This app was mentioned in 1 comment, with an average of 1.00 upvote
I use a Cateye Enduro, and I usually also track my ride with the Runtastic Mountain Bike app. You do see a slight difference in distances, the GPS usually reports a shorter distance than the bike computer. I've been very satisfied with the Cateye computer, I've had it for a few years. If all you want is to track distance, it's all you need, and it's pretty inexpensive. It is wired, but it uses heavier duty wires that should hold up better to abuse on the trails.