billridesbikes

An accurate way would be to use Goggle maps distance measurement tool and trace your route using the breadcrumb method to find the distance of the route. The bike computer will probably measure something slightly longer due to errors in elevation. Elevation in Goggle maps won't be as accurate as surveyor data so the longer the distance the larger the error, but you wouldn't be wasting your life walking around with a surveyor wheel all day either. In addition if your state board is very zealous there is a small chance you could get fined for 'practicing land surveying without a professional license'. As we engineers like to say, don't let 'the best' be the enemy of 'the good'.

https://support.google.com/maps/answ...form%3DDesktop

njkayaker

The google distance will likely be shorter than the actual distance traveled by the bike (the bike isn't going as straight).

billridesbikes

Correct. And I think Goggle Earth assumes a perfect spherical Earth, so there will be some error for that as well. For example if you take 1 degree arcs around the equator on Goggle Earth and compare them to published values they're slightly off. A 1 degree arc at the equator should be 111.3195km but Goggle Earth will measure 111.1951km or about a .1% error.

prj71

When a speed sensor is paired with a Garmin Edge bike computer it it will automatically calibrate after riding for 1 mile.