I installed a CatEye 410DW on my wife's bike last year and it came with this sensor. I followed the instructions for mounting the magnet to the crank arm (rear mount sensor) but it keeps sliding. The tape does not hold up in the heat. Any hot tips for keeping the magnet in place? I thought about using some JB Weld to adhere it to the crank arm. Any tips or tricks would be appreciated!

Thanks!