Joined: Dec 2004
Posts: 12,548
Likes: 797
From: Middle of da Mitten
Bikes: Trek 7500, RANS V-Rex, Optima Baron, Velokraft NoCom, M-5 Carbon Highracer, Catrike Speed
if you're measuring a 20% grade and you incorrectly use the distance traveled instead of the horizontal distance, you'll be off by 0.4%. For lesser grades, the inaccuracy is less. My conclusion: it's not exact, but it's close enough fer gov'mint work.