I asked the same question a few weeks ago and was pointed to the view ranger app,
I down loaded the app, bought the 1:25K maps of the lakes and a holder for the bike, Using an iPhone 4.
This allowed me to load in routes for me to follow when in areas I’m unfamiliar with and opened up a whole new world for me.
All great stuff, BUT using an iPhone 4 on a ride over 4 hours the battery was ready to die and with no means od changing the battery i was snookered.
Bit the bullet and bought a Garmin 800 trail bundle i the end. must say though i found view ranger better to use.