Whether I'm on the trails on riding my bike to work, I use Map My Ride to track of my miles, speed, etc.

While it's not perfect, it's simple. I start the app on my iPhone 5, stick it in my bag, and start pedaling. While bike computers are cheaper and simpler to use than ever, I like that I can keep all my data in an app, just a tap away.

The Wahoo Fitness Blue Cycling Speed & Cadence Sensor is the best of both worlds, however. The battery-powered device connects to your iPhone (to Wahoo's own apps and others, including Map My Ride) via Bluetooth.

The device clips to rear chain stay and uses spoke and crank magnets to track bike speed and pedal rotations per minute.

Check it out on Amazon.