As mentioned already, ridewithgps and strava and good options even in their free versions. No problem with data usage and you can set them so they'll wait until you have wifi available before uploading your ride data to the internet. Of course they will need the GPS circuits in your phone to be active so there is some impact on battery life. Depending on how long your rides are you may want to add an external battery (I have one that doubles as a phone case). You can also save on battery power by switching the phone to 'airplane' mode while riding.