I,ve used my Garmin Nuvi 765T for 3 years now on my bike and cars and it works great.
You can make your own routes and upload them directly into your Garmin using this ride planner.
Harley-Davidson - Ride Planner
It was so easy to do .
You just need to register on the HD site and start creating your own routes or you can upload routes others have made into your GPS.
Try it and if you have any questions ask.
P.S. to Bobby K, If you get a GPS get a Garmin, I think you cannot upload routes into TomToms or Magellan units.
Also what ever Garmin you get make sure that if you click on "tools"
that you get a "data" icon ,if you don't have that then you can not upload routes from your computer and you will need to get a Garmin model that has this "data" icon.
Mac