runtastic has Mountain Bike PRO Cycling Computer (iTunes Link) for the iPhone and iPod Touch in the iTunes App Store for FREE (regularly $5.99) for a limited time.

Turn your iPhone into the perfect bike computer with plenty of features. Whether your track is a lap around your house or it is in the deepest mountain trails, the runtastic Mountain bike app is your ideal companion.

Mountain biking is the perfect mix of exercise, fresh air and beautiful nature. Drive where the road leads you without losing orientation. The offline-maps function gives you the possibility to use the maps even without GSM coverage so that you can be with the nature and with your bike at the most remote trails. It makes no difference whether you are a beginner or you are training for the Olympic Games, the app gives you everything that you as a mountain biker could have ever wished.