I'm a cyclist. I'm not a 6 A.M. 30 miles before work cyclist. In a scale of intensity, I'm somewhere in the middle. If I lived near my parents, brother, and friends who are more avid cyclists, I'm pretty sure I'd bump up a few points on the serious cyclist level.
NEED
I wanted a way to track my speed and cadence. So I bought the Wahoo Fitness Speed and Cadence Sensor. The app appeared to be much more precise than just using Strava (although I haven't done serious testing to determine whether this is the case. Also, I use the Wahoo app which allows direct upload to Strava, which I use). The problem I quickly faced was how to see the quick glance information I needed: Current speed, average speed, time, and trip distance. My iPhone was in my jersey pocket and only accessible when I stopped. So I started looking for a mounting solution for my handlebars.
MOUNTING
It didn't take long to realize that the Quad Lock Bike Kit looked like the best option out there. I got my hands on the Quad Lock Bike Kit. Installation, if you can even call it that, took about 30 seconds. The mount uses two black elastics to mount onto the handlebar stem. Then I slipped the case onto my iPhone 5. Let me talk briefly about cases. I'm not a case guy. During my time the past 6 years of having an iPhone I have tried different cases, but typically prefer to go nude. So I was skeptical of having to use my phone with the Quad Lock case. However, it is a nice soft material and quite thin, despite the fact that it has the locking area indented on the back. I really don't mind the case and it is one of the reasons I still really love the Quad Lock system.
USE
The Quad Lock has been fantastic. It holds my iPhone completely stable and has never once given me reason to fear of it falling off, even when I've hit some nasty Chicago potholes. It is super quick to twist on or off, which is nice when you need to quickly pull over to answer a call. I really like the angle that the mount holds my phone, making it very easy to quickly glance at my screen for the information I need.
RECOMMENDATION
There are a number of different options for cycling computers. You can snag a really affordable one ($20 on Amazon) and it will tell you basic information but lacks the ability to sync your information with a service like Strava. You can get a Garmin, but they can get expensive quick. Or you can use your iPhone, which is what I have opted to do. The only real downside is battery drain, but I've found either dimming the screen or turning off the screen (when knowing your speed and cadence isn't essential) will greatly improve battery life. The Quad Lock is also available for the iPhone 5c, 4/4S, GS4, and the GS5. They also make a mount that uses 3M adhesive to mount directly to a different phone or case. I've loved mine and am looking to get a second Quad Lock mount for my commuter bike as well as the car mount for navigation in the car (since my Garmin was stolen last year).