Bought this along with the HRM which sadly failed after 3 months, but the SC is still going strong fingers crossed. Fitting the unit to my MTB was very easy and only took 20 mins which included removing the peddle. In terms of design the main unit is great although can be easily knocked out of alinement but if you do a quick visual check before setting off then all should be good. The minor issue I fell is the magnet that you fit to the spoke of the back wheel. This doesn't tighten on very well and is prone to spinning round or sliding along the spoke. I have added some tape to prevent the sliding but it still tends to swivel round the spoke. I would have preferred a better method of fixing maybe across 2 spokes for a more accurate placement. That said I haven't had issues with the sensor not picking up the revolutions of the back wheel even with some quite extreme terrain. I will be looking to fit a different magnet soon.