Link to Instalation Installing these sensors can be difficult. They come will with 2 cable's and 2 magnets
Depending on what brakes that you have some are an easy instalation and some are near on impossible to install.
To position the sensor we recommend that you use a cable tie and the double sided tape to hold it in position when testing.
Only then do we recommend using using epoxy.
Below is a post on electric bike forum which show different models