All of Colombia is awesome. Old Cartagena very cool. Check out Motolombia Bike Tours for routes. Medellin certainly worth a visit. Best of luck. Ill be hanging out in San Deigo the next few months. Cheers

Northbound vs southbound
 

Hola Andy,
I've riden from Canada to Colombia over past five months and I'm now enjoying friendly Medellin. Stop in for a drink and we can swap travel info and stories. Cheers!
Steve