Now you can train and measure your time on pumptrack alone!

Application allows you to measure laps with your iPhone.

Place your phone perpendicular to the pumptrack trail and point camera around 2-3 meters away. 
Make sure you'll cross camera image with your front tire not more than 80 cm from the phone (Less is better). 
Place your phone on the ground, hit \"Activate\" and try not to move your phone. 
Go ride and app will automatically measure laps for you!