Hey Philip, that magnet is about 6mm across and maybe 4mm long... it's tiny. Yeah, it wouldn't take much for the magnet to be too long and hit the chain adjuster... I'd say I have about 1 mm of clearance. I had to crazy glue it on the sprocket bolt so it wouldn't jump onto the adjuster. As far as the sensor goes, it's about 9mm away from the magnet and works just fine. This magnet is one of those rare earth magnets so it really strong.
The Acewell lights suck on my model. They are dim and the light they produce tends to bleed off to adjacent lights so they end up interfering with each other. I'd keep the console lights if I were you... even change them over to LED.
