as much (£200 Vs £270) as a DA chainset!Do stages have to pay full RRP for chainsets then bin the right hand arm? The price wouldn't be hard to swallow if it included the RH crank too! Or they had a UK distributor you could send LH cranks off a new bike to and have them added.
Agreed, in the US you could buy a whole chainset, which lessens the blow a little if you're building a bike or sommat.
[b]mtbmatt - Member [/b]
P2M is only one sided... as is SRM and Quarq.
I know the measure things differently, but one sided none the less.
it might [b]be[/b] on one side - but it is not measuring one side.
I'm sure you can grasp the difference in measuring torque on a crank arm as opposed to the crank spider and are just trying to stir the pot with word play
How do they die out of interest? Mine is about 5 years old now, eats bearings, but other than that and batteries it's never missed a beat, gets completely neglected too!
Was going to ask the same thing. Mine gets neglected and has been faultless. Though it does pretty much only get used indoors!
Do stages have to pay full RRP for chainsets then bin the right hand arm?
Haha, I did [url= http://singletrackmag.com/forum/topic/stages-power-cranks ]wonder exactly this a few weeks ago[/url]!
I am selling an as new Quarq in classifieds!
Though it does pretty much only get used indoors!
Whilst mine got ridden through at least 5 hub-deep floods over winter with nary a sniff of trouble!
Sky don't use Watt bike they do their testing on the bikes in the lab on a giant treadmill with rider strapped into a hoist. As I mentioned left or right isn't relevant it's consistency in readings from Normalized/AVG power avg 20 min etc & % of FTP and Sky will also be using quadrant analysis.
My PT died this year, directly after the winter indoor season.
Still gives out readings that are correct, but will suddenly spike or drop off completely. Needs to be looked at by a PT specialist as the LBS can't do anything.
Contacts anyone?
A Rotor 3D P2M is only £750 for both cranks and the spider.
Wow! That really is fantastic value (comparatively). P2M all the way then 😀
Do any of the P2M MTB versions sell for that sort of money too?
I was shocked to see that a Dura Ace 7900 or 9000 Stages is £800
Completely agree. Selling them for £5-600 would be far more attractive. I think it is partially due to the distributor in the UK (a bit like the US and UK price for Santa Cruz stuff) where the Stages crank I was looking to buy is $700 in the US but Saddleback quoted me £850! Also, potentially high costs to Stages to acquire individual crank arms from manufacturers who may have existing agreements in places with other power meter manufacturers. Some companies also seem to penalize the UK compared to Europe for some reason- the LBS was complaining that SRAM in particular set the price to the distributor much higher in the UK than the EU which means LBS's and even online shops that can only source stuff from the UK distributor can't get anywhere near competing with the EU, let alone the US.
it might be on one side - but it is not measuring one side.I'm sure you can grasp the difference in measuring torque on a crank arm as opposed to the crank spider and are just trying to stir the pot with word play
No, spider based measurements measure net torque produced. You can't measure if the left and right legs are working against each other at any stage for example. A true left and right measuring system like Rotor or Garmin measure the [i]actual[/i] power produced at either side to be able to then display net power produced as well as what they call "torque effectiveness". It isn't just word play but whether it matters in the real world is another thing
DC probably explains better than we can 😀
[b]Estimated Left/Right Power[/b]: This became all the rage over the last 18 months or so, starting with the SRAM/Quarq RED unit offering left/right power. That platform works by essentially splitting your crank in half and assuming that any power recorded while pulling up is actually coming from the left side, whereas pushing down is from the right side. Thus, an estimation. It’s good, but not perfect. Note that even with true left/right power (below), there’s actually very little in the scientific community around what to do with the data. While you may think that perfect balance would be ideal – that hasn’t been established. And some that have looked into it have found that trying to achieve balance actually lowers your overall output. The only thing folks agree on is that measuring left/right power can be useful for those recovering from single-leg injury.[b]Actual or True Left/Right Power[/b]: This is limited to units that can measure your power in more than one location. Thus why we see it on pedals, as well as the more expensive crank-arm based power meters. You can’t measure it directly at the spider, instead you have to measure it upstream of that.
[b]Pedal Smoothness & Torque Efficiency[/b]: These two metrics are just making it into the high-end power meters which contain true left/right power measurement. Today that’s only the Rotor and Pioneer units, but Garmin has stated they’ll be adding it down the line via firmware update.
Do any of the P2M MTB versions sell for that sort of money too?
Sadly not [url= http://www.power2max.de/europe/en/Produkt/power-meters-en/rotor-3d-mtb/ ]€1230 for a Rotor 3D[/url], presumably as they don't do the volume.
A bit of Googling yielded a Dura Ace Stages for [url= http://www.probikesupply.com/stages-shimano-dura-ace-9000-power-meter/# ]£528[/url], plus shipping, or £792 including the chainset. Bit more like it! On closer inspection they (along with several others) won't ship, which is a pain. Stages trying to close that door I wonder?
This is a long read but if you stick with it is really helpful http://www.dcrainmaker.com/2013/06/stages-review-update.html
The Sky Stages have blue covers so you can just about make it out on his NDS crank, but nothing on the DS (referring to the pic on p1)
The Rotor thing is odd too. They seem to be selling OE cranks without spiders or rings to P2M, yet are also trying to flog their own PM system for a few hundred more.
680 quid [url= http://www.powermeter24.com/en/products/stages-power/stages-powermeter-shimano-dura-ace-7900-7950 ]here[/url] which is a bit better than 800 quid. TBH I'd probably just get the 105 version, I think they fit fine on Ultegra and DA chain sets, it's only 530 quid, and I'd probably do a TiRed and wrap it in an inner tube anyway.
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.
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
[b]I've read the in depth reviews on DCRainmaker but none the wiser really.[/b]
^ 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 😀
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.
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?
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...
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 2x20 it won't be far off.
Durian rider does a very good comparison video on these and the guy rides ALOT
Stages Cycling Power Meter Review #2:
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 2x20 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.
[b]LS - Member
[/b]
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
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.
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.
What's the crack with the battery on P2M? The DCRainmaker review mentions it has to be a certain brand, but surely not?
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.
OK ta for the heads up. Less than a fiver from Amazon, just as well coz I've never even heard of the brand.
shame these wont fit
http://www.chainreactioncycles.com/sram-srm-power-meter-double-bb30-chainset/rp-prod51611
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.
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!!!
Didn't realise it was a fairly easy job to swap cranks on an SRM... now that is worth thinking about 😕
Can you hurry up and buy it and get a mate to buy the other one too please
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...
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.
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.
Rotor do a BB that fits BSA threads and takes a BB30 crank.
The winner for me is still the old P2M in rotor 3ds. The SRAM setup would be a fair bit heavier I think.
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?
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
Yeah, same here. If only Stages were about 400 quid, I'd have brought two or three by now 😕
stages not compatible with a Krampus as i found out the other day 🙁
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.
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 😀
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
Dunno about having to use a particular brand of battery in the P2M. I use Duracell's in mine and they work fine
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?
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?!
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
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.
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).
