Wait, 75 hours = 2 years of use?
In the winter I ride both to work and back every day in the dark. That's about 110 minutes a day, or 36 hours a month. 75 hours would be < 2 months in the winter for me.
Also, that bike light is ridiculously weak. it's not even bright enough to count as a "be seen" light IMO. On my every day ride I'm hitting 30+ MPH at several points and averaging about 19 to 20 MPH, sometimes the 30+ MPH sections are on bad road where I need to see in pitch black darkness 40 to 50 feet in front of me or I risk hitting bad holes and getting pinch flats. That light looks about as powerful as the screen on my phone - I'd probably get more usable light putting my taillight on the front of my bike.
It's no wonder riders there go 5 MPH everywhere if that's their idea of proper lighting.
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Work: the 8 hours that separates bike rides.