Full disclosure: Every powertap hub I’ve ever owned has been purchased with my own money and I’ve never been sponsored by them. SRAM is a sponsor of my O2 Racing team and supplies us with Quarq CinQo powercranks. I am under no obligation to write this article however.
The Powertap and the CinQo Quark are the two leading brands in the powermeter industry (barring SRM) and I’m glad I’m in a position to have used both of them. I’ll refrain from doing a side by side spec comparison. You can find that in lots of places. I’ve ridden on both of these powermeters for tens of thousands of kilometers and will tell you my personal experiences with them and what I think. There’s a lot of information and I could ramble on forever about this topic, but I’ll try to keep it brief and to the point.
I’ll start by pointing out the obvious. The CinQo (made by Quarq sold with SRAM Red Chainrings and crank arms in Australia) is a crank based powermeter. I personally find their branding a little confusing, but it’s commonly just referred to on the street as “the Quarq”. The measurement instrumented is called the crank “spider” that mounts to the crank and chainrings. The spider calculates power by measuring the torque (pedal force) and the angular velocity (cadence). Strain gages are used to measure the flex that the pedal forces produce and can calculate the applied torque.
The powertap is a hub based powermeter which uses the same basic strain gage technology to measure torque, however it is measured at the hub instead of at the crank.
In my experience there are pros and cons to both systems.
Powertap Pros and Cons
PRO The Powertap needs a wheel built up around it, but in the end it’s still cheaper than the Quarq if it’s built with a decent training wheel. Of course you could increase the price dramatically by getting it built with a Zipp 404 if you so desire. The hub comes in multiple spoke hole counts (20, 24, 28 or 32) so there are many options if you want to customise it to your own wheel specification. To save the hassle, I’ve always purchased my Powertaps along with the wheel. It’s much more inexpensive than sourcing your own spokes, rim and getting someone to build it up for you.
The most basic Powertap model (the Powertap Comp) is a wired version, but every other model above it is wireless. With the wireless models, you basically install a cassette and tyre and you’re ready to roll. The installation is dead simple. All you need to do is pair it with the head unit, calibrate the readings, and you’re done.
CON You cannot measure power when you want to swap to another set of wheels. The common way of building up a Powertap is by using a DT Swiss or Mavic rim which makes it perfect for a solid training wheel. However, it’s not overly light or aerodynamic and doesn’t make for an ideal race wheel. Then again, a powermeter isn’t overly useful when road racing. It’s basically an expensive speedometer when the pace is being dictated to you. Time trialling is a different story however. Having a powermeter to pace yourself during a ITT is an invaluable tool.
Head Unit Devices
PRO The Powertap (certain models) is ANT+ compatible which allows your data to be displayed on any ANT+ capable head unit (such as a Garmin device). Powertap however gives you the choice of two different of head unit options:
I have lots of experience with the “Cervo” and have to admit that Powertap could do a better job at the user interface with this model. Once everything is set up it’s fine, however if I want to change anything or calibrate the powermeter I need to go to the user manual every time. Navigating the through menus takes a bit of time and patience. However, the display is large, clear and well thought out and the battery life is excellent.
I’ve only used the “Joule” over a one week period but I can definitely tell you it’s much more user friendly. The display is larger with and can give you some great real-time stats and power specific readouts (such as TSS for you power-junkies out there). There is no GPS incorporated into either of these head units, but elevation is measured and recorded.
From what I understand, even though the Powertap Cervo head unit has an ANT+ interface, it is not compatible for use with other powermeter brands. However, The Powertap Joule 2.0 does work on other powermeters (such as the Quarq).
Powertap also gives you the option of purchasing the hub without the head unit. You can use a Garmin (310XT, 500, 705, 800), SRM (PC 6 or 7), or even an iPhone with a ANT+ dongle. Whatever your fancy.
Downloading Data and Software
The Powertap head unit connects to your computer via USB and is very well integrated with it’s intended software called “PowerAgent”. I’m very familiar with PowerAgent and have seen it progress over the years. Personally, it’s my preferred power analysis software simply because I’ve been using it for so long and I like the functionality.
However, neither of the Powertap head units are tied to the PowerAgent software and you can use anything you like to upload and analyse your data (Training Peaks, Golden Cheeta, etc).
There is very little to do with the Powertap in terms of maintenance. There is a battery that sits inside the hub which is easy to change. If you use the proper batteries (lithium, not alkaline) they’ll last a few months (this depends on how often you’re riding).
I calibrated my Powertap once every weeks or so, but it was very quick and easy. Outside temperature variance is one of the biggest reasons to calibrate a powermeter often.
I’ll be honest by saying that I’ve had to send back one of my Powertap hubs for warranty replacement after a year of use. The distributer was very accommodating to me and I had no problems getting warranty. However, my one warning is that I had to spend another $400 to get a new wheel built up around it (new spokes, new rim and labour).
Warranty for the Powertap in Australia is one year on all electronics, and lifetime on the hub itself.
Powertap has many models and options. Hub only base price is $799 and can go up to $1799 (with wheel build, without head unit). You can get a perfectly good Powertap hub (PRO+ model) built up with a wheel for $1199.
Quarq Pros and Cons
PRO I’ve been using the Quarq for over a year now and I have to say, I love it. I can swap over wheels whenever I like and still have a powermeter, there’s no noticeable weight difference, and installation and maintenance is easy.
The Quarq comes with options for compact chainrings (110 BCD) or regular chainrings (130 BCD). You also have the option of the regular English threaded external bottom bracket (GXP) or the BB30 style bottom bracket. Mine above is the BB30 model (you can’t see the difference).
CON I can’t think of a con with the Quarq except for the price (when compared to the Powertap). On that note, the Quarq is both a crankset and a powermeter. Much of the cost is encompassed in the SRAM RED cranks, chainrings, and bottom bracket (which you need on a bike anyway). If you’re looking for an SRM alternative, then the Quarq is relatively inexpensive. It depends on your perspective.
Head Unit Devices
The Quarq does not come with a head unit. I don’t see this as a PRO or a CON. The Quarq is ANT+ compatible and as said before, will work with devices such as Garmin (310XT, 500, 705, 800), SRM (PC 6 or 7), or even an iPhone with a ANT+ dongle. I highly recommend using a Garmin 500 or 800 paired up with the Quarq. They don’t have the same power specific functionality built into them as the Powertap Joule, but have pretty much everything you need.
Downloading Data and Software
My only small complaint with using these Garmin devices is that many power analysis software that I’ve tried do not allow you to upload the GPS data files in one clean easy step (except for TrainingPeaks, but they don’t have a Mac version and I haven’t been tempted to use their web version). I’ve been told that Golden Cheetah 2.0 will directly upload Garmin FIT files (I have yet to try this). This isn’t Garmin’s fault however. Services like Strava do a fantastic job at uploading and displaying all your GPS data, but they are still working on more power specific analysis and functionality (in this regard they are much better than Garmin Connect).
As with the Powertap, there is very little maintenance involved with keeping the Quarq running smoothly. There is a small battery that is easy to replace (the battery sits under the “Q” in the Quarq photo above). The battery is inexpensive, can be bought anywhere, and lasts for months.
Quarq recommends the unit to be calibrated before every ride. I calibrate mine once a week and the process is very simple.
With regards to warranty, I have to admit that I had a few growing pains with my Quarq when we first received it last year. I had to send one back, however it was replaced promptly without any issues since. Since then I’ve received my new Quarq and it’s been working flawlessly. The spider unit is the piece that will need replacing if there are problems with power measurements and it is relatively inexpensive to replace.
Warranty for the Quarq in Australia is two years.
Sold in Australia for $2299.95 (no head unit).
Other Powermeters On The Market
There are a few other powermeters on the market that I don’t have experience with, but will describe them briefly:
- The iBike is relatively inexpensive compared to other powermeters. It calculates power based on multiple variables and I’ve heard good things about it.
- I love Polar’s products, but I haven’t heard too many positive things about their power measuring approach which uses chain tension and chain speed to calculate power. Their accuracy problems may have been rectified, but I have not been able to find out anything about this.
- SRM is considered to the the gold standard of powermeters which all the PROs use, but I can’t even consider looking at them because of the high price.
- I’m very keen to try out this new pedal axel based powermeters from Metrigear called “Vector”. From what I understand there will be a Speedplay version of this pedal which is ANT+ compatible, and LOOK will be making a pedal compatible with Polar’s head unit. Garmin has recently acquired them and I think we’ll see some great things to come if the $1000 USD pricepoint is achieved.
The Metragear Vector pedal-based powermeter
Both powermeter manufacturers claim to be accurate within +/- 2%. To me, accuracy isn’t a big issue. I just want it to be consistant with itself. I’ve never noticed any inconsistant readings with either of the powermeters except for times that I haven’t ridden it for a few weeks and forgot to calibrated it.
If I were to purchase either one of these powermeters and I had $2300 burning a hole in my pocket I’d recommend the Quarq. Unfortunately I don’t have that much money kicking around and I can’t afford spending that much on a powermeter. In real life, I’d buy the Powertap because of the very reasonable price points (you’ll save $1000 if you don’t go nuts with the wheel build). The main benefit of having the Quarq is that you’re not restricted to a specific wheel choice. In reality, a powermeter is a training tool more than it is a racing tool and I’m not too fussed about leaving it behind for races.
In either case, keep in mind that on any bike you need a rear wheel (Powertap) or a crankset (Quark) and you have to sink some costs into those components anyway. Yes, both are pricey, but the incremental price for a powermeter is not quite as expensive as it sounds at first.
If there’s one piece of advice I can give, it’s this: Don’t buy a powermeter over the internet because there’s a reasonable chance you’ll need some local support to get it fixed or replaced. Powermeters contain electronic parts that are moving and are heavily abused. They’re made to last, but problems can occur and I’m happy with the local support I’ve had here when problems arise.
Do you need a powermeter? Well, not really. I love having one and it’s changed my whole perspective on training, but if you don’t take the time to understand how to use it, you’re probably wasting your money. Every single powermeter sold should come with the book Training and Racing With A Powermeter by Allen and Coggan!