zacster

I just picked up a Garmin FR 110 on ebay and used it for the first time today. It did prove that my old Cateye Astrale 8 wired computer is dead on accurate for distance. They both said 19.37 miles at the end of my ride!

prathmann

Nice that they agree, but I'd draw the opposite conclusion - you showed that the Garmin GPS is accurate. In case of disagreement I'd trust the unit that just has to count wheel revolutions and multiply by the user-measured circumference as opposed to the device that has to listen to weak satellite signals from 12000 miles away and requires synchronized time sources accurate to the nanosecond level.

zacster

That would be a bad assumption. I've never measured the circumference of the wheel and use the pre-programmed circumference instead. GPS is generally accurate within about 3 feet ( or is it 3 yards?) at any point of your ride. In the car it even knows which lane you're in. I'd vote for GPS always being right before my wheel magnet.

In any case, the HRM is pretty cool to have. I was doing loops of Prospect Park and know every up, down, bump, curve, sewer, depression, even the lane markings, and I know what my effort will feel like at every spot. It will be good to translate that so I can consistently see it when I'm not in the park. I'm not sure though that I always want to know.

ItsJustMe

You've proven that they're both the same. It doesn't really prove accuracy. It proves precision.

That said, the GPS is proven accurate by other means. But having two devices that happen to agree doesn't mean that they're right.

TrojanHorse

Wait till you get a GPS track that takes you out into the middle of the pacific ocean in the middle of a ride and you might re-think your GPS is always accurate assumption.

Generally speaking, they're "good enough" not perfect, and that's fine for what cyclists use GPS for.