Tech Breakdown – Wahoo Fitness’ Smartphone Powered Cycling Trainer & Computer
After releasing two sweet new electronic training devices in the last couple months, we caught up with the folks at Wahoo Fitness to get a bit more info. Mike Stashak, VP of Marketing & Sales, and Molly Andruszkiewicz, Wahoo’s marketing director, gave us the run down on their technology.
They launched the Kickr trainer at Eurobike and the Rflkt cycling computer at Interbike. The trainer uses a heavyweight (12.75lb) flywheel for lifelike road feel with electromagnetic resistance added for adjustability. The computer mirrors the data captured by their iPhone app and lets you control some settings and external-to-the-app things like music while your phone’s safely tucked away in your jersey or pack.
Click on through to see how it all works…
The Kickr is on schedule for a January launch. Retail is set at $999, and even they’ll admit that’s not cheap. But, when you consider it has a real power-measuring strain gauge, the combo of Bluetooth Smart and ANT+ and a Gates belt drive on a chassis that’s very adjustable, it at least makes sense.
The API for the trainer has been released, and Stashak says TrainerRoad.com and KinoMap have apps ready to go. As mentioned at Eurobike, Strava compatibility is being worked out. Hobbs says they’re on board, they’re just working out the details on how to post indoor data versus real world data for a given route or segment.
In addition to simulating rides, it can also be set so you maintain a constant power output or constant conditions. The two modes are Ergometer and Slope:
- Ergometer Mode: This mode dynamically adjusts the torque to maintain a constant power regardless of speed or cadence, making it great for interval training.
- Slope Mode: This mode you set the rider/bike weight, Coefficient of rolling resistance, Coefficient of wind resistance and grade. Based on these inputs, it’ll continually calculate the power for the current speed. These variables can be adjusted as often as 4 times per second, to simulate changes in road condition, rider position/drafting, and most importantly current grade.
To control the resistance, more or less power is pumped to magnets on a fixed block of aluminum inside the flywheel. Shown above, six magnets are placed such that the flywheel rotates around them, just half a millimeter off their surface. The app controls how much power is put to the magnet. More power creates a stronger pull on the flywheel, equaling greater resistance. If you don’t connect any display (i.e. An iPhone) to it, it’ll simply provide progressive resistance like any other trainer.
The magnet’s alloy base sits on bearings, but doesn’t rotate. The power meter strain gauge holds it steady, and it’s the resistance from the magnets wanting to rotate with the flywheel that’s being measured and calculated into your power output. The flywheel is the outer part you see with the white chevron arrows…that’s not just a cover, it spins.
Stashak says this is the first product to offer dual transmission of Bluetooth and ANT+. He said by the end of 2013, you’ll see more manufacturers building dual transmitters into their devices, but they didn’t want to wait. It’s 100% their design and they included the protocol into the Wahoo API for Apps to connect to it. The only other dual transmission product in the market is the Stages power meter, which also uses the Wahoo API.
Why not build in dynamo power so you could use the trainer without plugging it in? Stashak says because adding a regenerative braking system would have thrown off the power measurement to about +/- 6% to 7%, and they wanted it as accurate as 2-3 watts. Not 2-3% mind you, 2-3 watts. It also would have made a loud, annoying hum.
The Rflkt is also targeted for a January 1st release. The computer is essentially a slave monitor with some controls (see how it works in our video from Interbike). You’ll need to run a compatible app, which can collect data from GPS, speed/cadence and heart rate sensors and any power meters that can send data in either Bluetooth Smart or, with a dongle for your phone, ANT+. Your iPhone 4S/5 remains the brains of the operation, the Rflkt simply shows you the info and lets you control it remotely.
What’s really cool is that someone could build an app (Hello, developers? Pay attention here) to connect to the Rflkt and integrate maps and turn-by-turn navigation or anything else that your iPhone can do. The only catch is that the computer will only display/control one app at a time, so whichever app it’s synced to should have the functions you want to see while riding. The apps can also pull in ANT+ data if you’ve attached a dongle to your phone. At launch, it’ll be compatible with Wahoo’s app and Cyclemeter’s, but they said plenty more are already working on things.
As for Android devices, those devices have not adopted either low-power data transmission technology. Stashak: “We see several new models coming out with Bluetooth Smart soon, and we hope to work with the handset manufacturers to access the technology in the phones so our equipment will work with it. We anticipate the Android OS coming around eventually, but Google has to say they’re ready to adopt it. In the meantime, we’d have to build device-specific apps and we’re not there yet.”
“We’re just a bunch of folks that love to ride and run, and we always have our smartphones with us,” said Stashak. “Wahoo let us bring it all together, and that’s where we’re putting our energy. We’ve got a couple of things in the cycling space we’re working on for the next six months, and we’re doing a rethink of the heart rate monitor strap, too. But that’s really all I can say for now.”