Review on CYCPLUS Bike Computer Set: Speed Sensor, Mount, and Wireless Odometer - Waterproof ANT+ Bluetooth MTB Tracker by Jamar Gow

With its GPS capabilities, you can not only get speed data, but also topographical data such as elevation, gradient, and incline. In addition, you can sync and play your travel data with your iPhone. It will also be connected to a heart rate monitor and a power meter. You don't need a speed sensor, but the magnet can be used as a cadence sensor. I'm really glad I bought Cyplus. Update: Cycplus warranty support is excellent - I had an issue with my Cycplus M1 bike computer and they sent me a replacement with no hassle.