GPS not so good for mountain biking – Runtastic Road Bike GPS Review

I’ve been using this for a few months now. I ride on trails in remote places. I use the app on an iPhone 6. It was killing my battery within a half hour, but I replaced the battery and that has fixed that problem for now. I rode today, my cyclometer said I had gone 11.6 miles, but the app only recorded 10.3. I know the cyclometer is correct as it’s set to the circumference of my wheel. Other than that, so far everything seems fine.
Review by I've been using this for years on Runtastic Road Bike GPS.