Where To Fit A Power Meter On Your Bike | GCN Tech Does Science

(dramatic thuds) (upbeat music) – Training with power has become one of the most talked about ways of both improving performance and
fitness in recent years. Gone are the days of being out, slogging yourself for hours on end, and well, just hoping for
the best in terms of fitness. However, what’s really
important is actually the consistency of data in which you’re getting back from a power meter. As much as we all like to think we’ve got a really high number,
if it’s wildly inaccurate, well, it’s not really
gonna help you is it? So, thanks to our friends at PowerTap, we’ve got a few different
ways in which we can measure power whilst you are riding along. So, come on, let’s go
and take a look at it. Now, where exactly are we gonna measure all this power from, then? Well, we’ve got five different devices that we are gonna connect to and see just how accurate that data can be. (upbeat music) First up is the PowerTap Rear Hub. Now, the PowerTap hub system has been around for about 20 years now. Obviously during that time,
it’s undergone some refinements and developments, and
it’s gone from what was initially a wired unit,
to what we now have, a wire-free unit, which is good
news for everyone out there who doesn’t like extra
wires on their bikes. So, this is the G3 Hub,
and as you can see, it’s an oversized hub-shell unit, which all of the strain
gauges and electronics are actually housed
within, and then the torque you’re putting through the
rear wheel is transferred, that data into power,
sent on to the head unit. Now it is a very easy installation process if you buy a pre-built wheel. It’s simply a case of
putting it in the bike, pairing it up to your head
unit, and away you go. There’s also no need
to send the wheel back to a service center in the
case of a battery change. It is easily done by yourself at home, so simply unscrewing the endcap, and then replacing that
battery, nice and easy. Now I have already touched on it, but it is a really great
transportable piece of power measurement
equipment if you’ve got a few different bikes, so you
can simply remove the wheel and then put it into another bike and have power measured from that too. Now many experts like that actually claim that the hub-based system
is one of the most accurate ways to measure power out there, because, essentially,
you’ve got less variables that are going on, so there’s less things such as a chainring moving,
and that kind of thing. Now PowerTap, themselves,
have actually told me that basically the hub
system can sometimes underread that total max power,
the reason for that being, is obviously with the
drivetrain components, you do have a little bit of loss off that raw power
being sent through that. However, it is accurate to
plus or minus 1.5% accuracy, so you’re pretty much on
the money there, anyway. (upbeat music) Now, secondly, and this is
a relatively newcomer really to the power meter game, is pedals. So the PowerTap P1 Pedals, as you can see, there is the battery which is
housed inside of the unit here as well as the strain gauges, so basically it’s all tucked away nicely
underneath the pedal. Initially, they do look like
they have a little bit of bulk, but, hey, when you’re riding along, you can’t actually see
that anyway, can you? So it doesn’t really matter. And what do I really
like about these pedals? Well firstly, they’re highly
portable, aren’t they? So if you’ve got more than one bike, you can easily switch them
around from bike to bike, certainly easier than that
of a chainset, for instance. And say, if you had a hub
built onto a training wheel, you wouldn’t necessarily want to use that in a race situation, would you? And then we’ve got AAA batteries, too. So, if you were in the
unfortunate situation, and you forgot to actually
check how much power was inside of your
battery, and you ran out, you could easily find a AAA battery from virtually any shop on any
street in the world, I guess. Now, data, again is transmitted
for ANT+ or Bluetooth. And then in this case, we’ve
actually got dual-sided, so it’s a left and
right power measurement, so one pedal talks to the other, and then that pedal send the
information to the head unit. Now, there is also the option to run it as a single-sided unit, so you buy a pair of almost identical pedals,
well they are other than the right-hand side pedal doesn’t have any of the electronics inside of it. Instead, it’s the left pedal
which transmits the data to the head unit, and then
to find out your total power, essentially it doubles that
because most people out there actually have an even split
50/50 or there, or thereabouts. Now, finally, let’s talk about the actual cleat system that fits in here. Our first look, they do look extremely similar to that of a Look KEO pedal. However, they are slightly more oversized, so if you were to use a Look KEO in there, it’s not going to give you
that accurate power reading as well as potentially
being dangerous as you could unclip, so it’s worth
sticking actually with those PowerTap-specific cleats, which do come with six degrees float or fixed. And just like the hub system, it’s accurate to plus or minus 1.5%. (upbeat music) Now next up is the PowerTap
C1 Chainring systems. Now there’s no actual competition on the market for them
as far as I’m aware. So how do they work? So out of the box, they come as a pair of FSA chainrings which are
mounted onto what’s essentially a secondary spider, which
houses some of the magic of a power meter inside of it. And then, it’s also got the sender unit, so that’s the transmit via
ANT+ or Bluetooth again, as well as the battery which is fitted onto the chainring, too. That then fits onto compatible chainsets, so in this case, it’s 110 BCD,
and that’s a five-arm crank. And then, the actual
power itself is measured from the outside of the inner-chainring, which is really super
interesting, for me anyway. So interestingly, despite
the data collector actually being on the
right-hand side of the bike, it does actually measure
left/right balance. How’s that done though? Well, it’s all due to
the actual positioning of the chainring, so if you were to put it in a different position on the spider, it’s not gonna give you accurate readings. Now, it is actually done on
an assumption, basically, of your pedal stroke, so
hence the reason for it having to be in the right
place on the spider. (upbeat music) Heart rate. That’s right, I said heart rate. Nothing to do with power, although it is, because this is actually an
entry into the power meter game, because using a clever algorithm, you connect this heart-rate
strap to your head unit or your smartphone, for instance, and it gives you an estimation, basically, of your power output. Now, naturally, this is
no where near the cost of anything else on the
bike that we’re measuring power from, but it is a great
entry-level starting point for you to be able to train with power. And the great news out there for people who aren’t particularly technically-minded when it comes to changing
bits around on a bike is, well, it doesn’t even have
to go on a bike, does it? It just goes on yourself,
so you can use it across all of your different bikes. (upbeat music) Finally, we’ve got a
crank-based power meter here. This one from Stages, and as you can see, the actual electronic gubbins
of it are actually here on the inside of the left-hand crank. So, we’ve got the string gauges, and also a user-changeable
battery there, too. It doesn’t add much weight at all to the actual original
crank, and they do actually come in quite a few
different varieties, too, so matching up with most
chainsets out there on the market. And just like all the other power meters, or most of them out
there, you’ve got yourself a user-changeable battery, as well as connecting via ANT+ or Bluetooth. So we’ve gone through the
five different power meters, but how, actually, are we gonna measure and record the data being captured? Well, this is where this comes in handy, mission control, or something like that. Anyway, I’ve got five Wahoo
ELEMNT BOLT GPS devices. Each one is paired up to a power meter. I’m now gonna go out
for a pedal on the bike, and when I get back, I’m
gonna be able to analyze and see just how consistent
each power meter really is. (active music) So let’s look, then, at the
all-important consistency of the data that was being recorded. Now this is a little
bit of GCN Does Science, and I’m using DC Rainmaker’s
analyzer software here, so you can see there is
different lines on the graph, and that does represent each
power meter that we’ve used. On the far left-hand side of the screen, we’ve got the power measured in watts, and that’s versus time
along here at the bottom. Now if I was to hover my cursor, basically it lets me know what power meter is measuring what power up
here in the right-hand side. So we can actually see up-to-the-second information, which is pretty cool. Now you can see that
there is one power meter which is not tracking quite as high as the rest, but more on that later on. But the good news is, that by and large, everything is tracking
in the same trajectory, as you can see, so the lines do actually follow the
same, which is good news. Now first of all, let’s actually look at the uppermost three lines on our graph. So, as you can see, they
are tracking each other very closely, and on occasion, in fact, the pink and green ones are, in fact, shadowing one another,
giving very similar readings. So what are they? Well, the green one,
that’s the PowerTap G3, so that’s the hub-based unit, and then the pink one is the PowerTap C1, and that is very, very interesting indeed. They do track, like I say, and shadow one another at those peaks and troughs. Now as for the orange line, well that’s the PowerTap P1 Pedals. And you can see, again, it
does follow exactly the same lines as the other two power
meters I’ve just mentioned. There’s a slight dip
here, just after 11:39, and I know exactly what that was. That’s where I encountered some traffic, and I actually had to
unclip one of my pedals, because I had to stop
at some traffic lights momentarily before getting going again, so nothing to worry about there. Now those previous three power meters I’ve just spoke about all actually measure a left and right power
measurement, giving the total. Whereas the Stages,
which is the blue line, just measures the left,
and then doubles it up and gives you your total power reading. Now I know, from a serious
crash I had a few years ago, that my left leg is considerably
weaker than my right, so that could be why it’s not
giving such high readings. But essentially, it is still tracking on the same lines, so
we’re all good there. Now for the black line. So this represents the PowerCal, which is the heart-rate based power meter. Now instantly you can
see it does lag slightly behind the peaks and troughs
of the other power meters, the reason for that being,
when you are putting in any momentarily anaerobic effort, obviously your heart rate
doesn’t instantaneously react to that, so that does explain it. Plus, it does also follow,
generally, the same lines, so that is good news after all. Now, at this point, I must actually say that PowerTap, themselves,
say the PowerCal is not the be-all and end-all solution
to training with power, it’s more of an introduction to it. Also, my maximum heart
rate is actually quite low for my age, believe it
or not, so it’s 174. It always has been, ever
since I started training with heart rate back in
1995, believe it or not. So that could be, possibly,
why my power reading isn’t as high as the
rest, so that’s obviously using the formula of 220 minus your age being your maximum heart rate. But, the good news is,
like I said earlier, it does track, generally,
in the same trajectory as the other power meters out there. So what’s important
here is that, generally, all of the power meters
do track with one another, so there’s no crazy dips
or spikes in the graph, which is basically gonna give you misleading results in the long-term. Now, as for is there a
best place to actually put a power meter on the bike? Well, there’s a few variables here. So, your budget as well
as compatibility issues. So if you’ve got just one bike, maybe the chainring solution is for you, because that’s very much a
fix-and-forget type situation, cause you don’t want to be
swapping them from bike to bike. A couple of bikes, maybe
you’re looking at the pedals to move around, and the
same goes for a wheel too. Just think about the future if you’re gonna buy any more bits of equipment. So there we are. I’m sure you’ll agree some pretty interesting results, there. But what I really want to know
is, do you train with power, and if so, what method do you use? Let me know down there
in the comments below. Remember, as well, to
like and share this video with a friend, especially if you’ve got a friend who trains in the Dark Ages, and just smashes himself for hours on end. Anyway, do remember as
well, check out the GCN Shop at shop.globalcyclingnetwork.com. And also, check out another video on training with power, click just down here.

100 thoughts on “Where To Fit A Power Meter On Your Bike | GCN Tech Does Science

  1. Pedals… so I can have any wheelset I want. I have separate race wheels and that is why I like pedals. Or for travelling. Tiny, easy, fits all bikes. Like when I visited Alpe D'Huez in 2015 for the tour… love pedals best.

  2. Jon…… Please don't perpetuate the 220 minus your age fallacy. This has NO basis in science. It was invented in the US during the 2nd WW as a short cut to determine fitness of recruits but it has no meaningful reliability. You might just as well use your IQ plus fifty.

  3. Absolute accuracy doesn't matter, i't's all about repeatability. If it shows 500 w on a bad day, and 700 w on a not so bad day, then that's all you need. That those are ridiculously high numbers only matters when it comes to comparing yourself to other people, but for actual training and pacing, absolute accuracy doesn't matter.

  4. I’m using Rotor inPower. I’ve got a question about the optimum chainring position (ocp). Maybe someone knows the answer. I’ve used the Rotor software to determine my ocp. But when I do the ocp test with round rings, it suggests lower numbers (1 or 2) and if I do the test with q-rings on standard ocp 3 it suggests ocp 5 or even more. I asked Rotor and I got no clear answer. Anyway, nice video?

  5. I've got a 2nd gen Stages and it's dropping readings tho it's the 1st time that's happened on them since I initially bought Stages.

  6. I use a power pod. Great little thing. Why don't you ever look at that? Review it with other power meters. Think it's one of the cheapest on the market at £300

  7. My main riding disciplines are downhill and enduro mountain biking so a power meter doesn't seem worth it to me. It's still tempting but it's taking a back seat to other parts at the moment.

  8. i use a stages PM, but the reading is not consistent. i use a garmin 520 and the reading every now and then disapears for like 3-5 seconds and then it reappears for about 5-10sec. is this something i should be concerned with? thanks!

  9. Great piece. Although despite the 5 different types of PM you didn't include a traditional crank spider based system! The PT chainring PM and the stages crank arm system are different from that of course, and both are relative newcomers. I've had several PT G3 hubs and now have a P2M NG. One thing I would say to anyone thinking of buying a PM is that the most important thing is accuracy, or, more accurately (ha ha), precision. 2% might not sound like much, but that's 5 watts or more at FTP and once you start training with power you will realise that a consistent increase of 5 watts in your FTP represents a significant increase in fitness and a significant amount of training. Really, the precisions of the current crop of power meters are only just good enough to be useful (it doesn't help that precsion is rarely quoted by manufacturers or tested, but if a PM is x% accurate it should be at least x% precise). Also, remember in this context that although 1 and 2 are both quite small numbers, 1% is twice as much accuracy as 2%…

  10. 4iiii Gen 1 when they first came out had some minor teething pains, then replaced with 4iiii Gen 2 which has been perfect.

  11. I'm not sure this helped much. All you showed us was that the power meters go up and down at the same time. You do little to explain the 15% difference in the reading between the top line and the bottom line (ignoring the heartrate monitor, which is pretty much just a random line).

  12. I ride with a PowerPod and was disappointed you felt the pedal based system is the easiest way to swap your PM from bike to bike. TBH a full crank is not hard to swap now either if you are pulling the tools out. So why have I gone with a PowerPod? Technically they are superior to all other PMs, but this is just from the perspective on an Engineer with a large degree of experience with military applications using accelerometers. The PowerPod doesn't go out of calibration. All strain gauge systems will need calibrating over time so if continued accuracy for training is key then you need to get calibrations done at least every 12 months. Maybe a tech episode on strain gauges and how they are applied and why they work would be beneficial. PowerPod gives me wind resistance readings that are brilliant to evaluate my performance during a race, looking at the impact of pushing into the wind to move up the peleton or how well I'm drafting are a couple of key areas. Then there is the efficiency measure. Because it is accelerometer based, it maps how much I'm moving my bike around, then averages out the losses during the ride, and shows how I move the bike around when riding so I can focus on improving where needed. I lent mine to a mate and he dropped from 8W to 2W in his losses. Finally, I get left and right power and where the power is being delivered in the pedal stroke.

    PowerPod is a vastly under-recognised meter but I think there is too much data for most riders, plus it hasn't got the cool factor that seems to sell so much product.

  13. 4iiii Innovations Precision left side crank power meter, super happy with it so far and rate it to be better than Stages, having used both extensively for Ultra Endurance training and races.

  14. I'm actually waiting for my first PM to arrive: a PowerTap G3 hub built into the exact wheel set you had on your bike in the video, Jon.

  15. Forever loyal to Quarq pms. Always have, always will. Upgraded my red 22 quarq to the new Dzero. The best.

  16. It should be noted that the P1 pedals require a lithium cell which is harder to get. Put an alkali battery in and you void your warranty.

  17. Very interesting video but possibly more interesting that device-to-device variation would be to see the run-to-run since for training purposes consistency of the data is more important than accuracy, many another video? 😉

  18. Great to see Jonny Tech released into the wild. Stages for me, I just need to be able to measure against myself, so does the trick.
    I get higher max heartrates than Jon's trying to delete my browsing history when I hear her key in the lock.

  19. I didn't hear anything of the first minute because I was too distracted by Jon's sunglasses!!!! Looking slick!

  20. Powertap P1 pedals, I can put 'em on my training bike, tandem, track bike and commuter in a minute, no fuss.

  21. so with all the wireless gear on outdoor stuff, where can we go now to get away from human made radiation ? bad enough that drugs are something so many people do.

  22. Use a hub based power meter, then to raise your FTP by 10w or so, just buy some fancy jockey wheels and new fangled chain lube!

  23. I measure my power output by the amount my crank spindle has bent at the end of each ride. 2cm is a good ride!

  24. Great show! I used a Polar CS600 with Power until I switched to a Garmin with Vector 2 pedals. Being a Mech Eng, I totally geeked out on the Polar Power measurements using chain vibration to measure chain tension. It was unfortunately never accurate during sprint, or on extremely rough roads.

  25. be careful with that chainring power meter. it is a lot thicker than normal chainring and some bike frame may not be compatible. also you will need to find a compatible crank for it.

  26. 1:21 I love my G3 but so many people seem to be hung up on looks. Whatever. I like mine and I'm keeping it.

  27. Start using the Powerpod PM that works completely different from traditional ones. Readings seem to be pretty consistent so far (except in the rain tho I rarely ride in the rain) so for training purpose it's great for the affordable cost.

  28. It is true! Jon does ride bikes!!!
    I train with a Gen2 Stages Power Meter and have had an old PowerTap 2.4 SL hub before that. In all honesty, the Stages Power Meter is a bit irritating because of it's numerous quirks. I had abandon my Garmin forward mount because the distance to the PM would cause dropouts. I have to frequently zero offset the PM, sometimes in mid-ride, because it occasionally goes wild. An, even with all that, it can occasionally dropout anyways!… I'm seriously thinking of going back to the PowerTap.

  29. I'm on a Stages (left only), bought it 3 years ago because it was the cheapest powermeter on the market.
    Been looking to buy a second powermeter for the second bike (gravelracer), i was looking at a Power2Max. The IQ² looks good too (maybe hold out on that one)
    Most important is that the powermeasurement is consistant so you can train within your zones.

  30. I've been thinking of how I could add a power meter to my bicycles and this video helped me to know of option I didn't know about. Thanks

  31. What about a chain based power meter. Measures strain in a couple of links and sends wirelessly to head unit. Let me call the patent office!

  32. Stages dual sided – just finished the TOC holding 80% of FTP! Stops you getting carried away at the start so you can finish strong!

  33. Thanks Jonny Tech, very interesting. As soon as you showed the chest strap I thought "that'll be cobblers", and it is.

  34. I love power tap products but the crankset/spider is due for a new design; it aint very purdy. Just saying

  35. I only train with power indoors as the turbo trainer I have has a built in power meter, its a Tacx Satori, so I am guessing the power calculation from the trainer will be similar to that as from the G3 Hub power meter, or am I way off?Euan

  36. I train with power! I have a left-only P1 pedal. I wanted to switch easily from bike to bike, but my budget wouldn't allow a dual-sided purchase. I wish I could go dual sided, but powertap still don't offer that upgrade yet.

  37. I'm looking to buy a bike with a matte finish. Please help resolve a beer bet I made with my friends. First, are they harder to clean – remove greasy fingerprints after touching chain, spilled energy gel droplets, bug smears, etc. – than glossy finishes? Second, have there been any studies regarding relative drag of glossy vs matte finish, and if so, what di d they reval?

  38. I tried several. Started with a Stages, swapped bike and PM (different crank length) to a Favero pedal based and ended now with a Quarq that delivers much more reliable data. I think in the future I will install Quarq.

  39. Errr… sorry to mention it… but you seem to have forgotten crank based power metres. SRM, Quarq, Pioneer, Power2Max, FSA? Remember them? They all measure power in the crank spider, which I’m pretty is universally accepted as the best place to measure rider power output for accuracy and consistency. Strange omission.

  40. Vector 2 pedals and Garmin 510 on the road. Inside I use Taxc Neo and trainer road for structured training plans

  41. I'd have liked to see what sort of results you would get by intentionally cross-chaining. Curious if that would make the chainring meter read high due to sideways load, and the hub meter read low due to extra drivetrain losses.

  42. I was doing a test run with garmin pedals 3, upon return, the store told me the price, i nearly fell off my bike, so I decided that power meters are not safe for me to use.

  43. I test custom made power meter which additionally tells me what gear selection will be best to keep given power as well as shows future terrain slope prediction based on elevation data available so I know what to expect next. That is is why I'm not interested at buying any known cycling power meter on the market, no more since my home made power meter for road cycling is better integrated with also custom electronics gears change & suggestion system 😉

  44. I have a powertap wheel and a stages left crank power meter. Their readings are virtually the same. Changing batteries is much easier on the Stages. Changing crankarm from bike to bike takes a few minutes, but not so bad- IF bikes have same crank system

  45. Basically I had to basically stop watching this video because basically the over use of basically the word basically.

  46. One of the biggest follower of GCN here, for years, disliked my first video ever. Only power tap and stages? I get it that its sponsored, but leaving all other power meters, not a good job sir.

  47. Hi GCN, Great videos i general and in articular this one about PowerMetres. Can you say what is the approximate difference in percentage between :
    – the 3 average of the 3 PowerCal power metres
    – the calculated data from heart rate

    As the Hub, pedals and ring methods seem to be very very close one to another, there is not much deviation. Knowing the accuracy (and perhaps delay) with the Heart Rte based model can help those – like me – without a power metre. Are we talking 10%? 20%? 30%? difference ?

    looking forward to hearing from you.
    Kind regards, Lionel

  48. What a coincidence. I just bought one of these chainring power-meter from power-tap last week! They're an absolute bargain at $350 (for dual-side power)

  49. interesting vid Jon! Now that you're done with this it seems you are stuck with 4 extra Bolts and I do not mind holding on to one of them for you…

  50. c1 chainrings VERY sketchy. dont like the wet even though the battery compartment is enclosed! I have them and they eat batteries. ok but not great!

  51. A carefully worded script from 0:12
    Training with power has become one of the most torqued about ways …

  52. I had power tap this year with pedals and I've had so many issues with them. Like eating batterys like it's candy. I'm moving to quarq crank power

  53. I use an SRM on my tri and love it. I also have PowerTap pedals on my road bike. I find both are consistent as compared to a computrainer reading. In general, and I am confused by this, the pedals give a slightly lower, about 5%, reading than the other two. CT and SRM are within 1%. I would expect the pedals to give a higher reading because of loss in the drivetrain. However, the numbers are all consistent, i.e. the 5% difference remains essentially constant regardless of the power.

  54. I train with Garmin Vector 2, my mate has vector 3 they should be better as no need to fit with torque wrench making it easier to switch between bikes. Also no external pod to get knocked about on the vector 3, very tidy. After a few months his vector 3's started giving wild readings. Garmin say the internal battery pod design was wrong and they are addressing it. Lesson for me was don't be the first to by new tech!

  55. With units like Watteam changing the power meter space from a price perspective it really is time to get in to power based training.

  56. A few month back, I gave iQSquared a early chance over on a social financing platform for the development of their new product: a cheaper yet effective power meter. You must know of them. According to their follow up emails, everything seems to be on plan, with first units to be released in Sept. Fingers crossed ! Hopefully, you will do a review then, but maybe you could even attempt an approach now since they are so close to D day.

    Nonetheless, thx for this great —as usual— video on PMs.

  57. I use a power tap C1. Very happy with it. Much better training tool than just relying on heart rate I think. Love the show 🙂

  58. i train like Eddy M.

    i can't justify the expense of an overpriced product. i do fine. i think it's a marketing grab and could easily be cheaper. also, i like my bike as is and do not want to swap to a proprietary system. power is power so why all the different price points and methods etc. ?

    get it right, make it universal and then you can have my money.

    i prefer to invest in food and time

  59. Train with heart rate, never get above my aerobic heart rate. Power is only a result of good training, training with power is like taking ibuprofen gel for knee pain instead of looking at potential sources of pain.

  60. riding around with all those Wahoo Bolts is like having the Post Office tower strapped to your handlebars! I kinda like it though…

  61. Absolutely, using TACX Neo indoor with The Sufferfest training and using Favero Assioma Duo on my Specialized Tarmac. Using a Wahoo Elemnt as my head unit.

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