Originally Posted by
Slaninar
Drivers approaching from the rear will see you directly in front of them. Additional visibility benefit of a light (in daytime) for such scenario is very small. Speed difference is much smaller - your speed is deducted from their speed.
I think it's better to be seen than not to be seen. Speed difference is highly dependent on the particular road in question. Anecdotally, bikes with no rear lights are easy to miss unless the rider is wearing high visibility clothing. It's not just getting hit from behind that's a problem but getting right hooked from cars approaching from behind. If the light is bright enough (and the Dinotte in strobe mode is VERY visible) you can be picked up for over 1/2 mile away even in broad daylight.