Originally Posted by
Iride01
If you only got 400 feet of notice then something was wrong. I notice of vehicles very far away and Garmin's claim of 153 yards (140 meters) seems pretty accurate and even conservative.
Product page has the dreaded "up to" qualifier on that 153yd/140m specification - so 400ft instead of 459ft (153yd) isn't that far out of line -- and it's possible Ghostride62 was approximating the distance as well.
Is that enough? I'd say it depends on one's situation. With a closing speed of 60mph - such as riding 10mph with traffic going past you at 70mph, you'd get 4.5 to 5 seconds warning. With a 30mph closing speed the time is 9-10 seconds.
All I know is on the roads I ride, my Varia tells me about cars before they're easily seen in my mirror, and I can easily hear the alert tone on my 830. Maybe the system isn't perfect, but I'm better aware of cars than when I was just using a mirror.