do you guys have any mobile phone app or do you use any special gps device to measure VMG?
any recomendations on both?
I am not sure but I think the GPS phone apps are a little suspect and give out some bad data like you are going 35 knots when really you are hitting around 24.
The GT 31 by Locosys is the standard and you can get different programs to read VMG. I saw Joey Pasquali and Simone Vanucci with some very high tech GPS watches that I think cost around $500 each but not sure what brand they were. They would plug in the data together on the computer and watch themselves race each other, pretty cool stuff..