Bluetooth, I apologize

Why I've changed my mind in the Bluetooth vs. ANT+ debate

While French and English are the common languages of road racing, ANT+ and Bluetooth are the two ways bike parts talk to each other. In the not-too-distant past, I cast my vote for ANT+.

Well, after spending way too many hours arguing with power meters, Garmin head units, smart trainers and computers, I stand here with cycling hat in hand. And I would like to say, I am sorry, Bluetooth; I shouldn't have spoken ill of you.

A brief history of ANT+: from garage to Garmin

The ANT+ wireless frequency is ubiquitous for cycling devices. At Interbike this year, I enjoyed talking with one of the creators of ANT+, Victoria Brilz, who is now running 4iiii with her husband, Kip Fyfe

In 2003, they created the low-power protocol to use with Nike foot pods for transmitting data to running watches. After Garmin saw the promise and purchased the company in 2006, ANT+ blossomed into the de facto standard for speed/cadence sensors, heart rate monitors, power meters and, certainly, Garmin Edge computers and other products.

The great thing about ANT+ — and why I initially endorsed it over Bluetooth — is that it works across so many platforms, brands and products. All too often in cycling, one man's integrated is another man's incompatible, and a plethora of 'standards' means many products just won't work with others. With ANT+, you can mix and match, and the stuff simply works.

One-to-one versus one-to-many

One fundamental way ANT+ and Bluetooth differ is that ANT+ can be used to connect one thing to multiple other things, while Bluetooth is a one-to-one connection for each type of thing. For instance, you can connect your ANT+ heart rate monitor to four different computers at once, or four heart rate monitors to one computer (although you'll have to pick which one's data you see). With Bluetooth, you can pair one heart rate monitor to one computer. If you want to use another computer, you'll have to disconnect the first one.

For most of us, this doesn't make much difference either way. We will just connect a sensor to our bike computer and be done with it. 

The only frustration I have with this protocol involves our little Bose Bluetooth speaker at home. When I want to play music, I have to track down my wife's phone and disconnect it before I can connect mine. That's annoying. But that's not cycling...

My initial cycling complaint with Bluetooth was that so few companies used it. And when they did, like Polar and Look, they used it exclusively instead of ANT+, so that you had to buy into the whole system.  (Look changed this in 2015.) 

What changed? Auto uploads, on-computer alerts… and Zwift

As 2017 draws to a close, it's a lot easier to find wireless cycling products using Bluetooth as well as ANT+. Stages kicked off the power-meter category with Bluetooth/ANT+ transmissions, and now-dual broadcast is the standard for smart trainers. 

Of course smartphones have long offered Bluetooth, and many newer laptops have it, too. The new Android Galaxy 7 (not the exploding one — the other one) is cool with its native ANT+, which I've been testing with TrainerRoad. But short of that, getting ANT+ to talk to your phone or computer requires a plug-in dongle or USB stick. Not very slick. 

Having your Garmin Edge or Wahoo Elemnt computer paired to your smartphone is cool for two reasons: auto uploads of rides to Strava and elsewhere without taking your computer off your bike, and the ability to see incoming texts and calls on your computer without taking your phone out of your jersey pocket. 

A drop means getting dropped

But the thing that has really made me a believer in Bluetooth is indoor riding. Sometimes power meters or smart trainers just don't communicate perfectly with head units or computers on ANT+, in that there are short drops in power data sometimes. It's usually impossible to determine whether it's the meter/smart trainer or the head unit/computer losing the signal. (Stages and Garmin were each arguing their side of the story on this subject in a story I wrote during the Tour de France about Chris Froome's bike.) 

Whatever the cause, when riding outside, it doesn't really matter if your power readout goes to zero for a second or two. But when riding inside, a power drop can fundamentally change your experience if you are doing a virtual ride or race, as everything is power-based. On Zwift, if your power goes from 300w or whatever to 0w for a few seconds, you get dropped. Simple as that. 

Here a Bluetooth signal in boldface and an ANT+ signal in lighter green record from the same Elite Direto ride. Note how the ANT+ signal drops in a number of places
Here a Bluetooth signal in boldface and an ANT+ signal in lighter green record from the same Elite Direto ride. Note how the ANT+ signal drops in a number of places

In the process of testing 10 smart trainers and new power meters from Shimano and Garmin, I've spent way more hours than I should on Zwift this fall. And I can't tell you how many times in group rides or races someone has complained about their signal dropping out. 

Initially, I just kept a USB dongle in my MacBook Air to use with trainers and power meters. But this year I've just used Bluetooth, and have had zero problems across 10 trainers.

In recording data for the smart trainer test, I used Garmins for each trainer and the two power meters I used concurrently. I had good luck with the Edge 1000 and the new Edge 1030 units. But the Edge 820 unit proved itself inadequate as a comparison tool because of so many drops.

To be clear, not all ANT+ signals are created the same. Some meters, some trainers and some head units are near flawless. It's just my experience that Bluetooth is generally better at keeping a steady power signal. 

So what to do?

My advice is simple: use Bluetooth any time you're riding indoors. When considering buying a new gadget, go for something with ANT+ and Bluetooth. You won't regret having options.

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