Power meters – what are my options

I’m looking at power meters and I’m not sure the best route to go. I’ve just bought new cranks (SRAM Force) so don’t really want to get rid of them, I run Royce hubs so am definitely not swapping the wheels out and I’m quite attached to my 105 pedals and all the power pedals seem to push you down the Look Keo route.

Is there an option I can consider or am I going to have bite the bullet and swap out one or other of the above (ie the pedals as it’s not going to be the cranks or wheels).

https://www.sigmasports.com/item/Stages-Cycling/Carbon-Power-Meter-Crank-Arm-for-SRAM-GXP-Road-2nd-Gen/DRWR?utm_source=google&utm_medium=base&utm_campaign=base&co=GBR&cu=GBP&glCountry=GB&gclid=CjwKCAiA8vPUBRAyEiwA8F1oDEFVBKWpgfUKQkKqhCM2Ep9ZuUkqxmnEL-54YE9O99XpsVyrozqfVhoCVXwQAvD_BwE&gclsrc=aw.ds

Nice – thank you. That looks promising.

I’ve got stages, but am now on my 4th unit as the last 3 have failed, so I wouldn’t recommend them.

Assuming your chainset is the new force 11, power2max would be worth a look:

https://www.power2max.de/europe/en/Produkt/favorites-en/power2max-ngeco-sram/

I’ve got 2 Power2Max’s and they’ve both been great, in all conditions, over 2-3 years. One is on the winter/bad weather bike too.

Only heard good stuff about Power2Max but that’s a full crank.

Stages, well, unfortunately like rossp I had 3. First failed after 18 months but they changed under warranty, second arrived with problems, and third (warranty replaced again) I never bothered opening and sold BNIB on eBay. A month later the guy came back asking where I had bought it since it had failed…

Please note, Stages/Saddleback gave stunning customer service with fast responses and replacements. It’s just such a shame the product is pants.

A very good alternative for a left-hand only PM is to look at 4iiii. Mine has been faultless. I have no information on Pioneer who seem to be on the rise as well in this market.

Otherwise you can look at pedal based ones (P1, Vector, etc) where you can get dual-sided information (L/R power balance on your legs) if you need that. Please note Vector pedals need torqued correctly to work properly. Or of course rear wheel stuff.

IMHO best, cheapest option right now is the 4iiii. Easy to swap between bikes (if you use the same crank length of course) and it just works.

But as always with this area, start on DCR and see what he says. It’s not necessarily perfect but he is good and independent. 2017 powermeter comparison link here.

I had to return 3 or 4 Stages under warranty but now I have a G2 one it seems ok.  Nowhere near the claimed 200hours but maybe a month or so of riding.  Seems quite dependent on battery quality

I’d bite the bullet and go for Look cleats, or wait for Garmin to release their next generation Shimano pedals. Personally I like the Favero Assiomas because the feedback on reliability for the original Be Pros and Assiomas has been so good. Swapping with a large pedal allan key rather than spanner is an advantage -as is USB rechargeability, assuming you plan on swapping. I’ve run Stages and had one of the very first first gen models in the UK. It didn’t survive the first cold wet ride, had another and the same happened. Customer service was good, and they changed the bonding of the pod. I just think that pedal systems are now the way forward.

Only downside of the Favero is that the single-sided Uno currently only sends Power/2 via Bluetooth to Zwift. If that matters to you.

Conversley, I have a Saint G1, XT G1 and 2 G2 ultegra Stages and only the Saint one has been back. Ridden in all weathers for the last 4 years but bikes kept indoors.

You should be able to get a Power2max to fit your cranks.

Only issue with the crank power meters is the pain to swap between bikes.

Garmin Vector 2s can be converted to SPD with a kit costing around £90. Vector 3s seem a much better design though so are probably worth the hassle of changing to Look Keo cleats.

I have a P2max type S which is really reliable so I’d give them the thumbs up. Have recently ordered a set of Vector 3s so I’m in the process of changing over from SPD to Keos. Trying to do it cost neutral by selling my Shimano pedals then buying 2nd hand Look pedals.

If you want a power meter that is not crank based and can be swapped between bikes have a look at the Powerpod.  DC Rainmaker has a pretty in depth review on his website.

I’ve just got one but don’t have it setup yet.

Ah but the PowerPod does not measure your power output. For me that’s a dealbreaker

It does, but it just doesn’t use a strain gauge.

Not trying to be argumentative but it basically measures speed, elevation gain and air pressure/wind resistance. You input a value for rolling resistance and your CDA It then calculates an inferred power figure.

It does not measure your power output.

No, it infers it.  But it’s pretty good according to those who’ve tested it against other PMs. It has the advantage of being portable and cheap, and the disadvantage of somewhat lower accuracy.

My Stages power meters have been fine now I’m on a G2.

Favero been faultless through grimey winter, great kit, great pedals too.

That Powerpod looks seriously tempting for the price; I’d not heard of it before this thread.  Just read the reviews and I’m impressed.

Well I also run two powerpod and a Powercal. Powerpod does give reproducible power measurements provided it is set up carefully. You need the Garmin magnetless speed sensor and some patience. Swapping between bikes, whilst widely advertised as easily, is a pain, I think swapping a single pedal will be the fastest.

Btw none of the powermeters measure “power” if you want to be pedantic. Force meters measure crank deflection or pedal torque, then need cadence to estimate a velocity and power is force x velocity. One reason why oval chainrings are troublesome,

Personally, I’m working on an algorithm that i’ll calibrate against powerpod, assioma and powercal, and run on a Garmin without a meter. I already have it running against Quark.

Got a rotor rex 1.1 in power on my mtb and it’s been flawless.

To me power in cycling is force/torque applied to the pedals multiplied by the speed you turn the cranks. Force applied is measured by strain gauges in the pedals/cranks/hubs. What more would you want a power meter to do?

The PowerPod looks really interesting to use with a power meter to figure out what’s slowing you down e.g drag.

Force is not power. And yes the powerpod will give you a measure of CdA when paired with a power meter. If you were to buy the old Newton bike computer and pair with a force power meter you can see CdA in real time whilst cycling. The powerpod stores the data for download later, and you can’t send it to the Garmin, sadly. Maybe one day. It’s where the technology is going.

Obviously being a physics geek, I rather like the Powerpod, it’s a reverse estimation of force (measure opposing forces), but that is still a measurement of force. Combine that with speed and you get power. The Powercal uses a regression of rate of change of heart rate and power to estimate power with no measurement of force. On 30 second smoothing, it’s pretty good too. I’ve done Chung CdA analyses at hillingdon using it with believable results. Which was a surprise to me!

IMO the Powerpod is a settlers delight,  and constantly needed the software playing about with especially if you move it.

I moved to a 4iiii over a year ago which has been constantly reliable an needs nothing doing to it except a once a year battery change, of 5 minutes and a 1 minute calibration to move across bikes.

And for some more physics geekiness, if you want to know what your power meter is really measuring…

https://www.omega.co.uk/literature/transactions/volume3/strain2.html#

Nice explanation of how strain gauges work. Basically, I think people over-think this with a passion.

If you find a nice hill to ride up, and know the incline you can estimate power output too. No force measurement required:

Power Watts/kg = 3 * slope * velocity (km/hr)

So climbing Alpe d’huez (8%) at, say 10 km/hr will need 0.08*10*3 = 2.4 watts/kg

Fancy yourself as Marco Pantani (without the coke), it’s 14.5 km in 37.5 minutes or 23.2 km/hr

Power is a mere 0.08*23.2*3 = 5.6 watts/kg

PS The actual conversion factor is not 3, but 9.80665(m/sec/sec)*1000(m/km)/3600(sec/hr = 2.74. For mph the factor is 4.41.

This method works because it assumes steady state (no changes in kinetic energy), ignores air resistance (you are climbing relatively slowly) and rolling resistance (typically about 10-15 watts or perhaps 0.1-0.2 watts/kg). The use of 3 and 5 factor in these missing losses. Pantani was going faster so his actual watts/kg was even higher!

Have been using Powerpod for a while now. It does take a while to set up but once that has been done it gives consistent power readings.

It does give some odd readings in some circumstances but not enough to be an issue.

I have not had any issues switching it between bikes. The key is to make sure you have it such that when you rotate it into position you use the stop on the supplied mount. It can be sensitive if you don’t get the orientation right. It will self correct in 8 minutes of riding though. I rotated the go pro mount back so that when it is set level it stops against the handlebar. Works for me.

It has occasionally not connected to my Garmin if you stop mid ride for more than 20 minutes. A soft reset sorts that. Also it can be affected by heavy rain blocking the wind port. I have had this only twice in a lot of wet riding.. It works fine again once dried out.

It automatically switches between immediate and power smoothing mode which is good for intervals etc. In my experience there is a slight delay in the power reacting but only about 3 seconds or so.

Works well in Trainer mode for the turbo too.

For the price and ability to move between bikes it is good value. I haven’t used a crank based system to be able give a companion. Tired would be the man for that opinion. Would be interested on your developments in HR based power Tired.

I’ve got a Powertap hub built up into a rear wheel, lasted six years so far with just the odd battery change maybe once a year. Also got a pair of the Powertap P1 pedals, batteries don’t last that long in them perhaps 60  hours, really easy to swop between bikes as no funny torque settings for them etc… left/right power and thru the entire stroke measurement a bit meh to be honest, Look Keo cleats yup I prefer the Shimano ones too.

Main thing is you have a reliable power measurement, remembering with Powertap to calibrate before each ride.

Big BIG tip…… a lot of Cycle2work schemes count pedals as accessories…. just saying like 😉

Tired interesting calculation for climbing, thanks for that. I reckon wind has a huge impact on a climb even though your travelling slowly. On our local hill climb winning times vary from 3m35 to 4m15 depending on wind direction. That’s over 15%. On Alpe D’Huez that could be 9 minutes or more if your a slower climber. You may think you’ve climbed it at 4w/kg but you had a tailwind so were only putting out 3.5.

I had my first ride out with a Powercal today after a couple of years with Powerpods.  It’s actually quite impressive really, even if it’s not totally accurate (I’ve nothing to compare it to at the minute) the fact that they can get it in the right ballpark just on hr alone is pretty cool.

Having said that, a combination of xert’s “what’s my ftp” ConnectIQ data field and a Powercal returned a value of 235w after today’s ride.  My ftp when I did a proper ftp test on a warmed up smart trainer a couple of weeks ago was 233w so there’s some pretty fancy maths going on somewhere!

I’ve no real need for a power meter so I don’t mind about accuracy so much as taking an interest in the tech aspects hence Powerpods and Powercal rather than something more conventional.

I compared my Powercal with my KICKR on a 90 minute three lap Zwift route today. On average, the Powercal was down about 5-10% per lap, but it was perfectly reasonable (Zwift was using the Kickr, Garmin recorded Powercal) – and about as inaccurate as my speed sensor and dumb trainer with zPower.

BTW, Zwift are recommending the Bluetooth Powercal for a cheap introduction to get you started, as Zwift needs a power input. They even sell it in their shop.

The Powercal has been my most robust power meter by far! We shall see if the Assioma Uno lives up to expectations. I have several years of data and have compared it with direct force and powerpod.

I would have thought Zwift wouldn’t be an ideal scenario for the Powercal to be honest – the impression I get from the dcrainmaker and titaniumgeek reviews is that the data’s very jumpy unless heavily smoothed which would then make it difficult to accelerate to cover an attack or whatever.

I thought the same. You won’t be using it for racing, or possibly group rides, but for just riding around, it’s fine. Titaniumgeek is also using his to row a Concept 2 on Zwift. I can’t really test mine, as it is ANT only, and I use iOS Zwift on an iPad.

Average watts is close enough to make it useful.

I had a Stages G2 on my last road bike, it was faultless other than needing a new battery now and then. New bike has different cranks on it so I’ve sold the stages and gotten the new Garmin Vector 3 pedals as I don’t want to have to buy a new power meter every time I get a new bike. I read a lot of reviews on them prior to purchase and so far they seem pretty decent and easy to swap between bikes.

+1 for garmin vector pedals. No hassle to change bikes. Accurate enough for us mere mortals 😉