What's Cool In Road Cycling

PowerTap G3 Hub & Joule GPS Review

Power monitor options for cyclists continue to expand. One company that has stood the test of time has been PowerTap, which has been making hub-based power measurement for over a decade. PowerTap has continued to innovate, and we’ve had a chance to put their latest G3 hubs and Joule GPS computers through their paces.

Since their introduction in the early 1990s, power monitors have supplanted heart rate monitors as the ultimate measurement of choice for cyclists interested in the most efficient path to smart training and improvement. This article isn’t meant to be a “why training with power is great” type. If you’re reading this, you already know it’s the way to go for smart and efficient training.

The sleek new Joule GPS also includes sleek new gps tracking, and mates perfectly with the newly designed PowerTap G3 hub…

But with the burgeoning market and availability of choices, the important question becomes:
1. Is PowerTap the right tool for me, and
2. Is the G3 worth the upgrade from previous versions?

My History with PowerTap
I’m on my third generation of PowerTap wheels now with the G3. My 2006 wired Pro SL is now on my fendered training bike and continues to work perfectly fine. Admittedly, being laced to a nice set of Zipp 303 clinchers, it was my top set of wheels for much of the past five years, so I haven’t exactly pounded the heck out of them. Regardless, I’ve never had any mechanical issues with the hubs or the electronics. Battery changes have been simple and straightforward, and the bearings still run nice and smooth with minimal maintenance.

Most of us have moved on from the wired world, however, so the better basis of comparison would be with my PowerTap Pro SL wireless hub, which I have been bashing around across the world since fall 2010. Laced to a set of DT-Swiss 465 rims, it has been my main set of wheels these past two years on all of my bikes. I have also been training and racing cyclocross with it for a full season in 2010 with no issues.

This certainly highlights the versatility of the hub-based PowerTap compared to crank-based systems, as swapping wheels across my 3 road and 1 cyclocross bikes is pretty much beyond simple. As a result, I’ve had the benefit of detailed power analysis for >90% of all my rides throughout this time.

The wireless PowerTap has worked flawlessly for me the past two years and throughout my sabbatical, which involved about 10 separate times packing everything into my Ritchey BreakAway box and a fair bit of getting soaked in pouring rain in the Netherlands.

Worth the Upgrade?
At its core, the G3 retains the same strain gauge quality and quantity, consisting of 4 pairs of gauges within the hub. The transmission rate is also as good as before at 1 s.

So the obvious question arises of what the difference is between generations, and is it worth it to: 1) upgrade if you already have an existing PowerTap, and 2) buy a G3 new versus perhaps a used older generation PowerTap?

In response to both scenarios, that is of course partly on how much you want/need the latest and greatest, and what price you might be able to get a used PowerTap for. The G3 is definitely not a case, however, of a simple marketing move to call something with new decals or colours new.

Some of the distinct improvements with the G3 include:

• The hub is completely re-engineered to move the electronics (antennae, transmitter, processor) from the hub to the end cap. In prior models, the end cap was a simple plastic covering, and all the electronics and transmitters were built into the hub itself. By necessity, this made the actual hub body thicker. Most importantly, if anything went wrong with the electronics, repair or replacement would involve sending away the entire wheel.

The antennae, transmitter & processor have been smartly placed into the hub end cap, making servicing much easier.

• With the G3, the strain gauges and the main board obviously remain locked up inside the hub, but they’re generally not what would fail. Most of the time now, servicing of the G3 electronics involve simply removing and mailing away the small end cap, a significant savings in postage and also potential wheel damage from shipping. There is also a mini-USB slot in the end cap, permitting future firmware upgrades to the electronics not possible before.

• The rear hub weight is significantly dropped by 80 g, down to a claimed 325 g (we got the complete wheel, so don’t expect me to verify this by cutting the spokes of my wheels!). This puts the G3 in line with most top-end rear hubs, finally putting to rest any concerns over sacrificing extra weight. Realistically, being located in the hub (rather than the rims) and low on the bike anyway, that weight worry was never a concern for me anyway.

The hub flanges have been widened, adding stiffness and durability.

• The G3 has wider flanges (38.0 mm versus 31.7 hub centre to flange on the non-drive side) than prior models, which theoretically makes for a stiffer and more durable wheel. I couldn’t fairly test this out on the road, as my previous PowerTap was an alloy (DT Swiss) wheelset that has been pretty hammered with cyclocross use and a full 15 months of constant packing and lots of Belgian cobblestones during my sabbatical. There’s no doubt though that the G3/Enve combination is incredibly stiff laterally, as I couldn’t produce any brake rub even sprinting with the pads set extremely close.

• The G2 and G3 both can be paired with cadence sensors, or alternately provide a built-in “virtual” cadence based on the periodicity of power fluctuations over the pedal stroke. It’s impossible to directly test the virtual with an actual cadence sensor.. However, my personal observation is that the G3 virtual cadence is more robust and accurate, specifically being less prone to wild fluctuations. Riding along at a steady clip, there’s much less wild swings upwards or downwards with the G3. This is likely a result of their engineers developing improved algorithms, and also an example of the potential for firmware upgrades now possible with the G3.

Being hub-based, one huge advantage for PowerTap is the ease of swapping wheels across multiple bikes. MUCH easier than swapping cranks any day of the week. My Pro SL has seen plenty of time on three different bikes. I also have an eclectic mix of components, from SRAM on my cyclocross bike, Shimano on my BreakAway, to Campagnolo on my De Rosa. So in addition to the overall ease of swapping wheels across bikes, one little thing that I’ve greatly appreciated is the ease of swapping freehub bodies on PowerTap wheels between Campy and Shimano/SRAM. The dead-simple swap system has been retained for the G3.

Changing hub bodies is simple. Take the cassette off, and then just pull out the freehub body and push in the other one. Your hands are the only tools required.

PowerTap G3 Hub Summary
From a very pragmatic perspective, the best power monitor is the one that you have on your bike! So if you do have the opportunity to get a good deal on a G2 hub, I don’t think you can go wrong, especially for a set mainly used with training or cyclocross.

Like I’ve written so far, I’ve found all of the various generations of PowerTap hubs to be completely resolute and reliable. However, I have had riding buddies who have had problems of one kind or another with their systems. Therefore, the ease of servicing for the G3 can be a big benefit.

Beyond the electronics servicability, the G3 has big upgrades in weight and in the potential for wheel stiffness, making them very worthy of consideration, especially as the price upgrade isn’t overly steep.

CycleOps has added a thorough lineup of wheelsets already paired with the G3 hub. Our tester was the 45mm all carbon clinchers, made for CycleOps by Enve.

Joule GPS
The Joule computer has also undergone a thorough redesign from the original Joule 2.0 that I’ve been using since 2010. We’ve reviewed the 2.0 before and I pretty much echo Jered’s take on the 2.0 – it’s a very nice design and has pretty much every feature available that you can ever imagine or imagine desiring.

The one major no-show to the Joule 2.0 was GPS, and that’s been rectified by the Joule GPS (there is also a new non-GPS Joule with every other identical spec though for a cheaper price).

The new mounting arm makes allows for a more ‘aero’ look, and an option if you like riding with two computers.

Some folks I know have complained about the looks and the size of the Joule 2.0, which I just don’t understand considering the size of the iPhone or Garmin 800 they’re willing to slap on their stems. Regardless, to appease these fashionistas, the Joule GPS has been given a complete makeover, reducing the “yellow-ness” of the computer and looking more “carbon” instead. The Joule GPS is now almost all black except for subtle yellow highlights and a yellow bottom, and the corners and edges are more curved and rounded than the rectangular and boxy look of the Joule 2.0.

The Joule GPS looks great – no doubt about that. One thing to keep in mind though is to take a bit more care about tossing the computer into your travel bag. Due to the rounded design, the plastic screen is a bit more exposed and liable to scratch than the recessed screen in the Joule 2.0 design. My Joule 2.0 has been fine over two years now, but the Joule GPS developed a few minor scratches within a month of use, most likely from tossing it into my gear bag travelling to races. A microfiber bag like those with sunglasses would make a good protector.

Previous PowerTap computers have all relied on direct, zip-tied mounts to the stem or handlebars, and there is one of those with the Joule GPS too. However, I especially love the new mount that places the Joule out in front of the stem and handlebars. Besides giving it a modern look, it also gets the computer out of the direct line of fire for sweat drippage on the stem.

The optional ‘ahead-of’stem’ mount is dead-simple to swap across multiple bikes, requiring a Philips or flathead screwdriver and 30 seconds, plus the Joule GPS snaps right in.

If the Joule 2.0 was a lot of information, the Joule GPS goes a few steps beyond information overload. The Joule 2.0 has a single dashboard of 6 different performance metrics, with the highlighted metric having two additional smaller data displays at the bottom (e.g. highlighting power also gives you average and max power). What shows up in the bigger dashboard screen can be rotated between the three data points. And from the PowerAgent software, you can customize what six metrics you want to see.

With the Joule GPS, you have five different dashboards you can select to view, with each dashboard fully customizable. There is still the same “6 metric” main dashboard, but also a “4 metric” and “3 metric” dashboards. You can also customize these dashboards to have 3-6 metrics on display. This is followed by the “intervals” dashboard (also available on the Joule 2.0) and a final GPS dashboard with 2 metrics on top. From PowerAgent, you can configure which metric (of 35 potential ones) you wish to have on each dashboard.

The overload of info is certainly terrific, but it’s definitely one of those things you should avoid fixating upon while riding. I’ve personally come to prefer the “3 metric” view, with a very large power data on top and my choice of two other metrics (usually speed and ride time) on the bottom.

One Joule 2.0 feature I miss, however, is the ability to rotate amongst the 3 different data within one metric (e.g. power, average and max power) to show up on top. For example, when doing intervals, I like to keep my eye on average power (and the road of course!), and wish that it could be the big number up on top of that 3 metric view.

The mini-usb connector is safe from the elements behind a rubber tab.

CycleOps has also done a nice job in the human factors design of the Joule GPS. For instance, the interval button for setting new laps or swapping to interval mode (seeing the specs for that particular lap) is the only button on top of the computer, and is usually the main one that you’re touching regularly during a ride. That eliminates confusion and the bigger button makes it easier to operate with gloved fingers.

There are three other buttons for scrolling and setting data set off on the sides of the Joule GPS. These are also big for easy operation, but don’t “look” big by being black like the computer itself.

The Joule GPS, as stated in the name, has addressed one of the perceived limitations for the company’s computer offerings compared to its competition. GPS is now available, the design is modern and attractive, the data available for real-time view is stupendous, the mount is better, and the price has dropped from the Joule 2.0. What else could you seriously want in a computer upgrade?

• See the CycleOps Website

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