The rear light attaches to a mounting plate. The plate can be velcroed horizontally or vertically.
Velcro is 3/4" wide and 12 and 3/4" long. The light will still mount in the same position.
The rear light aspect in relation to the ground is not a problem on my Bell Metro.
I don't think there will be a problem on your helmet. If so I would use some material between my
helmet and the plate to change the angle. Just a test ride around my neighborhood so far.
Both lights are bright. The 3 leds on the rear light do a steady blink. No rear button to change
the display.