B’Twin’s wireless Count 14+ is packed full of features such as a cadence sensor and the ability to set targets for parameters including speed and cadence. It uses the ANT+ protocol, so can also work with a heart rate monitor.
It is a little fiddly to set-up, as the wheel speed and cadence sensors have to be positioned just-so. Once working, it’s easy to operate and the simple display provides lots of useful information.
It is prone to stopping working if the sensors (mounted on the chainstay) move, but that’s simple to fix. You can also use B’Twin’s software to download your rides to a computer for analysis.