Every now and then, Runtastic throws a bone to active and sporty people by discounting its Pro apps to zero. That's zilch. No pennies, no dimes, no dollars. It's happened with Sit Ups Pro, Pedometer Pro, Road Bike Pro, and now is the time for Mountain Bike Pro.

For mountain bikers, Runtastic's app provides MTB tour tracking and thousands of bike routes, voice coaching so you don't have to get your eyes off the road and risk an injury, live tracking, offline maps for those out-of-reach areas, music controls, and plenty of stats and graphs to satisfy your inner nerd or your thirst for improvement. All of that comes without ads or IAPs.

Some of the latest reviews complain of freezes and issues with modern phones, but the Runtastic team seems on top of them. Besides, at the nice price of free instead of the usual $4.99, you won't be losing much if you grab it and give it a go. Just make sure you do so soon, as the price drop is temporary.