I run Strava with my iPhone. I like Strava because I have my different bikes saved on there, and have various parts listed on my bikes, with dates installed, so it shows me exactly how many miles are on various parts.

For instance I installed my road bike's current tires exactly 13 months ago today, and have 3,165 miles on them. Rear tire is showing some wear, so I'm hoping I make it to 5K miles on them.