The £115 Wahoo Fitness RFLKT Computer is unique in that it relies on an iPhone for all of its data - it pairs with an iPhone 4S or iPhone 5 via Bluetooth for all of its functionality. As a result, it gives you access to smartphone features that other bike computers don't offer, most notably the ability to switch your iPhone's music tracks wirelessly. See also: iPhone 5 vs iPhone 4S comparison review.
Specifically, the RFLKT is designed to interact with Wahoo Fitness's iOS app, which tracks your workout time, distance traveled, and speed; it can also connect with other sensors over Bluetooth to display your heart rate, cadence, calories burned, and more. By displaying all your ride data on the app, the RFLKT essentially turns your phone into a powerful bike computer capable of giving you a great deal of information.
And if you prefer to use another biking app such as Cyclemeter, you'll be pleased to learn that Wahoo Fitness says compatibility with the RFLKT is on the way for that app, as well as for Strava and others. (Currently the RFLKT is also compatible with version 3.0 of Wahoo Fitness's App for Cycling). See also: FitBit Zip review.
Wahoo Fitness RFLKT Computer: Information is power
The RFLKT is a rectangular device slightly smaller than a box of Tic Tacs, with four raised buttons (two on each side) for operating the menus and controls. Weighing 6g, it measures 61x41x13mm. The back slides into a panel attached to an O-ring, which fits around either the stem or the handlebar mount on your bike.
The screen of the RFLKT is a monochrome LCD that measures roughly 1.75 inches by 1.25 inches. You can customize the screen to display the data you need most, just as you can customize which functions the buttons control. The RFLKT can access features of paired apps, or control functions on your iPhone (including music playback).
Because the RFLKT operates over Bluetooth, your phone (or iPad) must remain within about 5 to 10 feet of the device, which I didn't find to be a problem. To attach the RFLKT to your bike, you use the included screw to hold the O-ring in place, which is easy enough.
However, although you can keep the mount attached to your bike at all times, you probably won't want to leave the RFLKT in the mount, as it would make a mighty attractive item for thieves--who could easily remove it by prying it out of the back panel. This means you'll need to remember to bring the included "key" (read: metal stick) to pry out the RFLKT when you leave your bike unattended. A slight problem to have, but one worth noting.
To test the RFLKT, I attached it to my bike using the gadget's included handlebar mount and took off from my Berkeley, California, apartment for a ride through the city's bicycle boulevards and hilly neighborhoods.
Since I didn't have an additional peripheral device for measuring speed, I had to rely on my iPhone's GPS to measure how fast I was moving, which produced a few hiccups. While it was mostly accurate, I glanced down at the RFLKT's screen a few times to see that I was supposedly traveling at near-freeway speeds--I ride fast, but I'm not Superman. Although that wasn't a huge issue, the blips in speed readings did throw off my workout's top-speed measurement in the app, which was a bit disappointing. To measure speed accurately, you'll need an additional peripheral device.
Wahoo Fitness sells a speed sensor called the Blue SC that works with the Wahoo Fitness app to provide cadence and pedal-power data. Additionally, Wahoo makes peripherals that include sensors for measuring heart rate and stride, among other things. These sensors, designed to enhance the app's capabilities, in turn enhance the RFLKT--essentially, since it is an extension of your iPhone, the RFLKT is only as powerful as the data fed into the app.
Even though my lack of additional Wahoo peripherals left a few blank data sections in the app, the RFLKT's exceedingly customizable interface made it easy to display only the information I had available on my ride. By creating custom page layouts within the Wahoo Fitness app, I was able to select the data I wanted to see. For example, I made two screens: one displaying my workout time, my speed, my max speed, and the currently playing track's title, and another showing the speed in larger text along with my iPhone's battery life.
On top of that, you can choose which of the RFLKT's four buttons perform certain functions, such as changing the music track and switching between displays on the device. Other functions the app offers include monitoring lap times, and starting and stopping the timer. Overall, the amount of customization allowed within the RFLKT's iPhone app is remarkable. Even so, while it has great potential to provide you with a wealth of information, it relies pretty heavily on additional peripherals for a lot of the data collection.
Wahoo Fitness RFLKT Computer: Protect your iPhone
The RFLKT's biggest plus comes from what it doesn't do--namely, it doesn't make you pull out your iPhone when you should be focused on cycling. It lets you keep that expensive piece of technology safely tucked away in a pocket or backpack while you're on the move, keeping your attention on the road. And although an iPhone has no place in wet weather or muddy conditions, the RFLKT is IPX7-certified weatherproof and shockproof, according to Wahoo Fitness.
Another bonus: Since the RFLKT uses low-powered Bluetooth 4.0 to transfer data, you won't have to worry about the device sucking too much juice from your iPhone. After about 2 hours of riding, my iPhone had lost about 15 percent of its battery life. Those cyclists who favor long-distance rides need not worry about completely draining their phone's power.
On the other hand, because the RFLKT runs on a coin cell battery, you will inevitably need to buy a replacement battery when the existing one runs low. Wahoo says the included coin cell battery should last a year. More fitness tech: Nike+ Fuelband vs Fitbit One comparison review.