Originally Posted by Seattle Forrest

Try your phone. You already have it. Lots of people use them and are happy, you might be one. If not, you'll make a better choice when you buy a dedicated bike computer because you'll have had some experience using one and you'll know what's most important to you.

Google My Tracks is limited but free, and if you use it with one of the free workout tracking sites will get you some basic info like a map, speed (after the fact) and so on. People also like bike-specific apps like Strava, Ride with GPS, Map my Ride, and many others.